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What is Conduit Wiring? Types, Advantages & Applications

Engr Fahad 31,399

Table of Contents

Introduction

Wiring Systems

Conduit Wiring System

Types of Conduit Wiring

Types of Conduit

Conduit Size

Types and Number of Wires Used in Conduit

Precautions in Surface Conduit Wiring

Advantages

Disadvantages

Precautions in Concealed Conduit Wiring

Advantages of Concealed wiring

Disadvantages of Concealed wiring

Uses of Conduit Wiring

Introduction

Installation means the act of installing something. Connecting two things or recombining two things in
such a specific configuration or sequence that a complete system builds as a result of their joining or
conjugation, is called installation. Electrical installation means the provision of corresponding supply to
electrical appliances or instruments and their induction together with the safety circuits. The electrical
installation provides a safe source for connecting electrical appliances of a consumer with electrical
supply through over current and earth leakage protection. It consists of all cables, pertinent safety
components, and control gear. In short, fixing different types of circuits and electrical equipment on a
panel, recombination of electrical components with an incomplete system for making a complete
system thereof, installation of electrical wiring in a precise or correct fashion either temporarily or
permanently, installation of protective gadgets, installation of service lines on a one floor or multi-floor
buildings, installation of motors, installation of load and earthing system are all included in electrical
installation. In fact, the electrical installation consists of a complete system of all types of electrical
wiring and its associated electrical components or instruments, protection, testing, signal
communication circuits, and entire instruments related to the electrical control, installed in residential
and commercial buildings, industrial units, factories, and refineries, etc.

allpcb circuit

Wiring Systems

The following wiring systems or methods are used:

Cleat Wiring System

Batten Wiring System

Casing Capping Wiring System

Conduit Wiring System

Conduit wiring may further be classified into the following two types
(i). Surface Conduit Wiring

(ii). Concealed Conduit wiring

Conduit Wiring System

The system of wiring in which all wires or cables from supply to load are passed through iron or PVC
pipes is called a conduit wiring system. The objective behind passing wires through the pipes is to
safeguard it against unpleasant consequences of weather conditions, physical breakdown, fire dangers,
and atmospheric effects. It has to be kept in mind while passing cables through the pipes that that its
insulation does not get damaged. This type of wiring system is most widely used as compared to the rest
of the wiring systems.

Types of Conduit Wiring

Surface Conduit Wiring

Concealed Conduit Wiring

Surface Conduit Wiring

If conduits are installed on the surface of a roof or wall, it is called conduit wiring. For this type of wiring,
the first holes are made on the wall surface in a straight line at equal distances. Then rowel plugs are
fixed into these holes and saddles are installed above these rowel plugs through screws. After this,
conduits are installed above it. The size of the conduit used in this type of wiring depends on the
number of wires going to be passed through it. Moreover, the size of conduit which is used in wiring,
and fittings will also be used of the same size.

In figure 1.7,
Conduit Wiring

has been illustrated. This type of wiring is done away from gas, water, and steam pipes. This type of
wiring is extremely suitable for houses, factories, and industries.

Concealed Conduit Wiring

If PVC conduit is concealed by means of carving grooves on the wall, and then plaster is done above it,
this type of wiring is called concealed conduit wiring. As this type of wiring is not visible from outside,
only switches and lamp holders are visible, therefore it is known as concealed conduit wiring. In other
words, wiring carried out inside a pipe within a wall is called concealed wiring. In the concealed type
wiring, grooves are formed on the wall, pipe fitted in it, and then covered with plaster. Only junction box
spots remain visible, wherefrom wiring can be looked after and repaired. Conduit pipes are tightly fixed
onto the walls through hooks prior to being plastid. Prior to putting concrete on a roof during a linter,
PVC conduit pipes are spread all over the roof, whereas prior to doing plaster on the building walls,
grooves are dug onto the walls, and then conduit pipes are fixed in these grooves. It is then plastid. After
the plaster has been completed on roofs and walls, wires are inserted into these fitted conduits with the
help of steel wires. As conduits are not visible in this type of wiring, therefore it remains protected
against fire, water, moisture, and other weather conditions. In the concealed wiring system, all
switchboards are also fitted on walls and flush-type switches and sockets are used in this type of wiring.
This type of wiring is commonly used in houses, offices, bungalows, and all other modern buildings, etc.

