OSP Fiber Optics

Civil Works Guide

An updated version of this booklet is now available as a

textbook on Amazon, is included in the FOA Reference
Guide to Outside Plant Fiber Optics and as a section in the
FOA Guide website.
©2015 Joe Botha and The Fiber Optic Association, Inc.

Like all standards, this document only offers guidelines for design, installation and testing of fiber
optic networks. The owner, contractor, designer or installer is always responsible for the work
involved. Mr. Botha and FOA assume no responsibility or liability for the use of these standards
nor for any projects using them.

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 Contents
Introduction to Optical Fibre 2 Cable play-off 22
Why Fibre? 2 Air-Assisted Installation Practices 24
Fibre Geometric Parameters 3 Jetting and blowing 24
Core, Cladding and Buffer coating 3 Air-Assisted Practices 25
Cable Jackets 3 DIT 25
Strength members 3 Micro Duct Fill Ratio 26
Moisture/Water-blocking 3 Cable Blowing Lubricants 26
Micro Technology 4 Cable Bend Radius 27
Micro ducts 4 Figure-eighting 27
Micro cables 4 Micro Duct Tools and Accessories 28
Colour Coding 4 Aerial Works 29
Environmental 5 Pole Handling PPE 29
EMP and ECO 5 Transportation of Poles 29
Responsibilities 5 Pole Off-Loading Procedure 29
Water, dust, air, noise, traffic, trees, archaeology 6-7 Pole handling ratios 29
Health and Safety 8-9 Ladders 29
Responsibilities 8 Survey Equipment and Tools 30
Site File Contents 9 Survey - Gather Route Information 30
Wayleave’s 9 Checks to be undertaken 30
Trenching 10-18 Wooden Pole Inspection 31
Pre-build Procedures 10 Hole-digging Tools 31
Trench Depth 11 Pole Holes 31
Sludge Test 11 Poles set in Concrete 32
Trench Width 11 Pole Spacing 32
Pilot Holes 12 Suggested Aerial Work Practices 32
Location of Services 12 Selection of Pole and Stay Positions 33
Trench Shoring 12 Types of Stays 33
Notifications 12 Stay Guards 33
Private Property 13 Struts 33
Suggested Trenching Practices 13 Stay Holes 33
Barricading 13 Stay Spread/Height Ratio 34
Trenching near Paving, Guttering, etc. 14 Termination of Stay Wire 34
Crossings, River, Bridge, Road 14 ADSS Installation 35
Duct Deviation 15 Power Crossings 35
Trenching near Power Cables 15 Cable Clearance 36
Steep Gradient Trenching 15 ADSS Installation Conventional Method 36
Tree Roots 15 ADSS Installation Figure 8 method 36
Surface material 15 Dead-End Sizes 36
Duct Un-Coiling Installation Process 16 ADSS Terminations and Support Types 36
Moving Trailer Method 16 Securing of Cable to Poles 37
Mechanical Machine Pulling Method 16 Dynamometer 37
Bedding and Padding 16 ADSS Sagging 38
Backfill 16 Cable Slack 38
Trench Compacting 17 Damage by veld fire to aerial-cables 38
DCP Test 17 Cable Hauling 39
Direct-Buried Installations 17 Pre- Installation Checks 39
Earthing and Bonding 18 Duct Rodding 39
Markers 18 Duct Testing and Cleaning 39
Manholes and Handholes 18 Centre-Pulls and Back-feeding 39-40
HH / MH Inspection 19 Pulling Tension 40
Safe HH / MH Working Procedures 20 Pulling Grips 40
Directional Boring and Hammerhead Mole 21 Hauling Rope 40
Reinstatements 22 Duct Fill Ratios 41
Pre-installation Cable Testing and Inspections 22

Although the recommended practices and descriptions are all typical techniques used in South Africa - it is
intended for use only as a guide and should under no circumstances be used in place of a prescribed Installation
Specification pertaining to your project. Although reasonable steps have been taken to ensure the accuracy and
completeness of the contents, there will unquestionably be instances where such information proves inaccurate
and/or incomplete.

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Introduction to Optical Fibre
Why Fibre?
Since the introduction of fibre in the 1970s, optical fibres have revolutionised communications, transmitting
more information over greater distances than could ever be achieved in copper wires.
We live on the continent (Africa) that gave birth to the concept of the ‘Digital Divide’. But this being said,
fast forward a few years, and today, the uncompromising amount of bandwidth we demand from Internet
services is nearly insatiable. Why do we need all that bandwidth? The past 10 years have seen a
tremendous increase in Internet bandwidth requirements, driven by high-capacity business data services,
increasingly powerful 3G/4G wireless smartphones and video-intensive websites such as YouTube, Netflix,
etc.
Buoyed by the surge in demand for digital data, local telecommunication companies are looking to reinvent
themselves to support the need for faster data rates and smarter network architectures, potentially
hamstrunged by the predicament of having to handle unpredictable and fast-changing traffic patterns.
Optical fibre technology provides a higher capacity data transfer at extremely high speeds, enabling the
facilitation of video content on networks. In this context, community or service providers can now supply a
wide range of services and applications, such as High Definition TV (HDTV), Video on Demand (VoD) and
high-speed data and on top of this, provide for the basic fundamentals of voice connectivity. Who would
have dreamed that operator’s largest revenue component voice, might in the not-too-distant future, be
surpassed by data and content provision services?
Switching a laser beam on and off at high speeds is how we communicate now over fibre. The laser light
flashes on and off in a sequence that represents the information being sent. The quicker the lasers can
flash on and off, the quicker the information can be transferred. The speed of transfer is known as “bit-rate”
and is usually talked about in terms of bits per second - bps or bit/s (which effectively is the number of
flashes possible per second). Modern networks typically transmit at a minimum of 10 Gigabits per second
from a single laser, which amounts to 10 billion flashes per second.
And goodness me, Alcatel-Lucent recently (Jul 16, 2013) transmitted as much as 31 Terabits per second
over 7200 km on a single fibre i.e. 155 x 200-Gbps channels. The fibre link featured amplifiers every 100
km and as far as I know, the highest sub-sea capacity ever transmitted on a single optical fibre.

Fibre Advantages - a brief summary

- It has exceptional bandwidth
- It has the ability to carry many signals concurrently
- It is immune to electromagnetic interference
- It has no electromagnetic emissions
- It does not corrode like copper based cabling does
- It is resistant to eavesdropping
- It is virtually "future proof"
- It has the capability to operate in conjunction with any current, or proposed, LAN/WAN standard
- It is light weight and easy to handle
- It’s pulling strength is much higher than that of copper cables
- …and on it goes

Skilled Labour
Some service providers may have their own labour while others rely exclusively on contractors. The trouble
is that skilled labour is not always readily available. Because performance is so clearly measurable and
apparent, FOA trained labour remains an important requirement, particularly for guaranteeing that a good

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end product is delivered. Even with the much more resilient and robust bend-insensitive varieties, optical
fibre is still glass and requires both skills and knowledge to install.

Fibre Geometric Parameters

Fibre can either be single-mode (SM) or multimode (MM). Fibre sizes are expressed by using two numbers
e.g. 9/125. The first number refers to the core size in microns and the second number refers to the core
and cladding size combined in microns. It is impossible to differentiate between SM and MM fibre with the
naked eye. There is no difference in the outward appearances; both are 125 microns in size - only the core
size differs.

The construction:
Core: The optical core is the light-carrying element at the centre and is
usually made up of a combination of silica and germanium.
Cladding: Cannot be removed! The cladding surrounding the core is
made of pure silica and has a slightly lower index of refraction (i.e. less
dense) than the core. This lower refractive index causes the light in the
core to reflect when encountering the cladding and remain trapped within
the core.
Buffer coating: This is removed during stripping for splicing or
connectorization and acts as a shock absorber to protect the core and
cladding from damage.
Cable Jackets
Polyethylene (PE) is the material of choice for use as
an Outside Plant (OSP) cable jacket. The performance
of raw PE can degrade rapidly through exposure to
Sunlight. For this purpose, Carbon Black is combined
with the PE and is used to absorb the UV light and
subsequently dissipates. Jacket colours other than
black are used for reasons of enhancing identification.
Cable jackets shall be marked with manufacturer’s name, month and year of manufacture, sequential meter
markings, fibre type, the number of fibres, along with a telecommunications handset symbol. Cables
without these markings will not pass inspections and should not be installed.
Strength members
Aramid fibres (Kevlar - a very strong, very light, synthetic
compound developed by DuPont) – is used when a
cable is pulled into a duct, with the tension being applied
to the Kevlar. The Kevlar is used as a draw string to pull
the cable into the duct so as not to put stress on the
fibres.

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The term is also used for the fiberglass or steel rod in some cables used to stiffen it. Impact resistance,
flexing and bending are other mechanical factors affecting the choice of strength members.
Moisture / Water-blocking
In a loose tube cable design, a filling compound, water swell-able yarns or gel
(a soft, gooey, substance) are commonly incorporated in the cable. This
minimizes the chance of water or moisture penetrating the length of the tube in
the event that the tube is damaged. When water freezes it expands by
approximately 9% - therefore, water in a cable can cause repeated freeze and
thaw cycles.
Micro Technology
Since SM fibre was first introduced in the early 1980s, not too much has changed in its basic geometric
parameters. The SM core size has remained somewhere between 8 and 10 μm - the core / cladding
diameter has remained at 125 μm. The outside plant (OSP) coating is now either 200 or 250 μm. Most
notably, standardising these dimensions has greatly improved interoperability and consistency across
optical networks.
A new-ish component to the system is microducts made of high-density polyethylene (HDPE) material.
They are typically installed as bundles in larger ducts. It’s generally accepted, that deploying microducts is
an economically sensible option, helping to avoid the costs of subsequent civil works.
Microcables offers a great deal more density. Only a few years ago, a cable diameter of ± 12 mm was
required for a 48-fiber cable design. Today, cables with 8 mm diameter cable has a capacity of 144-fibres.
This is achieved by using 200μm coated fibres. The 200 μm coated fibre’s cross sectional area is ± 46%
smaller than that of the conventional 250 μm coated fibre.
Micro cables are designed for jetting, with high-density polyethylene (HDPE) outer sheaths in order to
minimize friction with the inner surface of micro ducts. Perhaps more significantly, these cables also have
optimal stiffness properties to help prevent buckling and easily negotiate modest changes in direction of the
micro duct along the jetting route.
The central tube micro cable design also provides the highest fibre density, yielding a relatively small cable
OD. The individual fibres are bundled into groups of twelve within the cable’s central tube, and the bundles
are easily identifiable with coloured binders in accordance with EIA/TIA-598B, "Optical Fibre Cable Colour
Coding”.
EIA/TIA-598B, "Optical Fiber Cable Colour Coding”

NB, colour codes differ from supplier-to-supplier.

