AUDAZ mall- new capital

Technical Submittal For

Earthing Protection Systems

1 30/05/2024 Re-Issued for Approval NOHA MOHAMED YASM

Rev Date Description PREP. CHECK. APPROVED CLIENT

REF.

owner

REF.

MAIN CONTRACTOR GATES CON

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Technical Submittal

To:
Attn: Eng. POLA Date: 30/05/2024

Subject : Technical Submittal for Earthing Protection System

Project : AUDAZ mall- new capital

Dear Sir,

Re, the a/m subject, we are pleased to submit This technical submittal of Earthing system

according to the following:

1. Project Technical specifications.

2. Project BOQ.
3. Local and International codes and standards.

* Manufacture Of Earthing System : FURSE - (UK)

We trust that this Submittal is in full accordance with your requirements.

If you have any queries, please do not hesitate to contact us.

Best Regards

Ibrahim elgaar

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ITEM CONTENTS

1.0 Scope Of Documents 4

2.0 Soil Resistivity 5

2.1 Soil Resistivity Measurements 6

2.2 Soil Resistivity Chart 7

3.0 Earthing System Calculation Sheets 8

Introduction. 9
3.2 Medium voltage Earthing System
3.3 low voltage Earthing System
3.4 low current Earthing System
4.0 Material Lists 15
42 Medium voltage Earthing System
43 low voltage Earthing System
44 low current Earthing System
6.0 Appendices 30

6.1 Appendix A : Earthing System Measuring Procedures. 31

6.2 Appendix B :Soil Resistivity Measuring Procedures. 32

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1.0 Scope Of Documents

The scope of this document is to explain the design and calculation of earthing protection system for audaz mall new capital
1.0

2.0 The design will be in accordance to the international codes & standards involved in these types of systems
Earthing system price in clude cables connection from test link to earth pit
3.0 Grounding electrode shall be 3000mm long, 20mm diameter (3/4") copper clad steel rods

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2. Soil Resistivity Report

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2.1 Soil Resistivity Measurements

The Soil Resistivity Calculated According The Following Formula.

Where ρ = Resistivity in Ohm-m

a = Spacing Between Pin in m

R = Resistance Measurement In Ohm

For More Details About Soil Resistivity Testing Procedure Refer To Appendix B

Site Measurements
Depth(mt)
Point
1 2 3 4 5
R (Ω) 2.12 1.29 1.03 0.36 0.21
Point (A)
ρ (Ω.m) 13.32 16.21 19.42 9.05 6.60

R (Ω) 2.34 1.16 1.17 0.93 0.41

Point (B)
ρ (Ω.m) 14.70 14.58 22.05 23.37 12.88

R (Ω) 3.88 1.47 0.81 0.61 0.47

Point (C)
ρ (Ω.m) 24.38 18.47 15.27 15.33 14.77

R (Ω) 1.92 1.51 0.97 0.32 0.42

Point (D)
ρ (Ω.m) 12.06 18.98 18.28 8.04 13.19

Average ρ (Ω.m) 16.12 17.06 18.76 13.95 11.86

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2.2 Soil Resistivity Chart

RESISTIVITY TEST
Point (A)
Point (B)
30.00 Point (C)
Point (D)
Average
25.00
Resistivity in (ohm.m)

20.00

15.00

10.00

5.00

0.00
1 2 3 4 5
Point (A) 13.32 16.21 19.42 9.05 6.60
Point (B) 14.70 14.58 22.05 23.37 12.88
Point (C) 24.38 18.47 15.27 15.33 14.77
Point (D) 12.06 18.98 18.28 8.04 13.19
Average 16.12 17.06 18.76 13.95 11.86

Electrode Spacing in (m)

Conclusion :
total resistivity at depth4:5 meter average in ohm = 15.54 ohm.meter

So Resisitivity Measured at Grounding Electrode 3.0 m depth = 16.00 Ohm.meter

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3.0 Earthing System

Calculation Sheet

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3.1 Introduction :

A. General

This study is developed for earthing calculations of the earthing system used in this project based on
the international code BS7430:1998 code of practice for earthing).The objective of the
(earthing system is to reduce and control the voltages to an acceptable level for electrical safety for electrical
and non-electrical apparatus to avoid potential danger in case of insulation failures or earth fault

B. Purpose

The purpose of this calculation is:

1.0 To ensure that the requirement of having a maximum value of earthing system resistance to earth
of the electrode system:

2.0 To calculate the earthing conductor cross section used to withstand the maximum short
circuit currents of the electrical network.