Types of Conduit

The following two types of conduits are used in the conduit wiring system according to their structure.

(1). Metallic Conduit

(2). Non- Metallic Conduit

Metallic Conduit

Metal conduits or pipes are fabricated from steel. These conduits are durable and also costly. Therefore,
these are used only in high–standard construction. Technically, a number of merits have been observed
in steel conduits e.g., at the time of fixing a conduit if there is a need to bend it, it can easily be done
without any sort of breaking or rupture in pipes. Further, no cracks or hiatus occur in it. There are two
types of metal conduit with respect to gauge.

(i). Light Steel Sheet Conduit (Class A Conduit) or Low Gauge Conduit

(ii). Heavy Steel Sheet Conduit (Class B Conduit) or Heavy Gauge Conduit

(i). Light Gauge Steel Conduit (Class A Conduit)

Light steel sheets or class A conduits are such steel pipes that have no grooves or narrow stripes on
them (i.e., they can be used without forming any kind of grooves or stripes). Therefore, their knots or
joints are closer or adjacent which can be fortified through welding or breezing. As such pipes are
manufactured from light steel, therefore such pipes cannot be twisted or bent extensively. These types
of pipes are relatively cheaper compared to heavy gauge steel pipes. These are available in a diameter of
13 millimeters to 50 millimeters and they can be applied in mediocre-type buildings for a 250 volts
supply. Light-sheet quality conduits are never used in power wiring.

(ii). Heavy Gauge Steel Conduit (Class B Conduit)

The heavy-gauge steel conduit (class B conduit) is uniformly designed with a neat and clean interior
structure. Thus, the danger of wires cutting or erosion does not exist at the time of inserting wires into
the pipes. The heavy gauge conduit cannot be used without making narrow strips or grooves on it and
all joints are stiffened by means of tightening narrow strips at the ends of pipes. As a result of combining
together through narrow strips, the electric continuation of such pipes remains stable. (Remember that
if wires insulation gets damaged or weakens due to any reason, the flow of leakage current continues
within the steel pipes and an electric shock can be felt by touching any part of switchboards or pipes. In
order to eliminate this danger, entire conduit wiring and annexed accessories are properly connected
together and earthed on two spots, so that leakage current shifts to earth and no electric shock can be
felt upon touching it). In order to use these conduits within a wall a blackish color, for use on surfaces
inside the room a black color, and for exterior use, galvanizing is done. In size, these conduits are
available up to 63 mm in diameter. The heavy gauge conduits can protect wires in a better manner. They
can be bent or turned at any angle without any danger of breaking down or bursting. Wires can easily be
injected into it without any sort of damage to the wires. They view quite seemly to eyes. They have no
danger of being by fire etc. They are durable and robustly built, as a result, they can easily sustain any
sort of jerks, etc. They also do not have any sort of weather impacts on them; therefore, such pipes are
vastly used in top–quality construction. However, they have just one defect i.e. they are costly.

Non–Metallic Conduit

PVC conduits are abundantly used nowadays as a non–metallic conduits, because PVC pipes are quite
flexible, and they can be twisted or bent quite easily. A hard PVC pipe can be bent according to ones’
needs by means of providing heat to it through fire. The sizes of PVC pipes are also similar to metallic
pipes and these pipes are available in coils. Whereas the length of every pipe ranges from 3 meters to 10
feet. As non–metallic pipes are being fabricated from insulator material, therefore the biggest issue in it
is the electric continuity of the earth. That’s why they are not earthed. As such, a separate earth system
has to be devised for the purpose. Heavy gauge pipes are prepared in PVC form also, which are used in
places where the probability of external pressure or concussion on wiring exists. As PVC pipes pose
considerable resistance against acidic vapors and moisture etc., therefore it is commonly used for a
single-phase system.