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Environmental Considerations
It is the Contractor’s responsibility to prepare a site-specific Environmental Management Plan (EMP) and
submit it for approval. Each site is unique and therefore the environmental issues to be considered, will
vary from site to site.
Environmental Control Officer (ECO)
1 A good place to start with, is the appointment of an Environmental Control Officer (ECO), to manage
and oversee the environmental aspects of a project.
2 Mindful perhaps of Henry IV’s favourite whinge “uneasy lies the head that wears the crown”, the
ECO shall:
- Prior to work commencing, unravel the requirements of the EMP to the appointed Contractor
to ensure understanding and conformity
- Visit the site weekly
- Review and approve all areas that have been rehabilitated by the Contractor
- Keep a record of findings
- Attend all project meetings
- Produce a monthly report, with commentary on compliance and/or non-compliance
- Keep an Incident Log of non-compliance
- Maintain a record of complaints from the public and communicate this to the Contractor
- Where necessary, issue a non-compliance report to the Contractor
- Where serious environmental infringements have occurred, introduce a Temporary Work
Stoppage
- Liaise with the appointed Occupational Health and Safety Officer

An Environmental Management Plan (EMP) must include:

A brief summary of what an EMP might contain, but is not limited to:
1. Statement of Commitment
2. List of activity-specific environmental issues related to your site and their likely impact
3. Incorporating the above, write a series of simple work instructions to ensure compliance
4. Determine the actions required to manage each work instruction
5. A list of tangible contingency and mitigating actions to be implement if required
6. Provide training to staff and create awareness
7. Monitoring and Reporting
8. An organisational chart setting out respective roles and responsibilities

Contractor Responsibilities:
1 Be familiar with and comply with the procedures contained in the EMP.
2 Ensure that all personnel are qualified and experienced enough, to undertake their work in an
environmentally responsible manner.
3 Create an awareness of the Environmental work instructions and the need for them amongst the
workforce.
4 Procedural briefings to be given before personnel carry out key activities for the first time.
5 Ensure that personnel who have formal responsibilities under this plan, are trained in the
requirements of this EMP.
6 Ensure that the necessary permits have been obtained before commencing with work activities.
7 Undertake daily site inspections to monitor environmental performance and compliance.
8 Immediately notify the ECO in the event of infringements.
9 Notify the ECO and in advance of any activity he has reason to believe that may potentially have an
adverse environmental impact.

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10 It is desirable for Environmental matters to be included as a standard agenda item at all project
meetings.

A few Activity-specific Guideline Examples:

In what follows, are a few activity based examples an EMP might contain, but is not limited to:

Water
1 Storm water must be contained in the storm water system to avert flooding.
2 Measures must be implemented to distribute storm water as evenly as possible to fend-off soil
erosion.
3 Material from any stockpile must not be allowed to fall or be washed into a drain.
4 The execution of any work shall not block and subsequently unsettle the existing overland water flow
or the existing system of drains.
5 No person may, without prior written permission release water onto a public road.
6 No person may, without prior written permission raise the water level of a river, stream or dam which
can spill-over onto a public road.
7 No work shall be carried out within 32m of any natural water source without permission from the
ECO.

Dust / Air Pollution

1 Where necessary, issue workers with washable dust masks for protection against dust inhalation.
2 Dust must be controlled onsite, especially when windy.
3 Minimize or even cease activity during periods of high wind.
4 Dampen surfaces to prevent dust from becoming airborne.
5 Cover materials being transported with plastic sheeting or a tarpaulin to prevent them from flying off
the vehicle. Dampening of the transported material may also be necessary.
6 Cover onsite stockpiles with plastic sheeting or tarpaulins during high wind.
7 Regular maintenance of generators, compressors, etc., is essential for controlling exhaust
emissions.

Noise Pollution
1 Contractors must abide by the National Noise laws.
2 Develop a noise mitigation plan before starting with construction.
3 The level of noise and the duration thereof must be agreed upon and monitored.
4 Examples: Jack hammers, concrete saws, bulldozers, trucks, generators,
compressors, pneumatic tools, power tools, etc.
5 When talking to someone 1m away and you have to shout to make yourself heard,
then noise levels are definitely too high.
6 Hand-held sound meters are lightweight, easy to operate and relatively
inexpensive.
7 Hearing protection will be worn at all times when noise levels are suspected of
equalling or exceeding 85 dBA.
8 Noise PPE:
- Use disposable earplugs only once
- Keep reusable earplugs clean
- Earmuffs must be a good fit
9 Where possible, restrict construction work to weekdays and limit work hours from
08h00 to 17h00.
10 Should an extension of the work hours be required, the adjacent property owners shall be informed
in writing 2-days in advance of any proposed overtime activities.
11 Whenever practical, noise levels identified as exceeding 85 dBA, Noise MUST be reduced by using
mufflers, barriers, etc. or the following actions must be implemented once the source of the noise
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 has been ascertained:
- Replacement or adjustment of the worn or loose parts
- Balancing the unbalanced equipment
- Lubrication of the moving parts
- Use of properly shaped and sharpened cutting tools

Traffic
1 No work should commence on a public roadway without first obtaining a work permit from the road
authority concerned.
2 It is the responsibility of the supervisor/s to ensure that each member of his crew wears the required
PPE and to ensure that the work area is protected by the use of the various signs, cones, flashing
lights, traffic control personnel, etc.
3 Traffic movement should be inhibited as little as possible. Should this be unavoidable, alternative
access to routes must be made available.
4 Roads shall be kept free of debris or equipment.
5 Excavated material unsuitable for re-use shall be removed from site as soon as possible.
6 Where cyclists and/or pedestrians are likely to be present, their need for safe and convenient
passage must be considered and sufficient, safe crossings shall be planned for.
7 Create ‘no go’ zones around hazardous areas and implement safe work distances.
8 Choose signs with messages clearly indicating the actions drivers or pedestrians are required to
take.
9 Where necessary, traffic control persons must be used to provide positive guidance to motorists.
10 Remember that the visibility of hazards/workers can be greatly diminished in darkness and/or poor
weather conditions.

Trees
1 Trees must not be cut or trimmed unless consent is obtained in writing from the owner or the relevant
authority.
2 Cutting must be confined to what is absolutely necessary.
3 Tree roots exposed in the way of the trenching must not be cut unless absolutely unavoidable.

Archaeology and Cultural Heritage

1 Even with no designated sites of archaeological sensitivity being identified along a route, the
Contractor will be required to have measures in place to deal with potential finds protected by the
Natural Heritage Resources Act, Act 25 of 1999.
2 Construction in the vicinity of a finding, must be stopped and under no circumstance may any
artefacts be disturbed or removed from the site.
3 An archaeologist can be called to the site for inspection and the South African Heritage Agency
must be advised.

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General Health and Safety Guidelines
There is little doubt that an approach that minimizes or even better, eliminates possible accidents or
incidents is highly advantageous.
Responsibility of Management: It is the responsibility of management to ensure that all team members
and supervisors are trained and familiar with applicable safe working practices, and that they take
immediate and decisive action when safe and approved work methods are not followed.
Responsibility of Supervisors: It is the responsibility of the supervisors to ensure that each member of
his team wears the required PPE and to ensure that the work area is protected by the use of the
necessary signs, cones, flashing lights, traffic control personnel, etc. Personal protective equipment
(PPE) refers to protective clothing, hard hats, safety glasses, or other garments or equipment designed
to protect the wearer's body from injury. On top of this, practice safe and approved work methods, as
generally outlined in this Manual.
Each Party must at all times comply with health and the safety legislation, regulations and guidelines,
which must include, but is not limited to:
1 A competent person shall, before the commencement of any construction work, perform a risk
assessment which shall be written into the health and safety plan to mitigate risks and shall include:
a. Activity-specific hazard and risk identification.
b. Assess and evaluate each identified hazard and risk and rank them i.e. high, medium or low.
c. The best way to protect people is to eliminate the hazard or risk and second best, minimize
it.
2 All areas used by the public shall be maintained free from debris or equipment that may constitute
slipping, tripping, or any other hazard.
3 Adhere to all the health and safety management plan procedures.
4 Develop and obtain approval for a Traffic Management Plan (TMP).
5 Report and record all Work Site accidents, incidents and property damaged.
6 Establishing safe air space requirements prior to the use of lifting and construction equipment.
7 All personnel shall be required to wear the following personal protective equipment (PPE):
- Protective overall (at all times).
- As a general rule, steel-toed safety boots should be worn at all times.
- Hard hat (when performing work that requires the use thereof).
- Safety glasses (when performing work that requires the use thereof).
- Work gloves help prevent cuts and bruises from sharp or rough edges on pipe/ducts and
other objects.
- Wear high-visibility vests when working at or near a public street or highway or when working
at night.
8 The contractor shall ensure that all necessary guards, protective structures and warning signs are
used to protect both workers and third parties. All necessary barriers and fences shall be erected to
guide pedestrians and traffic around the work area.
9 A first aid box will be provided and allocated to a trained, certified first aider. Every injury occurring
on site must be treated and recorded.
- Should an injury require professional medical treatment, the supervisor in charge must
complete an accident report.

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 - Ensure that the first aid kit is available and accessible, correctly stocked and a register exists
to account for used/missing items.
10 All employees, management personnel and visitors shall undergo induction training carried out by
the Site Manager or a designated deputy before going onto site for the first time. Inductions records
shall be kept on site for the duration of the project.

Typical Table of Contents for a Site Safety File

1. Notification of Construction Work 15. Certificates of Competency
2. Letter of Good Standing 16. Risk Assessments
3. Organogram 17. Induction Records
4. Health & Safety Policy 18. Toolbox Talks
5. Health & Safety Plan 19. Inspection Registers
6. Environmental Policy 20. Visitors Register
7. Environmental Plan 21. Complaints Register
8. Waste Management Plan 22. Site Diary
9. Fall Protection Plan 23. Weekly Statistics
10. Emergency Plan 24. Safety Minutes
11. Emergency Contact Numbers 25. Audit Template
12. List of Sub Contractors 26. Vehicle List
13. 37.2 & 5.3.b Legal Agreement 27. Incident Records
14. Appointments 28. Client’s SHE Specification

Wayleave’s (Rights of Way or Easements)

“Never assume anything!” I am somewhat skeptical (some may say: paranoid) about the accuracy of the
information presented in a Wayleave. There is little doubt that a pre-build survey set to verify the exact
location services indicated (or not) in Wayleave’s, will do no harm.
A Wayleave is permission to use someone else’s property to deploy infrastructure. In other countries this is
also known as a right-of-way or an easement.
A Wayleave agreement must be obtained prior to installing any telecommunications equipment.
Companies doing work in a Road Reserve must at all times keep a copy of the Wayleave on site.
Companies must familiarise themselves with the Standards and special conditions as set out in this permit.
Companies are held responsible and accountable for the quality of work they deliver.