Conduit Size

Normally, pipes are available for conduit wiring in 13, 16.2, 18.75, 20, 25-, 37-, 50- and 63-mm diameter
(or ½, 5/8, ¾, 1, 1.25, 1.5, 2 and 2.5 inches)
Types and Number of Wires Used in Conduit

Mostly VRI and PVC wires are used as conduit wiring, which is suitable for low and medium voltage
grades. Where ever the risks of moisture, humidity, external shocks, and contusion are high, tough
rubber sheathed PVC wires are used. Flexible wires should not be used in conduits, because the risk of
damage to their insulation or even breaking down of insulation exists at the time of putting wires into
the conduits.

As the maximum number of wires which can be adjusted in a conduit depends on conduit size, wires
sizes, wires insulation, wires’ current capacity, weather conditions, etc., therefore cables manufacturing
companies issue tables regarding the number of wires to be injected into a conduit. It should be bear in
mind while inserting wires into a conduit that wires could be pulled easily in the conduit. And at the
same time, they could be moved easily when there is a need to repair it. Remember that the collective
size of wires to be inserted into pipes should not exceed 40% of the interior pipe size. In table 1.1, the
number of cables in a specific type of conduit has been reflected according to the cable sizes.

Table 1.1 – the number of cables in a conduit

Number of Cables in a Conduit Cable Size

25 cm (1”) 20 cm (3/4”) 15 cm (3/8”) Decimal System English System

16 10 6 1 / 1.13 1 / .044

13 8 5 3 / 1.38 3 / .029

10 6 4 3 / 1.78 3 / .036

10 6 4 7 / 0.85 7 / .029

7 4 3 7 / 1.00 7 / .036

5 3 2 7 / 1.04 7 / .044
Conduit Fitting

In a conduit wiring system, different types of accessories or materials are used for the purpose of joining
pipes, which are known as fittings. For example, elbow, junction box, union, socket, nipple, cross joint
junction, clip, saddle, grips, inspection band, inspection T, etc. Bending of a conduit when required, is
also included in it.

There are two types of conduit fitting. Surface and concealed. Surface fitting is done for the purpose of
wiring which is mostly carried out in factories, workshops, go-downs, hospitals, and other commercial
organizations. Its advantage is that wiring can be inspected as and when required. On the contrary,
concealed fitting is used for concealed wiring, which is mostly carried out in homes, offices, shops, hotels
etc. As conduit is installed in a concealed manner in this type of wiring, therefore this type of wiring
normally presents a very beautiful appearance. However, its inspection is relatively difficult whenever
required.

Conduit Fixings

The accessories which are utilized in order to tightly install a surface conduit on walls are called conduit
fixings. For this purpose, different types of clips and saddles are used. The distance of saddle with the
conduit is retained at approx. 3 feet and, in every fitting, their distance is maintained 4 inches. Saddles
are installed on rowel plugs or wooden dowel pins with the help of rust-free round-headed screws.
Saddles can be found in different sizes and shapes according to needs e.g., spacer bar saddle, distance
saddle, multiple saddle and girder clip, etc.

Precautions in Surface Conduit Wiring

Conduit should be selected according to the number of wires and sizes in such a way that a reasonable
space is available after inserting the wires.

Conduit fittings must always be installed on walls according to conduits weight

Rowel plugs or dowel pins are planted at a reasonable distance according to the sizes and weight of
pipes

An earth wire of an appropriate size should also be run along pipes and it should be earthed at
reasonable distances by combining with conduits. Moreover, all junction boxes, iron-clad switches, and
distribution boards, etc. should also be properly earthed.
Conduits should be kept apart from water and gas pipes

Wires should not be penetrated through the conduit in excess of the required numbers

Wires of opposite polarity must essentially be passed through metal pipes so that a substantial voltage
drop does not occur as a result of AD current

Pipes should reach inside up to the metal boards and bushes should be installed on their heads or ends

PVC pipes must not be used in places where the danger of mechanical disruption or wear and tear
persists

After grafting grooves or narrow strips on metal pipes, its edges should adequately be smoothened
through a sandpaper

A separate saddle and clamp should be used for each pipe and if most of the conduits are in parallel,
multiple saddles should be used for the purpose. Only one saddle should never be used for all pipes,

All bends on pipes should be in a rounded form so that wires insulation is not scratched at the time of
dragging wires

The number of 90-degree bends between adjacent boxes should not exceed 4

At the time of bending a conduit, it should be filled with sand, due to which, it does not skid from the
twisted spot

Metal conduit should be bent by means of heating it through a yellow lamp

Only girder clamps should be applied while fixing conduits along guarders and beams

At the time of dragging wires into conduits, it must be ensured that no twists or winds occur in wires
and wires should be drawn perfectly straight.