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Trenching
Pre-Build Procedures
1 As an unfaltering believer in a pre-build survey: The verification of details contained in pre-build
drawings, will ensure that potential problem areas are uncovered before trenching kicks-off and
potentially save one a lot of trouble later.
2 Using the information available on the pre-build drawings, walk the pegged out route by foot, to
determine the following:
- Verify the soil classification/s with at least one visual test and one manual test every 1km
- If the soils or soil properties are not what were expected as noted in the contract, the
relevant authority must immediately be consulted
- Check and verify above and below ground utility locations
- Note changes in gradient and/or direction
- Identify all obvious landmarks where the route changes direction (take photos)
- Take photos of all obstacles along the route
- Verify HH / MH positions
- Note road / rail crossings
- Record crossings with other services
- Record the presence of structures near the trench
- Double-check the recorded details on the return journey

Pre-Build Survey Equipment and Tools

1 Digital camera and spare batteries.
2 GPS with tracking function and spare batteries.
3 DCP tester.
4 Tape measure.
5 Measuring wheel.
6 Clip board, note book and stationary.
7 Route drawing/s from the client.
8 Reflector jacket.
9 Personal Identification.

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Armed with this in information, a build plan can be developed and the contractor can ensure that the
necessary equipment and recourses are in place.
Procedures and processes can now also be developed and put into place to ensure that the civil build is
done to standards and executed within budget and timelines.

Trench Depth
It’s immensely important for trenches to be excavated to such a depth
that the crown of the duct has a cover of at least 800mm backfill in all soil
conditions, except for where hard rock conditions are encountered.
Where it is not possible to obtain the specified minimum trench depth, the
relevant authority must be notified.
The trench depth in hard rock conditions can be relaxed to a minimum
depth of 300mm backfill cover over the uppermost duct. But this being
said, it now requires protection in the form of a concrete slab (either pre-
cast, or cast in situ) placed on top of the padding material before
backfilling. Traditionally, this concrete slab must have a strength of 20
Mpa reinforced with high tensile wires and measure; 75mm thick by
300mm wide, and 900mm in length.

Concrete encasing is not endorsed enthusiastically by everyone,

some argue that it turns a once flexible duct into a long
unreinforced concrete beam of negligible strength, prone to
fracture with ground movement. This in turn could potentially
damage an encased duct. A view not shared by everyone.
Before pouring concrete, a slump test must be performed (take
photos of this procedure). How do we measure the ideal slump? Concrete Slump Test
In case of a dry sample, the slump will be in the range of 25- Must not collapse or shear off laterally
50mm and for wet concrete, the slump may vary from 150-
175mm.

Trench Width
One other obvious consideration is the width of the trench, which of course, is dependent on the duct
diameter.
Trenches that are too narrow will not allow for proper duct installation, whereas trenches that are overly wide
are unnecessarily costly. On top of this, a too wide a trench will allow for too much duct snaking from the
reel memory. If no trench width is specified, the typical examples below can be used:

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Pilot Holes
When the trench has been pegged out, Pilot Holes needs to be dug at 30 - 50m intervals, particularly at
points where the new trench crosses existing services. The pilot holes should be at least 150mm deeper
and wider than the proposed trench.
Pilot holes are one of the most effective methods utilized not only for the location of services, but also to
determine the position of a trench, relative to other services.

Location of Services
1 In my view, investing a few shekels in a Ground penetration radar (GPR),
is your ticked to fail-safe trenching. They are used to identify underground
services and formations.
2 No excavation work shall commence without having a copy of the
approved wayleave/s on site.
3 It is the responsibility of the Contractor to locate all existing services.
4 A Utility Representative can be asked to point out the position of a
service and sometimes even oversee the work.
5 Cable Locators can find the exact path and even estimate the depth of the utility service.
6 Hand excavating is necessary to uncover known services prior to commencing with mechanical
excavation.
7 Any trenching done in the vicinity of existing services should be done very carefully to prevent
accidental damage to a service.
8 The Contractor shall be liable for any damages to existing services.
9 Any damage to existing services must be reported immediately to the project manager.

Trenches Deeper than 1.2 meters

1 Where the depth of a trench exceeds 1.2m and workers need to enter the
trench, adequate measures must be taken by the contractor to provide
support for this trench.
2 The 3 basic methods used for protecting workers against trench cave-ins
are:
- sloping
- trench boxes

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 - shoring
… and a ladder provides a safe means of access
3 Barricades and signs are to be used at safe distances from edges to protect
unattended excavations.

4 No person must work alone in an excavation or trench that is greater than 1.2m deep.
5 Machinery must never be placed in or near excavations and trenches where exhaust fumes may
contaminate below ground atmospheres that workers are required to occupy.

Notifications
1 Businesses / property owners shall be informed one week (7-days) in advance of any construction
activities commencing in the vicinity of their properties.
2 Residents whose property may be blocked-off as a result of construction, shall be given warning 7-
days prior to the commencement of any work.
3 If a private driveway and footway constructed with non-standard materials are to be excavated, the
owner of the property concerned must be informed in advance and in writing of the intended work.

Private Property
1 Where possible, excavations on private property shall not be left open outside normal working hours
(08h00 to 17h00). Where unavoidable, the Contractor must take adequate precautions to safeguard
such excavations.
2 The Contractor, on completion of backfilling and compaction, shall restore all surfaces disturbed in the
execution of his work. Surfaces shall be reinstated to the original state or better.
3 Where a Contractor must undertake tree and bush cutting and/or shrub clearing he must prior to
undertaking such work, obtain approval in writing from the relevant authority and/or property owner.
4 The Contractor shall dispose of all cuttings and cleared material.
5 The Contractor shall be solely responsible and accountable to remedy any damages and/or claims,
arising due to his activities.
6 All drainage systems must be cleared daily.
7 In residential areas the reinstatement of paving, grass or landscaping must be done to the property
owner’s satisfaction.
8 Remove all material and equipment not needed onsite, as soon as possible.

Suggested Trenching Practices (possibly not mentioned elsewhere)

1 All excavation work must be performed under the supervision of a responsible person who must be
competent to exercise such supervision.
2 Proper excavation and preparation of the trench will inhibit unanticipated longitudinal and cross-
sectional strains and stresses in the duct.
3 Trench walls shall be vertical for at least the height of the bedding and then as vertical as possible.
4 Exercise care when trimming and/or undercutting trench floors to ensure that only the necessary
amount of ground is removed.
5 The Contractor shall use trenching equipment that is suitable to excavate to the specified width and
depth.
6 A victory for common sense, is to have a ‘good housekeeping’ policy.

Barricading
1 To begin with, provide adequate warning, guidance and protection for
motorists, pedestrians, cyclists and workers from all foreseeable hazards.

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2 In high traffic areas, erect fencing or place barriers measuring at least
1,2m in height – as close as possible to the excavation.
3 An additional precaution is to provide clearly visible boundary indicators at
night or when visibility is poor.
4 Wear high-visibility vests and hard hats when working at or near a public street or highway or when
working at night.
5 When excavations are in progress next to the road, ensure proper and sufficient warning road signs
placed at distances well before and after the work in progress. To warn approaching traffic, a flag man
armed with a red flag must be placed at least 40m before a “men at work” sign. Approved road cones
must be placed at regular intervals along the whole route where trenching is in progress.
6 A flag man is also provided to ensure the safety of team members occupying hazardous positions.
7 Backfill as soon as possible.

Trenching Near Kerbs, Guttering, Paving and Driveway Crossings

1 Where excavations pass beneath kerbs, guttering or driveways, etc.,
proper support shall be provided for these structures until tunnelling
and backfilling is completed.
2 Where tunnelling is not an option, the existing concrete paving shall be
neatly cut with an angle grinder to deliver smooth, uniform edges.
3 Where ducts are to be laid beneath existing paving blocks, the pavers
shall be carefully removed to be reused. Paving blocks must be re-laid
on a bedding of sand and reinstated to its original state or better.

Road Crossings
1 The relevant road authority must be informed 48-hours prior to the commencement of the work.
2 Directional drilling is the preferred method for crossing roads.
3 It is the responsibility of the Contractor to ensure that every law regarding traffic, safety, traffic signs
and barricading is complied with.
4 The angle of the crossing should be as near a right angle to the road centreline as possible.
5 The top of the trench must be cut using asphalt/concrete cutters to deliver smooth, uniform edges.
6 The minimum depth that any service may be placed under a road is 800 mm.
7 The duct/s shall extend a distance of at least 0.5m beyond the edge of the road.
8 All excavated material and equipment must be placed and demarcated in such a way to not
inconvenience vehicles and pedestrians.
9 No person may off-load on a public road, any materials that are likely to cause damage to a road
surface.

Stream and River Crossings

1 When crossing streams or rivers, a 100mm Galvanised Steel Duct is
traditionally used to accommodate sub-ducts.
2 Cement blocks needs be cast at both ends of the 100mm Galvanised Steel
Duct, to secure them and prevent a wash-away.
3 The duct must be sealed at both ends to prevent water or dirt ingress.

Bridge Crossings
14
1 First and foremost, the use of existing ducts or service culverts
within bridges must be fully explored.
2 Ducts attached to the underside of bridges must not affect its load
bearing capacity, reduce the clearance or cause other issues.
3 Not all bridge structures will have the exact same installation
configuration and procedures may vary to accommodate your
specific requirements.
4 The most common method to be used will involve the use of a hydraulically operated crane fitted with a
safety basket be positioned adjacent to the bridge balustrade. From this position, workers wearing
safety harnesses can be hoisted over the balustrade and lowered into a working position as required.
5 Bracket mounting positions can now marked out on the side or underside of the bridge as directed by
the design drawings and instructions. Next, drill the holes, fit the concrete anchors and mounting
brackets and firmly secure them.
6 The steel or ultra-high-density polyvinyl chloride (UPVC) base carrier duct can now be positioned and
firmly secured.
7 The microducts can then be hauled through the newly mounted base carrier. Use a continuous length
of duct (no joints permitted).
8 Where required and as stipulated in the design instructions, both the approach and departure ends
may have to be encased in concrete where they traverse the bridge abutments and enter the ground. It
is desirable of course, for the end-product to be both safe and visually appeasing.

Trenching Near Power Cables

1 Where no physical barrier exists, no duct or cable shall be laid
within a distance of 600mm measured horizontally, nor cross within
a distance of 300mm measured vertically from any high voltage
power cable.
2 Where this separation is compromised, the duct or cable must be
separated by concrete slabs.
3 The standard protection slab is 900mm x 300mm x 75mm thick.
This slab will be reinforced with 3.55mm high tensile wires.

Duct Deviation
1 HHs / MHs typically facilitate changes in direction.
2 However, ducts may deviate from a straight line provided that:
- Individual lengths may be offset by no more than 35mm.
- The offset is in the same direction, this to avoid creating S-bends.
- The maximum overall deviation between MHs / HHs does not exceed
15˚.
3 Spacers should be used when placing multiple ducts in a trench. They prevent
ducts from twisting over and around each other. By keeping the ducts in straight
alignment, cable jetting and/or pulling tensions will be reduced.

Steep Gradient Trenching

1 Where excavations needs to be done on up-hills or declines, a layer of sand
bags should be placed at regular intervals (5m apart), to prevent the possible
wash away of backfill material.
2 Always consider the risks of land stability or earth movement, when trenching
on embankments (specialist technical investigation may be required).

15
Tree Roots
1 Tree roots exposed while trenching must not be cut unless
absolutely unavoidable.
2 Prior to undertaking tree/bush/shrub clearing/cutting as may
be necessary for trenching, approval in writing from the
relevant authority and/or property owner needs to be
obtained.
3 Never cut roots over 25mm in diameter, unless advice has been sought from the local authority.
4 Ducts are to be sleeved in steel encasing, if not 100mm away from existing tree roots.

Surface Material
1 Surface material (paving slabs, soil, grass, etc.) must be
2 kept apart by placing them on opposite sides of a
trench, where they are least likely to interfere with traffic,
pedestrians and drainage systems.
Mow-able lawn shall be cut in square blocks and put
aside and be kept moist until reinstated.
3 Where trenches pass through gardens, the contractor shall seek direction from the owner.

Duct Un-Coiling and Installation Process

1 Ducts shall not be un-coiled without the use of a Vertical or Horizontal
De-Coiler. De-coilers will prevent twisting, bending or kinking from
occurring during the installation process.
2 Duct un-coiling can be accomplished by pulling the conduit straight into
a trench from a stationary rotating de-coiler or by laying the conduit into
the trench from a forward moving de-coiler positioned on a trailer.
3 Once the duct coils are secured inside the de-coiler, only then can the containment straps on the duct
coil be cut. Next, rotate the de-coiler slowly to unwind the duct out in one plane.
4 Generally, the ducts are placed in the trench, one length at a time and be jointed on the floor of the
trench using couplers.
5 Ducts shall be laid in a straight line between MH/HHs. It is never ideal to have directional changes,
but if unavoidable - keep the bending radius as big as possible and offset is in the same direction.
6 As the ducts are laid and jointed, install end caps on ducts at all MH/HHs to prevent water and dust
from entering.
7 Care shall be taken to ensure that no dirt collects between the duct and coupler to deliver an airtight
seal.
8 At MHs or HHs where the duct goes straight-through, allow for sufficient slack for the duct to be
secured against MH or HH walls.

Moving Trailer Method

1 This method is most efficiently used where the path to be followed does not contain any obstructions
that require the duct to be placed under. Move the trailer slowly along the trench route while
unwinding and placing the duct in the trench. Take care not to over spin the reel.
Pulling Method
1 The duct can also be pulled and placed by hand or by a mechanical pulling machine with the help of
a Pulling Device that is fitted in-between duct and mechanical pulling machine. The two types of
pulling attachment devices most commonly used are a Pulling Grip or Basket Grip.

Bedding and Padding

1 Bedding is the material constituting the even (rake if necessary) floor of an
16
 excavated trench onto which ducts are laid.
2 It is desirable to pass both bedding and padding through a sieve. The
material used for bedding and padding must be of a granular, non-
cohesive nature, graded between 0.6 mm and 19 mm.

3 The compaction of padding shall be executed manually using a hand tamper. Duct buckling is much
more probable when the padding material does not provide adequate side support.

Backfill
1 After padding tampering / compaction, backfilling of the trench can be
done.
2 Material excavated from trenches may be used as backfill, provided
that it contains stones no greater than 150mm in diameter, trash, or
organic matter that could potentially damage ducts.
3 Backfill material is to be installed in layers not exceeding 300 mm, with
each layer compacted before the next is added.
4 After compacting the first layer of backfill, the warning/marking tape is placed. Take photos of this
procedure as proof of existence.

Backfilling (Concrete)
1 Check the consistency of the concrete (slump test).
2 Tamper the concrete using special care not to damage the ducts.
3 Check for cavities.
4 Allow for the concrete to cure (get hard).
5 As mentioned earlier, concrete backfill turns a once flexible duct into a long
unreinforced concrete beam of negligible strength, very likely to fracture with
ground movement. This in turn could potentially damage the duct. I ought to
point out though, that this view is not shared by everyone.

Trench Compacting
1 Once a poorly compacted layer is in place, it is difficult if not impossible to
achieve good compaction in the layers above. This is a key point, a
consequence of poor backfill compaction is high % air voids. This potentially
makes the duct vulnerable to veld fires.
2 Manual compaction is performed until the ducts are covered by both a 150mm
layer of padding and 300mm of backfill, at which point a vibratory plate
compactor can be used.
3 The compaction of the final backfill layer shall be by means of a compaction machine and shall be
compacted to a density higher than or at least equal to that of the virgin soil parallel to the trench.
4 After completion of the backfill, a DCP test must be done. This test must be documented.

Dynamic Cone Penetrometer (DCP) Test

1 As mention, on completion of the backfill process, a DCP test must be performed
and documented.
2 Test every 15m of a trench.
3 For trenches in Road Reserves or under footpaths, test every 5m of a trench.
4 Subject to a sequence of satisfactory test results, the frequency of testing may be
reduced after consulting with the relevant Authority.
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5 With a less-than 100mm penetration being the benchmark - the number of blows
are:
Verges: 2-blows | Footpaths: 3-blows | Roadways: 5-blows (or as per client spec.)

Direct-Buried Installations
1 On all direct-buried installations, Armoured Cable must be deployed -
which provides for both crush and rodent protection.
2 In general, the most desirable and economical method of cable
placement in open or rural areas is ploughing - where there likely to be
fewer obstacles to impede the progress of the ploughing equipment. In
urban or sub-urban areas where there can be many obstacles such as
underground utilities, sidewalks, road crossings etc., trenching by
hand has its advantages.
3 Should only an armoured cable be placed, a trench no wider than
375mm will do.
4 The trench shall be1.2m deep or as stipulated in the wayleave.
5 Grade off abrupt changes in terrain ahead of the plough.
6 Excavate at least 5m at the starting point, to allow for the plough to
immediately lay the cable at the correct depth.
7 Always start the plough tractor’s movement slowly and increase speed
gradually only after the cable slack is taken up from the cable delivery
system.
8 Ploughing operations must be observed continuously for: obstructions, proper feeding of the cable,
specified depth, following of the marked route, and the safety of the crew.
9 Stoppages in the plough-in process should only be for the loading of cable or marker tape and when
the terrain demands for this.
10 Warning Tape must be placed approximately 300mm below the ground surface, directly above the
cable.
11 It is critically important for MHs and HHs to be built only after the plough in of the cable. Pre-fabricated
HHs are often utilised.
12 Each section, after ploughed-in, must be checked with an OTDR for possible damage.
13 After the plough in process is completed, the trench must be levelled by one of the following methods:
- Back blading with the plough-in machine.
- Using a TLB to level the disturbed areas.
14 The National Electrical Code (NEC) recommends that non-current carrying armour shields and
metallic strength members be bonded and grounded.

Earthing, Bonding and Surge Protection

1 The armouring of optical fibre cables shall be lugged and bonded to an earth bar using a soft multi-
stranded 6mm² green / yellow insulated bonding cable. Bonding cables shall be kept as short as
practically possible and must contain no sharp bends.
2 Proper grounding and bonding is required for the safe and effective dissipation of unwanted
electrical current, and it promotes personal and site safety. Typically, optical fibre cables do not
carry electrical power, but the metallic components of a conductive cable are capable of
transmitting current.
3 When the armoured cable is correctly bonded and grounded, it minimizes the risk of unwanted
18
 electrical current that could potentially harm personnel, property or equipment.
4 Required…
- By electrical codes
- By equipment manufactures
- To protect personnel
- To protect equipment

The difference between the terms bonding and grounding:

1 Bonding is the multiple connections to metallic parts (at every joint), required to form a continuous
electrical path.
2 Grounding is the act of connecting that path to an earth.

The Procedure
1 Use a cable knife to score the outer sheath of the armoured
cable approximately 25 mm (1 inch) long. Take care not to
damage the inner sheath.

2 Slide the base plate under the armour.

3 Place the top plate over the base plate and tighten down the
lock nut.

4 Cover the grounding clamp and split portion of the sheath

with vinyl tape and connect to the ground system or bond
thru.

Markers
1 Underground routes must be marked with identifiable markers.
2 GPS coordinates of all MHs / HHs must be taken and documented to form part of the
as-built documents.
3 These markers shall have a length of not less than 1.8m and a diameter of not less
than 100mm.
4 The MH and HH markers shall be planted 600 mm deep, opposite them and be well
compacted.
5 A passive marker can be buried at key points during construction or used to mark existing facilities.

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Manholes and Handholes
1 MHs and HHs shall be positioned as far away as possible from road
junctions.
2 MHs and HHs must to be built according to prescribed dimensions and
specifications.
3 Before any concrete is placed the Contractor shall examine the shuttering
for firmness and correctness of position and remove all dirt and other
foreign matter.
4 Hand mixing of concrete is permitted in exceptional cases but only with
written permission of the client.
5 Concrete mix shall be such that a strength of 20MPa (2.5:2.5:1) is
obtained 28 days after pouring.
6 Duct entry points into HHs / MHs must be drilled, without cracking or
damaging the surrounding structure.
7 Ducts shall enter and exit HHs / MHs in line with the direction of the route,
for them to be coupled thru without any obvious effort, as a continuous
duct.
8 Ducts must never enter and exit on the same wall.

9 HH / MH external labeling should be done on the coping and NOT the lid, as lids can get damaged
and be replaced. GPS coordinates must be recorded.
10 On completion of a HH / MH, the Contractor shall re-instate the area around the HH / MH to its
original state or better.
11 HH / MH covers shall be finished flush with the surface area.