An inspection T and bend and box should be used in a long conduit

Conduits less than 16 mm in size should never be used

Conduit pipes should internally be clean and dry and externally should be painted in order to get
protected from rust. They should always be installed through a heavy gauge saddle
Advantages

Surface wiring has under – mentioned advantages;

Alterations or additions are possible in this system according to future needs

Its revamping, repairing, and maintenance is quite easy

In case wiring is performed in an expert manner, it seems relatively good-looking

In the case of PVC conduit, this wiring remains protected from rust as well as fire

This type of wiring can also be used in places prone to weather as well as chemical impacts

As a result of proper earthing of metal conduit, no danger of an electric shock exists in this type of wiring

It has a long life

It is a reliable and popular method for wiring purposes

Most of the accessories used in this type of wiring, can be reused as required

Disadvantages

It tends to be less attractive as compared to the concealed wiring

It requires significant labor and skilled technicians

As dust and cobwebs etc. form on conduit, therefore they require occasional cleaning or dusting

They are not protected against mechanical shocks and as a result of such blows, there always remains a
risk of conduit getting uprooted

If earthing has not properly been done, then in the case of metal conduit, the risk of an electric shock
lingers on

A significant amount of time is required for the purpose of installing this type of wiring

It is comparatively expensive due to the large application of accessories e.g., elbows and Ts, etc.

It is difficult to trace out fault and repair it quickly. Repair work involves a lot of time-consuming

If a metal conduit has been used in wiring, it becomes imperative to get it earthed, which obviously
involves extra costs

During the wiring process, the straightness of the conduit is always kept in mind for beautification
purposes
Precautions in Concealed Conduit Wiring

The precautionary measures being employed for concealed conduit wiring are nearly similar to those
being adopted for surface wiring, however following some precautions are specifically associated with
concealed wiring, which must necessarily be kept into mind;

On a concrete roof, conduit must be spread before the roof is being concreted

At the time of putting conduits on a concrete roof, pipes of different points should be combined directly,
and bends should be avoided as far as possible.

Mouths of conduits should properly be covered with some paper, so that cement does not freeze on it
during plaster

Pipe must essentially end up within the box

Every metal box must duly be earthed

Wires should be passed through conduits prior to fittings

For making connections in a concealed wiring, the looping in the method should be adopted (i.e., every
wire which reaches a certain point may be joined with that point and then without cutting, bend it
towards another point). Though more wire is consumed under this method, however wires are neither
cut nor any kind of bend is put on them.

As moisture infiltrates into pipes during watering of the plaster, therefore a cotton cloth must be passed
through the pipes prior to the inserting of wires into the pipes, so as to clean up the moisture

Metal conduits being used on walls and ceilings must properly be painted so as to protect them against
rust etc.

It is common that junction boxes to move down from the wall surface as a result of plaster. For this
purpose, a special type of paint must be used in order to bring the junction box’s surface equal to the
wall surface, so that wiring does not seem obnoxious.

All boxes should vertically and horizontally be absolutely straight. In the case of the crooked or curved
boxes, wiring presents an unpleasant look

If metal conduits have not been used for installing wires on an iron box, then the box should be earthed
separately

For the purpose of installing metal pipes on a metal junction box, only an even and smooth brass bush
should be used.
While passing wires through a conduit, wires must be dragged in such a fashion that their insulation
does not damage

A wooden ladder should be used instead of an iron staircase while doing electric work

A protective glass or spectacle must be used while grafting a groove, so that cement or sand particles do
not enter the eyes

At the time of dragging wires into the conduit, wires reels or drums must rotate freely so that wires
could enter into pipes perfectly straight.

The number of cables going to be passed through a conduit should be such that enough space or
capacity remains available even after the existence of these wires.