Where bricks are used to construct HHs the following must apply:
- Written permission obtained from the client.
- Use only baked quality clay bricks sourced from an approved manufacturer.
- Re-enforce every third layer of bricks.
- The wall thickness must be double brick or better.
- The outer wall must be waterproofed.
- Use an approved footway-type or roadway-type frame and cover.

HH / MH Inspection
1 Splice closures are secured.
2 Cable slack neatly stored and secured with no compromise to the bending radius.
3 Left tidy and clean.
4 Ducts sealed in-between wall.
5 End Caps fitted to empty ducts.
6 Used ducts sealed in-between cable and duct.
7 Cables and ducts are clearly labelled.
8 HH / MH clearly marked on the coping.
9 Locating disk in position.

Safe HH / MH Working Procedures

1 Obtain a HH / MH entry ref for the work to be undertaken.
2 At least 2-persons must be present before entering a MH.
3 Ensure that the vehicles are parked in such a manner that they do not create an obstruction or hazard
to traffic and/or pedestrians.
4 Use barricades and cones that are clearly visible around the HH / MH.
5 Pour water around the lid of the HH / MH, to prevent creating a spark when opening it.
20
6 Lift HH / MH covers using your legs and place the cover at least 2m away from the opening.
7 Before entering the confined space, test at 3-levels (bottom, middle, and top) for:
- Oxygen content
- Flammable or explosive gases
- Hydrogen sulphide
- Each level must be tested for a minimum of 60 seconds.
- Use only an approved calibrated gas detector.
8 Ensure that the gas detector is in operation the entire time spent in the MH.
9 An aluminium ladder in good operating condition must be used to enter the MH.
10 Raise or lower tools and/or equipment into a MH using a rope or bucket.
11 Never place equipment or tools near the edge of a HH / MH.
12 Constant ventilation is required when performing work within a MH.
13 Never fusion splice in a HH or MH.

Trenchless Methods
Directional Boring
1 In very simple terms, directional drilling (also known as horizontal directional drilling) is a drilling
process where a drill head is steered underground. This method is adopted by all companies but it is
typically sub-contracted as many companies do not own these somewhat expensive drills.
2 Directional boring is the preferred method to cross roads, highways, railway lines, rivers and all
other services that may prove to be too dangerous or costly to cross using conventional methods
like trenching or ploughing.
3 In horizontal directional drilling there are three installation stages:
i. Pilot drilling
ii. Reaming the initial pilot hole
iii. Pulling back the duct in the reamed borehole
4 The course of the drill is monitored and can be controlled as rods progress following an upward
sloping path, before emerging at an intended point.
5 The drill head is then removed and replaced with a back reamer, ± 20% larger than the duct or cable
to be pulled into the hole.
The duct is attached to a swivel connection on the back reamer. The drill-rods and reamer are
rotated and pulled through the hole, enlarging it and pulling-in the duct at the same time.
The whole operation is carried out with pressurized drilling mud, which both carries away the spoil
and supports the hole.
6 Rigs capable of drilling up to 300 metres in one drill are available and various sizes of ducts can be
installed with this equipment.
7 The covering must not be less than three times the final diameter of the drilling hole and at a
minimum of 1.5m.
8 At river crossings the distance between the bottom of the water and the drilling hole should be 10-
times the diameter of the pipe and not less than 3m.
9 Soil removal during the drilling process is the responsibility of the contractor.
10 If the accuracy of the drilling is not specified in the wayleave, the area in which the drilling may

21
 wander should not exceed a 40mm diameter around the predetermined axis.
11 As always, the location and depth of underground services must be pre-determined before drilling
can commence - as sudden deviations are not possible to bypass obstacles.

Hammerhead Mole
1 Hammerhead Moles provide a cost effective alternative to horizontal drilling. They are apparently
easy to use, simultaneously boring and installing a duct.
2 To begin with, both an entrance and exit trench or hole must be dug at the allocated positions.
3 The Hammerhead Mole is then inserted into the abovementioned hole in the direction of boring and
the boring process commences. A duct-pulling attachment allows for the duct to be installed at the
same time the bore is made.

Reinstatements
1 Reinstatement work must be done by The Roads & Storm Water Department
unless a wayleave indicates otherwise.
2 Should the wayleave holder do the permanent reinstatement, a 12-month
guarantee period commences from the date of completion.
OR
Should the wayleave holder do a temporary reinstatement, a 2-week
maintenance period commences from the date of completion.
3 Grassed areas shall be reinstated using the original turf, replacement turf or an equivalent seed.
4 Any constructed footway must be reinstated with the same surfacing materials that existed originally
(e.g. concrete blocks, slabs, etc.). Material may be reused if undamaged, or else replaced with
similar material.
5 Remedial work will be required if any of the following defects exists: depressions (resulting in
22
 standing water), humps (crowning), edge depression or cracking.
6 Any excavation left unattended for a period of more than 5-days can be made safe by the road
authority and charged to the contractor.

Cable Pre-installation Procedures

The following items are key considerations:
Pre-test with an Optical Time-Domain Reflectometer (OTDR)
1 All optical fibre cables must be tested while on the drum, prior to deployment. A Bullet or Divot Bare
Fibre Adapter is to be used to connect fibres to the OTDR.
2 Testing shall be done on all fibres in one direction at 1550nm, using a pulse width of 30ns. Traces
must be stored and an electronic copy submitted to the project manager.
3 Should a cable be installed without an OTDR pre-test, the smart money is on the supplier not
accepting a return on the cable. This is because a supplier can claim that the installer assumed
liability upon installation (i.e. responsible for the damage).

Pre-installation Cable Inspection

1 Always wear protective gloves and safety boots (with steel toe caps) when handling drums.
2 Check that the cable specified, has been procured.
3 Inspect the cable drum for signs of excessive weathering and/or damage.
4 Drums must be transported or stored with their battens intact.
5 Do not accept delivery of an optical fibre cable should the drum is damaged.
6 The plastic foil wrap must remain in place until cable placement.
7 When removing the plastic foil wrap on the cable, do not use sharp tools that could potentially
damage the cable jacket.
8 Ensure that the cable drum bolts are all tightened.
9 Verify that nails, bolts or screws on the inside surface of drum flanges are counter-sunk to avoid
damage to the cable during placement.
10 Place the cable drum in line with the intended direction of deployment, in order to prevent the cable
from rubbing against the reel flange.
11 Cable ends must always be sealed – using pre-formed or heat shrinkable end caps. Using tape for
sealing cable ends is considered unsuitable.
12 Should the drum be rolled for some reason, always do so following the direction of the arrow.
13 Drums on site, must be chocked to prevent them from moving or rolling.

Cable pay-off - over the top or from the bottom?

Over the top for:
- Jetting / blowing cable
- Hauling cable
- Figure-eighting cable
- Erecting cable

23
However, a case can be made for from the bottom, when jetting / blowing cable. This simply reinforces
our conviction that ultimately, faced with this choice, a Contractor must determine which option is
favoured by the Network Owner.

Introduction to Air-Assisted Installations

Few (if any) would dispute that the foundation of the value proposition associated with blown fibre systems,
is its low cost fibre upgrade capability i.e. adding fibre cables to unused micro-tubes.
Jetting and blowing are two probable air-assisted cable installation techniques. Both methods require
pushing the cable with a tractor mechanism while blowing compressed air into a preinstalled duct along the
cable being installed. Both rely on air flow to help “float” the cable inside the duct and a result, minimizing
sidewall pressures and reducing friction between the cable and the duct.
When jetting or blowing, you're combining a pulling force (compressed air) with a pushing force
(hydraulically or pneumatically driven tracks) during the installation, providing an efficient, stress-free
deployment in far greater increments than possible when hauling cable.
Jetting and blowing differ in how pulling force is applied to the cable. Jetting uses a missile (parachute) at
the front end of the cable. A differential pressure across the missile head creates a pulling force on the
cable. Blowing does not use a missile - instead, the pulling force on the cable is due to fluid drag of air
rushing along the cable - this pulling force is distributed along the cable length. A mechanical pushing
device is common in both methods.

It is common wisdom that hydraulics can give you higher forces than pneumatics. Mindful of this, a blowing
machine with a pneumatic drive is recommended for cables up to 15mm in diameter and a blowing
machine with a hydraulic drive is recommended for cables with a diameter in the range from 14 - 32mm.
The key parameters when installing fibre cable in ducts are blowing distance and time. 1000 to 2000m is a
typical blowing length. Typical installation speeds are 40-50 meters per minute under an air pressure of 10
bars. Most routes can be blown with a 10 bar supply.
Smaller diameter and lower weight cables make possible larger blowing distances. The maximum cable
push force will decrease as the duct inside diameter increases, reducing the achievable blowing distances.

Survey the complete route prior to blowing in order to determine:

1 The location of HHs / MHs.
2 Determine distances between HH / MHs.
3 Determine where coupling of ducts are necessary.
4 Accessibility of terrain for the use of the intermediate (mid-point) fibre blowing equipment.
24
5 Identify specified ducts to be utilised.
6 Be sure to consider the accessibility of HHs / MHs to the splicing vehicles.

Jetting / Blowing the right cable

1 Choosing the right cable is extremely important for any installation. Strictly speaking, the purpose of
the cable is to protect the fibres during installation and the service lifetime. Cables share some but
not all characteristics and you need to ensure you install the cable type appropriate for the
application.
2 Micro cables are designed with high-density polyethylene (HDPE) outer sheaths to minimize friction
with the inner surface of micro ducts. They are also designed with the necessary stiffness
properties to resist buckling forces and to negotiate changes in direction.
3 The cable on the drum must be covered until just prior to installation to protect the jacket from
exposure to the sun.

Suggested Air-Assisted Installation Practices

Cable drums are typically supplied containing 4-km of cable. Mindful of this, drums are placed midway of a
4-km length. There’s plenty of evidence suggesting that the most efficient cable installation would involve
two 2-km jetting shots (A to B followed by A to C). After jetting A to B, a ‘figure-8’ will be created at the
midway point, to gain access to the end point of the cable previously on the drum. Next, the figure-8 end
will be jetted in the other direction. This figure-8 puts a half twist in on one side of the 8 and takes it out on
the other, preventing twists.
With a little bit of good fortune, we ought to be able to install 4-km of cable in one placement of the cable
drum and blowing equipment… consisting of; 2-km of cable jetting - 2-km of "figure-eighting" – concluded
with 2-km of cable jetting. If so, great. But wait, at some point the cable movement could slow down during
the blowing process - then instead of taking a 2-km shot, the jetting shot could for example, be reduced to
only 1-km. This of course, would call for a second ‘figure-8’ to be made at the 1-km mark.

Jetting machine settings such as air pressure, flow rates, speed, grip wheel tension etc. will be determined
and provided by the blowing equipment supplier.

Duct Integrity Testing (DIT)

Cable jetting / blowing machines don't work unless you have an air-tight duct.
1 Air Testing - microduct continuity checking:
- Run the compressor at 10 bars for 5min.
- Good airflow at the far-end indicates that continuity is OK.
2 Foam Sponge Testing - cleaning the duct:
25
 - Wet the sponge slightly with blowing lubricant.
- Place the tight-fitting foam sponge inside the microduct.
- At a pressure of 10 bars, blow the sponge through the microduct.
- If excess water or dirt exits the microduct, repeat the process.
- Have a DIT catcher in place at the far end to catch the sponge when it emerges.
- A sponge is typically ± 50mm in length and its diameter must be 2 X the duct ID.
3 Shuttle Blowing - check for bends, kinks or blockages:
- Use a shuttle with an OD no more than 80% of the microduct ID
- At the receiving end, a DIT catcher must be used.
- Note that a flying shuttle can cause injury and/or damage!
4 Pressure Test - check for coupler leaks or microduct punctures:
- Terminate both ends of the microduct with valve connectors.
- Build up pressure to 5 bars and close the inlet valve - repeat this until the pressure has
settled.
- Should the pressure not drop below 4.5 bars within 30min – this test is passed.
5 If the duct fails DIT tests, consult with the relevant authority on whether to use an alternative duct or
to repair of the designated duct.

Micro Duct Fill Ratio

1 For optimum jetting / blowing performance, ensure that your cable-to-duct diameter fill ratio does
not exceed 76%. This is determined and provided by the microduct supplier. It is wise to always
verify this by checking the provided spec sheet.

Cable Blowing Lubricants

1 Adding a small amount of lubricant to a tight-fitting foam carrier
(sponge) before blowing it through the duct, will provide an open and
lubricated pathway. It is argued to give better results compared to
coating both the duct and cable with lubricant. Odd, huh? Let me try to
explain. Lubricant on a cable jacket, apparently makes it too "slippery"
for optimal laminar-flow jetting.
2 Let’s not forget that the air "pushes" on the jacket through friction. A too low friction jacket will not
easily be pushed with air. Normally, as little as 0.25 litre of lubricant is required to coat 2km of
cable.

Suggested Air-Assisted Installation Practices

1 It is desirable to blow downhill wherever possible.
2 DIT results must be available prior to blowing the cable.
3 Always measure the cable diameter before jetting, to select the correct
spacers. The cable must lie snug in the V-groove between the drive rollers.
4 To ensure that the cable is not prone to slipping, push and pull the cable
through the machine by hand a few times to ensure that the cable is seated
properly in the drive rollers.
5 The cable must always enter the jetting machine under no tension and in a
straight line.
6 The cable must be clean as it enters the blowing equipment to allow for
effective gripping of the driving wheels. Contamination of the cable will
26
 cause unwanted friction and result in a reduced blowing distance.

7 Monitor the speed and torque of the blowing machine as the cable is blown to ensure that the cable
jacket is not damaged by the driving wheels.
8 One person must control the cable reel and be prepared for emergency stops.
9 Always note the meter reading on the cable and zero the blowing machine distance meter, prior to
blowing.
10 Always establish two-way communication during the fibre deployment process at crucial points along
the cable route.
11 The blowing machine should have an automatic shut-off feature that controls the push force applied to
the cable. With this feature, cable and duct damage can be prevented should the cable stop abruptly
within the micro duct.
12 Ensure that when connecting the transportation duct to the blowing machine, it is not entangled with
the new or existing cable/s.
13 The ‘figure-8’ must be laid on a ground sheet and care must be taken to ensure that the cable does
not touch the ground as it is fed into the machine.
14 To protect the end of the cable and also to guide the cable along its desired route, a bullet must be
used.
15 As mentioned, blowing lubricant reduces the frictional drag on both cable and in the duct thus
increasing the achievable distance.
16 To ensure that the blowing equipment remains in good working condition - after a week of continuous
blowing - machine maintenance must be performed.

Management of Cable Slack

1 When handling cable, always wear; protective overall, gloves and safety boots.
2 Never exceed the recommended cable bend radius:
10 x Cable OD - No Tension (installed)
20 x Cable OD - Under Tension (being installed)

27
3 What is the minimum bend radius of your microducts?
There is a simple formula: Radius min = 10 x OD
Therefore, if you have microduct has a OD of 10mm, your Radius min = 100mm
4 A total length of 17m (15m for slack and 2m for splicing) of cable slack is traditionally required in a
HH or MH housing a splice enclosure. Be sure to consider the accessibility of HHs / MHs to splicing
vehicles.
5 Install slack brackets on HH / MH walls to secure cables.
6 The slack in the HH or MH needs to be tied together using a tie wrap or PVC tape at 1m intervals.
7 The fibre cable slack inside the HH / MH must be coiled in a ‘clock-wise’ direction with minimal back
tension.
8 Ensure that the slack of one splice closure does not become inter-twined with the slack of other
splice closures in the HH / MH.
9 Bundle cables together in groups of relevance.
10 Do not route cables in such a manner that they block ducts.
11 Used ducts must be sealed between cable and duct.
12 Cable slack typically adds 2% to the overall distance. Thus a 100-km link is likely to contain as much
as ± 102 Km’s of cable.

Figure-eighting
1 The preferred size of a figure-8 is about 5m in length, with each loop about
2.5m in diameter. To start with, set up two traffic cones 5m apart – then pay the
cable off the top of the reel and loosely weave it around the cones in a figure-8
pattern - on top of a groundsheet. Large relaxed loops will help prevent the
cable from becoming entangled.
2 Continue to figure-8 the cable until the remainder of the reel is played off.
3 In order to pull from the figure-8 - it is necessary to flip it over, a task that requires a minimum of three
people - one at the centre and one at each end. The required cable end will now be at the top of the
figure-8.

Micro Duct Tools and Accessories

28
Tools
Ensure that installers are fully educated on the proper use and
operation of any tool before starting a job.
It is essential to always use the prescribed cutting tools to produce
a clean and straight cut to a microduct, before inserting a coupler.

Bullet
Fixed to the end of the fibre cable before blowing starts, to guide
the cable through the microduct.

Cleaning Sponge
Used for removing dirt and/or moisture from a microduct.

Shuttle
Used to check the microduct for bends, kinks or blockages.

Caps & Plugs

Used for the permanent or temporarily sealing of unused
microducts to prevent water and dust from getting in.
Use only the prescribed connectors and end-plugs.
Couplers
Used for the air-tight coupling of microducts.

De-bur Tool
Allows for one to round-off a microduct after cutting - before adding
a coupler - this will produce an air-tight connection.

Locking Tool
Used to firmly lock the microduct into a connector.

Cable Carriers
Parachutes capture the air within a duct, tugging along with it the
cable. In the absence of air pressure, they collapse allowing for
easy pullback. An alternative is to use an Inflatable Carrier.

Aerial Works

29
Some areas may call for everything to be underground, while unquestionably, some situations will call for
aerial installations.
Pole Handling PPE
1 Safety boots with steel caps.
Protective clothing with long sleeves.
Shoulder pads.
Gloves.
Hardhat.

Transportation of Poles
1 Poles must never exceed the 0.5m vehicle overhang and must have a red flag secured on the
overhanging end.
2 Poles that are loaded onto a pole carrier must be secured to ensure that the cargo does not move
while it is in transit.

Pole Off-Loading Procedure

1 Ensure that the removal of any one pole will not cause shifting or rolling of any of the remaining
poles.
2 Step 1: Unfasten the poles.
Step 2: Slide one pole at a time towards the rear end of the vehicle.
Step 3: When the pole reaches its equilibrium point, the persons on the vehicle need raise their end
slowly.
Step 4: The persons on the ground pull the pole until 1m of it is left on the back of the vehicle bed.
Step 5: The persons on the ground receive the pole and gently place it on the ground.
3 A pole must never be dropped on the ground, as this could damage the pole and/or cause injury to
team members.

Pole Handling Ratios

1 7m pole = 4 people
8m pole = 6 people
9m pole = 8 people or a mechanical aid
10m pole = mechanical aid.
11m + pole = mechanical aid

Climbing Ladders
1 Keep hands free of tools or materials when climbing or descending a pole or ladder.
2 Workers climbing up or down ladders must always face the ladder and maintain a 3-point contact.
This effectively means that 2-hands and 1-foot or 2-feet and 1-hand must be on the ladder at all
times.
3 Ladder must be positioned correctly (1-4 ratio).
4 Ladder must be properly secured (lashed and held).
5 Ladder must be in a good condition.
6 Ladder must suit the application.
7 A worker must be correctly positioned on the ladder.
8 A safety belt must be worn and secured to the pole.
9 Never climb intermediate poles if the span they support is being placed under tension.

30
Survey
1 Survey rods should be planted in line at selected pole positions so that,
when erected, the poles will be in a straight line.
2 A spirit level should be used to verify that there is no lean to the rods.
3 As the survey advances, the rear rods used for lining up - will be
withdrawn and survey pegs driven into the ground in the exact position
previously occupied by the survey rod.
4 The location of the poles to be erected along roads shall be in accordance
with the way leave drawings and conditions stipulated by the authorities
concerned.
5 Square wooden pegs shall be used to mark the position of every pole,
stay or strut.
6 The numbering (or other details) and marking of the wooden pegs shall be
done as agreed upon by both the client and contractor.
7 The tops of pegs that show the positions of angle poles must be marked
with blue lumber crayon crosses.
8 A survey peg for a strut position, must show the approximate spread of the strut.

Survey Equipment and Tools

1 Digital camera spare batteries.
2 GPS with tracking function and spare batteries.
3 DCP tester.
4 Tape measure.
5 Measuring wheel.
6 Road cones.
7 Clip board, survey sheet/note book and stationary.
8 Construction vehicle – with signage and an orange light mounted on the rooftop.
9 Road map and/or proposed route detail drawing/s from the client.
10 Reflector jacket.
11 Personal Identification.