Advantages of Concealed wiring

This wiring seems pretty attractive due to the fact that the conduit is buried with the walls.

It is protected against all sorts of weather as well as chemical effects

It is quite enduring as a result of being protected against mechanical shocks

It remains protected against fire eruption

As the straightness of wiring is not cared about in this type of wiring, therefore the usage of elbows and
Ts, etc., is relatively less. As such, it is less time consuming and also less costly

There is no danger of conduits getting uprooted

It is one of the safest wiring systems

It is most popular as well as reliable as compared to the rest of the wiring methods

There is no menace of electric shocks or accidents

There is no need to earth it due to the application of PVC pipe.

Disadvantages of Concealed wiring

Once the wiring has been completed, additions or alterations in wiring become difficult

It is more costly as compared to other types of wiring

It is difficult to find out the defect and remove it

As a result of making grooves in the wall, there is an imminent danger of the building getting unstable
and weak

Extra hard work is required for making grooves apart from being time-consuming

Uses of Conduit Wiring

As a result of being protected against setting on fire, getting rusty, safeguarded against mechanical
shocks, free from chemical and weather conditions, being beautiful, enduring, and safest, the conduit
wiring system is the only wiring system, which is being considered the most popular despite being
expensive and it is widely used in the following places;

(i). Places where extreme dirt and dust exist or where cotton wool work is performed e.g., textile mills,
sawmills, flour mills, etc.

(ii). Places and areas having moisture e.g., cold storage, etc.

(iii). Workshops etc.

(iv). All such places, where the danger of fire breaking persists e.g., oil mills, varnish factories,
ammunition companies, etc.

(v). Places where important documents are preserved e.g., record rooms, courts, etc.

(vi). Ordinary residential and public buildings, where beautification is given foremost attention

(vii). In large houses, bungalows, commercial buildings, offices, etc.

(viii). In cinema houses, railway stations and hospitals, etc.

(ix). Parks, recreation spots, where safety is being given paramount importance

(x). In mosques and other places of worship e.g., churches, synagogues, temples, etc. due to their
attractiveness and durability

NexWhat is an Electric Cable?An Eclectic cable is a cable used to distribute and transmit electrical
power. The Electric Cable is used to transmit high voltage where overhead lines are impractical to
use.An electric cable is made of three kinds of things those are – ConductorDielectricSheathThe
conductor provides the conducting path in the Electric Cable. The insulation or dielectric withstands the
service voltage and isolates the live conductor with another subject.The sheath protects the Cable from
all external influences like chemical and fire attacks. Also, it prevents moisture from harming the electric
Cable.IntroductionElectric cables are usually made of copper Because electricity moves well in copper.
Copper is not as expensive as silver, making the work easier. Sometimes aluminum is used in cable
making because it is cheaper than copper. A cable is made when many wires come together.Electrical
cables are shielded conducting wires, used in the generation, transmission, and distribution of electrical
power. Electrical cables, in a circuit, are joined through connectors. A combination of cables and
connectors is known as a cable assembly. The conducting wire in a cable carries electricity whereas the
insulator and the sheath give protection to the cables from unintended circuit paths and chemical
reactions. Cables can be classified into various categories, depending on their different uses and
structures. Some types are coaxial cables, twisted pairs, optical fibers, patch cables, power cables, data
cables, etc. Components of a CableA cable should have the following three components,Conductor: The
conducting part is used to transmit electricity. Extensively used conductors are copper and
aluminum. Insulator: To keep the conductors separated from each other and prevent unintended paths
for current flow (e.g. short circuit), the wires are shielded with insulating materials. Various synthetic
polymers are used for this purpose.Sheath: It is yet another layer to give protection to the wires from
chemical reactions with the atmosphere. A common material for the sheath is PVC (polyvinyl
chloride).Classification of Cables and ColorsDifferent colors of wires are used for different purposes. In
DC circuits, the colors are,Red: Wires for positive current.Black: Wires for the negative current. White or
Grey: Ground wires.(Image will be Uploaded soon)For AC circuits (power 120/208/240 Volts),Black:
Phase 1 lines are colored black. These wires are for power generation.