Survey - Gather Route Information

1 The information on this route must accurately indicate distances.
2 Take photos of all obstacles on the route (existing services, bridge crossings, rocky areas, buildings,
built-up areas, paved/tarred areas, wetlands, overhead obstacles, etc.).
3 Identify all obvious landmarks where the route changes direction (take photos).
4 Note down any road repair work necessary - record distances and GPS coordinates.
5 Provide for a series of DCP test readings along the route and document the exact positions.
6 Description of the topography along the route (sloping, edge of cliff, adjacent to lake, forest
surroundings, rivers, swampy areas, etc.) - record distances and GPS coordinates.
7 Description of the ground condition along the route and distances (rocky, sandy, grassy, clay, etc.) -
record distances and GPS coordinates.
8 Indicate the distance to the nearest town, where the civil works material (sand, cement, stone,
water, tools, etc.) can be sourced from.
9 Locate possible warehouse/camp sites where material can safely be stored.
10 Indicate the availability of hospitals/clinics/police along the route - in case required during
operational activities.
11 Plan the route to allow for projected road or rail deviations.
12 Double-check recorded details on the return journey.

31
Pre-Install Meeting

A pre-install meeting or meetings must be held to discuss the survey results, the optimum pulling sites,
span lengths, installation equipment and hardware requirements, logistics, splice locations, terrain and
other vital installation topics.

Checks to be undertaken prior to commencing with the planned aerial work

1 Does the contractor have approved aerial route drawings, signed by the client?
2 Do the drawings show the alignment of the aerial route within the wayleave specification?
3 Are the wayleaves in place? (copies and drawings must be on site at all times).
4 Have the locations of existing services been marked and shown on drawings?
5 Are the aerial route drawings being marked indicated on which side of existing road/pathway to
stay?
6 Has the accessibility of poles to splicing vehicles been considered?
7 Does the cable have a UV resistant cable jacket?

Wooden pole inspection (prior to planting)

1 Correct type of pole supplied? (length and thickness)
2 Are the poles chemically treated? (creosote, tarred)
3 Excessively bent or cracked poles should never be used. Horizontal cracks perpendicular to the grain
of the wood may weaken the pole. One large knot or several smaller ones at the same height on the
pole may be evidence of a weak point on the pole.
4 Inspect the pole for evidence of termites or ants.
5 Ensure that all poles are fitted with ‘end plates’ and strapping at both ends.
6 The poles should never be off loaded and stacked on the ground for long periods as this could cause
damage to the poles as well as the environment.
7 Hammer Test (existing poles): Rap the pole sharply with a hammer weighing about 1kg, starting near
the ground line – then continue upwards around the pole to a height of approximately 1.5m. The
hammer will produce a clear sound and rebound sharply when striking sound wood. Decayed areas
will be indicated by a dull sound or a less pronounced hammer rebound.

Hole-digging Tools
1 The tools provided for hole-digging include picks, shovels, earth
augers, crowbars, drills and sledge hammers. The tools to be used
for any particular work are determined predominantly by soil
conditions.
2 On large projects and wherever ground conditions permit,
hydraulically powered Earth Augers can be used. It looks much like a
corkscrew and produces extremely clean holes.

Pole Holes
1 All excavations for pole holes will be such that the survey peg
indicates the centre of the hole.
2 If the holes are too large, the soil will be unnecessarily disturbed and
the poles will not be supported by solid earth. (A diameter of
approximately 400 mm is recommended).
3 Where a hole is dug on sloping ground, the depth of the hole shall be measured from the lowest point
on the ground surface.
4 In extreme rocky conditions where holes cannot be excavated to the specified depth, an arrangement
between contractor and client can be reached for poles to be set in concrete.

32
Poles set in Concrete
1 Where poles are planted in soil that is difficult to compact, such as sand and
swampy areas and in extreme rocky conditions, the poles can be cast in
concrete.
2 Only new wooden poles can be set in concrete.
3 The hole must be circular in shape. The hole diameter must be kept to a
minimum, but be sufficiently wide to accommodate at least 85mm of concrete
between the sides of the pole and the undisturbed ground.
4 The concrete to be used must be made from a mixture of 1 part cement, three
parts sand and three parts crushed stone (1:3:3 mix - 15MPa).
5 Concrete must not be compacted around the poles, but thoroughly tamped
around the pole with a suitable wooden stick, until the hole is filled.

Pole Spacing
1 It is advisable to maintain a uniform span length and depart from this only when it is rendered
necessary by conditions such as: (1) uneven ground (2) sharp bends (3) or to avoid dangerous
positions. This may necessitate the planting of additional poles or omitting of poles.
2 Steel measuring wires for standard span lengths should be made up locally. When the length of span
has been chosen the appropriate wire should be used to determine the distance between successive
poles. A steel tape measure should be used for checking the length of the measuring wire daily during
the survey.
ADSS Span Lengths
Type of route (m)
Short span 83
Medium span 250
Long span 500

Pole Planting Process

1 Ensure that all holes necessary for pole dressing are drilled prior to erection.
2 A pole should be erected by laying it on the ground in such a position that by raising the top section,
3 the base should slide into the hole.
4 Backfilling and ramming must take place in 300mm intervals.
5 Where stones are available they should be used to stiffen the holding.
During the backfill and ramming process, always ensure that the plumbness of the pole is
maintained.

Suggested Pole Planting Work Practices

1 Avoid dongas, culverts, drains or water channels.
2 Avoid obstructing private roads and entrances.
3 Restrict road crossings to a bare minimum, and if possible, stick to the same side of the road
throughout.
4 Avoid trees and where not possible, select a position which will minimise interference from trees –
even at the expense of construction costs being increased slightly by this action.
5 Along national and other proclaimed roads the poles and stays should be located in the position
agreed to by the Road Authority and as indicated on the wayleave.
6 Keep the route as far away as practically possible from power lines.
7 Where the ground is very soft, poles may be planted 300mm deeper than specified, but only if the
necessary vertical clearance is maintained.
8 Ensure that all holes necessary for pole dressing are drilled prior to erection.

33
 9 Maintain a distance of at least 1m from trigonometrical beacons and stations.
10 If locating the pole route more than 1m within the road-reserve boundary can reduce the cutting of
trees and future interference by trees, the matter should be discussed with the Roads Engineer with
a view to obtaining approval for the increased encroachment.
11 The principle to be followed in all cases is that neither stays nor poles are to be planted where they
are likely to cause obstruction or to be dangerous to users of the road, or where they are likely to
interfere with ordinary road maintenance such as the clearing and trimming of the edges of the road
or the cutting of drains, gutters, etc.
12 In railway reserves, the poles should be located as close as possible to the boundary fence.

Types of Stays
Terminal stays
Provided where the route starts and ends. This stay must be on the side of the pole opposite to the
direction of the cable route.
Line stays
Installed at every 13th pole along the route or spaced alternatively as per specification. Line stays must
be installed on poles either side of rivers and road crossings where normal span lengths are exceeded.
Angle stays
Used to counter-act a change in direction of the cable route by more than 15˚ or as per client specs.
Wind stays
Used to stabilize a cable route against wind. Fitted at 90˚ against the direction of the cable route and on
either side of a pole.
Tubular Stays
Has a shorter spread than an ordinary stay and used where and ordinary stay would:
- Have insufficient spread.
- Create a traffic hazard.
- Obstruct a road entrance.
- Where the property owner objects to the fitting of an ordinary stay.
Stay Guards
Stay guards (225mm wide painted black and white bands) must be fitted on all stays, potentially exposed
to pedestrians and/or vehicles.

Struts
Struts can be used as an alternative where stays create traffic hazards, block roads or
where a property owner objects to the fitting of a stay.
Struts must be installed on the opposite side of where an angle stay would have been
fitted, to counter-act the cable strain.

Stay Holes
1 The cross-section of the hole shall be confined to the smallest
size necessary to accommodate a stay plate.
2 The depth of stay holes shall be 1.5 meters or at such a depth
where the unthreaded portion of the stay rod protrudes by no
more than 25mm above ground level.
3 Stay rods without plates may be used where solid rock is
encountered. The stay rod is now inserted in a hole drilled into
the rock and secured with cement.
4 In difficult to dig ground conditions shallower holes are allowed
subject to approval and shall then be backfilled using concrete.

34
Spread / Height Ratio
1 The spread is the distance from the foot of the pole to
the point to where the stay enters the ground.
2 The height is the distance from the ground to the pole Height
Height

attachment. Spread
Height

3 Wind stays shall have a spread/height ratio of 0.6:1 Spread

Spread
4 Terminal and line stays has a spread/height ratio of
Stay
1:1 Stay a
below
Stays on Slopes
pull o

Termination of Stay Wire to Pole or Crosshead

1 Wrap the top pre-formed “make-off” without overlapping around
the pole twice at the prescribed height with ends meeting. 150 mm

2 Twist the top of the preformed “make-off” around the stay wire.
300 mm
3 Cut the stay wire at the correct length to ensure that the proper
spread/height ratio is maintained. 150 mm
4 Place the bottom of the preformed “make-off” through the
crosshead eye. Make - off
Preformed Top
5 Then pull tight and cut the suspension wire in line with the
crosshead and twist the bottom preformed “make-off” around the
stay wire (ensure that the crosshead is threaded to the outer most
of the stay rod).

SIDE ELEVATION

35
Aerial Cable All-Dielectric Self-Supporting (ADSS) Installation
Self-supporting cables are reinforced with internal strength members to support their own weight.
Installation 2-Methods
1. Installation Process (Conventional Method)
1 To start with, a UV resistant cable jacket is required for all aerial applications.
2 Orientate the drum so that the natural payoff direction faces the pulling direction.
3 To eliminate possible cable contact with the ground, play the cable off from the top of the drum.
4 Fit specially designed cable pulley boxes to every pole on the route, for the length of cable to be
erected.
5 Feed the pulling rope through these pulleys. It is extremely important that the pulling rope and the
ADSS cable have the same diameter.
6 Make a hauling eye at the end of the cable by removing a piece of the cable sheath (250-300mm).
Next, the Kevlar of the cable is then wound around the cable and attached to the cable using a 25/8
heat shrink sleeve.
7 Place the drum at least 50m away from the pole where the cable is to go through the first pulley.
This will prevent the cable from bending too much while being pulled.
8 Attach a break-away swivel to the end of the hauling rope and then attach the other end of the
break-away swivel to the hauling eye of the cable - erecting can now begin.
9 Cable lengths of up to 6000 m can be erected with one haul if the terrain allows for it.
10 Radio Communication between persons at the drum, alongside the cable-end and the hauling team
must be maintained.
11 When hauling the cable, a person with a two-way radio must walk alongside the cable-end to ensure
that the cable is not twisting with the rope, especially at angle-poles.
12 The hauling team must haul the cable evenly and prevent jerking. The person(s) at the cable drum
must "feed" the cable off the drum at the same speed at which the cable is being hauled. There
must be no strain on the cable between the drum and the first pulley.
13 A good rule of thumb is to keep the pulling tension to ½ that of the sagging tension (see sagging).

2. Installation Process (Figure 8 method)

1 This method should be used only when the terrain is such that the conventional method cannot be
used. Place the drum approximately halfway along a long hauling section.
2 Follow steps (1) to (8) as described above (Conventional Method).
3 The one half of the cable length is hauled in the one direction.
4 The balance of the cable is then completely run off the drum into a figure 8 on a tarpaulin, after
which it is hauled in the opposite direction.
5 The figure 8 method should not be used for cables longer than 4000 metres as it becomes risky to
manage a coil longer than 2000m, without possibly damaging the cable.

Power crossings
1 Where the crossing of telephone and power routes is unavoidable the angle of crossing should be
as near to a right angle as possible. The following deviations from a right angle are permissible:
2 Type of Power Route Maximum Allowable Deviation From 90°
Below 48 kV 45°
48 kV and above 30°

36
Ground Clearance
Location of route crossing Clearance (m)
1 Non-electrified railways 6.1
2 National road 6.5
3 Abnormal provincial roads 7.5
4 Other provincial roads 6.1
5 Public roads 6.1
7 Private roads or railway tracks to in or near towns 4.9
8 Roads or privately owned railway lines or near towns 3.7
9 Country roads or railway lines, or over veiled or private lands other than (10) 3.7
10 Cultivated farmlands and across points of entry in cultivated lands 4.9

Local Thimble Type Dead-End Sizes

Cable Dia. (mm) Colour Code
9.2 - 9.5 Black
10.4 - 10.8 Red
11.5 - 12.2 White
In order not to damage the cable jacket, it is immensely important to use the correct size dead-end, NB,
colour codes differ from supplier-to-supplier.

ADSS Terminations and Support Types

1 Where an aerial cable ends (i.e. goes underground or into a splice
False Termination
joint), it is a True Termination. If the span continues (i.e. the cable is
not cut) and is called a False Termination.
2 Where do we find False Terminations? On either side of road
crossings | Every 500m (or as per client spec) | ≤ 10° angles (or as per
client spec).
3 At False Terminations, a 100mm loop (goose neck, drip loop) in the
cable, must be left at the pole between the two dead-ends.
4 At an angled pole, the cable must always pass on the front of the pole
- never behind.
5 To support the cable at intermediate poles, simply attach a support clamp to the S-hook.
6 After the cable is terminated, wait for a while, plus/minus 10min to allow the cable to stabilise, before
securing the cable in the support clamp, for intermediate support.

37
Securing of Cable to Poles (Termination)
1 Break-away swivels are used alone or in conjunction with dynamometers to ensure
that the maximum pulling tension is not exceeded.
2 To terminate the cable at a terminal pole (beginning or end of route), a preformed
dead-end, is wrapped around the cable and hooked onto a single S-hook.
3 With several sizes available, ensure that the correct size dead-end is used.
4 The (17m or so, on each cable) splicing slack is then coiled in a 500mm coil and
secured to the pole as high as possible from the ground. Start coiling by rolling the
slack cable like a wheel. This will ensure that no twists are put in the slack, which
could result in the fibres being damaged.
5 When a route deviates with an angle ≤ 10°, the cable must be terminated as follows:
a. Fit a double S-hook on the angle-pole.
b. Wrap a temporary dead-end around the cable beyond the angle-pole.
c. A number of workers must then pull on the rope until the desired tension is obtained.
d. While the tension is held steady, a person on top of the pole wraps a dead-end around the
cable and hooks it onto the S-hook.
e. Remove the temporary dead-end from cable.
f. A dead-end is then wrapped around the cable in the opposite direction and hooked onto the
termination hook.
g. As mentioned, a 100mm diameter loop (goose neck, drip loop) in the cable, must be left at
the pole between the two dead-ends.

ADSS Sagging - Line of Sight Method

1 The installation sag is typically 1% of a span length. Less sag, will require stronger cables.
2 To my knowledge, the ‘line of sight’ method is our best option.
The approach taken here requires for the exact distance between poles to be established. 50m as
shown in the example below. In essence, the far-side pole is marked using bright coloured tape with
the appropriate mid-span sag distance from the attachment height i.e. .5m (1% of 50m).
Next, the installer returns to the first pole and places his/her line of sight at that same height as the
marker tape on the second pole, to line-up the mid-span sag distance.
This person must have radio contact with the team tensioning the cable and give instructions of how
much to tighten the cable, for the belly of the sag to rise and match the coloured tape mark on the
opposite pole.
One or two spans between dead-end locations should be checked using this method.

3 If the sagging operation takes place from the pulling end back to the payoff end, then the maximum
amount of cable can be recovered.
4 When removing the pulling grip, 3-5 meters of adjacent cable must always be cut-off and discarded.

38
Cable Slack
1 When a splice is completed and fitted into a Joint Enclosure, the cable slack must be coiled into a
glass fibre re-enforced plastic box or onto a slack cross which is mounted to an arm or on the pole.
2 The slack must be coiled before the joint is secured to the pole/arm. Start the slack coiling process
with the joint as the leading end (rolled like a wheel). This will ensure that no twists are imparted to the
cable.
3 On completion of the coiling, place the coil into the slack box or onto the slack cross and secure the
joint closure at a suitable position on the arm/pole.

Damage by veld fire to aerial-cables

1 A fact often overlooked, is that grass or bush under aerial-cable routes create a fire hazard when
dry. Such grass or bush must be cut before it dries during autumn.

39
Cable Hauling
If we can rewind a bit, the advantages of using air-assisted installation techniques over cable hauling
include; longer installation distances possible, less force is exerted on the cable, etc. However and sure
enough, all too often we are still required to haul cable. Strictly speaking, Heavy Duty Duct is the
recommended cable for hauling - specifically designed for long-haul duct applications.
Pre-Installation Check
1 Prior to any hauling, the following must be confirmed:
a. Maximum allowable pulling tension
b. Minimum allowable bending radius during installation
c. Minimum allowable bending radius after installation
d. Cable length
e. Cable length required at the splicing locations

Duct Rodding
1 Rodding is used to clear the duct passage and install the pulling rope, using fiberglass pushrods. An
alternative is to use air-blowing device.
2 a. Push the rod into the duct until the front end of the rod reaches the adjacent HH / MH.
b. Attach the pulling rope to the end of the rod at the adjacent HH / MH.
c. Next, pull the rod and pulling rope back through the duct.
3 If the air pressure method is preferred, the pulling rope will be blown through the duct until it reaches
the adjacent HH / MH.

Duct Testing and Cleaning

1 To clean the duct, attach a cylindrical brush or close-fitting mandrel and a second rope to one end of
the installed pull rope and pull this through the duct.
2 If the cable sample or mandrel cannot pass through the duct, consult with the relevant authority on
whether to switch to an alternative duct or to repair the designated duct.

Centre-Pulls and Back-feeding

One is often more hopeful than optimistic to install a whole drum of cable in one operation, when faced with
hauling a long length of cable. Lubrication helps but more than often, does not completely resolve this
issue. To assist with alleviating this issue, specialized techniques, such as Centre-Pulls and/or Back-
feeding, can be used and applied with either the manual pull or winch methods.
Centre-Pulls
1 Communication, directed by a team leader with team members positioned at each HH / MH is
essential, for that the pulling action to be achieved in a synchronized manner. Communication via the
use of either a walkie-talkie or two-way radio is desirable.

2 In a centre-pull operation, set up the cable reel near the centre of the duct run to be pulled.
3 To avoid cable rubbing against drum flanges keep the drum level - orientate the drum so that natural
payoff direction is towards the pulling direction. Always use cable jacks or a cable trailer to lift the drum
during the hauling process.
4 Align the cable drum so that the cable can be routed from the top of the reel into the duct in as straight
40
 a path as possible.
5 Make use of a flexible cable guide – placed between the HH / MH lid and duct to be used.
6 Ensure that there is a swivel between the cable sock and the hauling rope.
7 Pull the cable in one direction to the intended HH / MH.
8 Uncoil the remaining cable in a figure-eight configuration.
9 Flip-over the figure-eight so that the pulling-eye end of the cable is on top. As mentioned previously,
this can be accomplished by 3-installers, one at each end of the eight, and one at the centre.
10 Pull the exposed end of the cable in the opposite direction to complete the pull. Hand-feeding of the
cable paying off from the figure-eight is required.
10 A warning marker (coloured tape or similar material) may be attached to the pull-line at ± 10m in front
of the pulling grip to alert observers at HHs / MHs that the cable is approaching.
11 Place an end cap on all bare cable ends in HHs / MHs, to prevent moisture and/or dirt intrusion.

Back-feeding
1 In a nutshell, back-feeding is used to provide a series of shorter, lower-tension pulls in one direction –
utilising figure-eighting, where necessary.

Pulling Tension
1 The maximum allowable pulling tension on fibre cable can vary and is dependent on the cable
construction. The maximum tension for a particular cable can be found on the cable spec sheet.
2 Except for short runs or hand-pulls, tension must be monitored.
3 A dynamometer is to be used to monitor tension in the pull-line
4 The use of a breakaway swivel can be used to ensure that the maximum tension of the cable is not
exceeded and should be used as a fail-safe rather than a primary means of monitoring tension.
5 Cable lubricant is recommended for most fibre optic cable pulls as a means of lowering pulling tension.
6 Pulling a new fibre optic cable over an existing one is never recommended due to the possibility of
entanglement.

Pulling Grips
1 Pulling grips provide effective coupling of pulling loads to Kevlar strength members or cable jackets.
2 On cables with no Kevlar strength members, a wire mesh pulling grip and swivel can be used during
cable pulls.
3 A swivel must always be fitted between the hauling rope and cable sock to prevent the cable from
being twisted by the hauling rope.
4 When removing a pulling grip, 3-5 meters of adjacent cable must be cut-off and discarded.

Hauling Rope
1 An 8mm polyester or polyaramid pull rope must to be used for optical fibre cables that are to be pulled
in by hand.
2 When using a hauling winch, a 12,5mm or thicker polyester or polyaramid rope must be used as
hauling rope.
3 Ski-ropes manufactured from nylon are not suitable, as their stretch factor is too high and they can
potentially cut into ducts.
4 Steel hauling rope or galvanised wire must never be used as they can damage ducts and/or cables.

41
Duct Fill Ratios for hauling
1 Fill ratios are calculated by comparing the area of an inner diameter
cross-section of the inner-duct to the outer diameter cross-section area
of the fibre optic cable. For optimum hauling performance, it is
recommended that the cable-to-duct diameter fill ratio does not exceed
65%.

42
 The End

The Fiber Optic Association, Inc.

1-760-451-3655 Email: info@foa.org http://www.foa.org

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