C. References

1.0 Code of Practice For Earthing, BS 7430: 1998 Standard

For More Details About Earthing System Measuring Procedures Refer To Appendix A

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1.1 Medium voltage Earthing System

I. System Resistance Calculation is obtained using the following equations as identified by

the BS7430:1998 standard
ρ: Soil resistivity ρ=2 Π R S
R : the resistance to earth of a single rod electrode ( r) in ohms ( Ω ) R = (r / 2 Π Lr ) ( loge (8Lr/d) -1 )
Rn :the combined resistance of rod electrodes in parallel (Rn) in Ohms ( Ω ) Rn =R ( (1+ λa) / n) )
a : Cofficient given by a = (r / 2 Π R S )
2
Rc :The resistance of earthing cable ( Rc) in Ohms ( Ω ) Rc= (r / P Π Lc ) ( loge (2Lc /wh) +Q )
RT :The total reisistance of the system in Ohms ( Ω ) RT < Rn & Rc R T < Rc , Rn

Where :
ρ : is the resistivity of the soil, in ohm metres ( Ω.m )

Lr : is the length of the electrode, in metres

d : is the diameter, in metres (m)

s : is the distance between adjacent rods, in (m)

λ : is a factor given in Table 2 or Table 3; (BS7430:1998 Page 13)

n : is the number of electrodes (as given in Table 2 and Table 3) (BS7430:1998 Page 13)

Lc : is the length of the strip or conductor, in metres (m);

S = .
I . t
k

w : is the diameter of conductor in (m)

h : is the depth of earthing conductor to be buried in (m)

P&Q : are coefficients given in Table 5 for different arrangements of electrode.

II. Input Data

a. As Per Soil Resisistivity Measurements
r = 15.54 Ohm.m at depth of 3.00 mt

For safety and to gurantee specified resistance :

The resistivity shall be r = 16.00 Ohm.m

b. Main parameters

using n= 3 earth pits Lr = 3.00 meter long d= 0.020

S= 6.00 Separted distance h= 0.50 meter in burial depth

λ= 1.66 Lc = 12.00 meter long w= 0.013

P= 2 See table 5 Page 16 BS7430:1998

Q= -1.3

Is.c = 35.00 kA t = 1.00 Sec

K= 254.00 A/mm
2

III. Output Data

R = 5.169 Ω

α 0.082 Ω.m

Rn = 1.958 Ω

RC= 1.991 Ω

RT = 0.99 Ω

Total Earthing Resistance Agree With Technical Specification <2 Ω

S=
2
S= 137.80 mm

bare Cable Cross Section Area Should be 150 mm2

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2.1 Low voltage Earthing System

I. System Resistance Calculation is obtained using the following equations as identified by

the BS7430:1998 standard
ρ: Soil resistivity ρ=2 Π R S
R : the resistance to earth of a single rod electrode ( r) in ohms ( Ω ) R = (r / 2 Π Lr ) ( loge (8Lr/d) -1 )
Rn :the combined resistance of rod electrodes in parallel (Rn) in Ohms ( Ω ) Rn =R ( (1+ λa) / n) )
a : Cofficient given by a = (r / 2 Π R S )
2
Rc :The resistance of earthing cable ( Rc) in Ohms ( Ω ) Rc= (r / P Π Lc ) ( loge (2Lc /wh) +Q )
RT :The total reisistance of the system in Ohms ( Ω ) RT < Rn & Rc R T < Rc , Rn

Where :
ρ : is the resistivity of the soil, in ohm metres ( Ω.m )

Lr : is the length of the electrode, in metres

d : is the diameter, in metres (m)

s : is the distance between adjacent rods, in (m)

λ : is a factor given in Table 2 or Table 3; (BS7430:1998 Page 13)

n : is the number of electrodes (as given in Table 2 and Table 3) (BS7430:1998 Page 13)

Lc : is the length of the strip or conductor, in metres (m);

S = .
I . t
k

w : is the diameter of conductor in (m)

h : is the depth of earthing conductor to be buried in (m)

P&Q : are coefficients given in Table 5 for different arrangements of electrode.

II. Input Data

a. As Per Soil Resisistivity Measurements
r = 15.54 Ohm.m at depth of 3.00 mt

For safety and to gurantee specified resistance :

The resistivity shall be r = 16.00 Ohm.m

b. Main parameters

using n= 3 earth pits Lr = 3.00 meter long d= 0.020

S= 6.00 Separted distance h= 0.50 meter in burial depth

λ= 1.66 Lc = 12.00 meter long w= 0.013

P= 2 See table 5 Page 16 BS7430:1998

Q= -1.3

Is.c = 35.00 kA t = 1.00 Sec

K= 254.00 A/mm
2

III. Output Data

R = 5.169 Ω

α 0.082 Ω.m

Rn = 1.958 Ω

RC= 1.991 Ω

RT = 0.99 Ω

Total Earthing Resistance Agree With Technical Specification <2 Ω

S=
2
S= 137.80 mm

bare Cable Cross Section Area Should be 150 mm2

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3.1 low current Earthing System

I. System Resistance Calculation is obtained using the following equations as identified by

the BS7430:1998 standard
ρ: Soil resistivity ρ=2 Π R S
R : the resistance to earth of a single rod electrode ( r) in ohms ( Ω ) R = (r / 2 Π Lr ) ( loge (8Lr/d) -1 )
Rn :the combined resistance of rod electrodes in parallel (Rn) in Ohms ( Ω ) Rn =R ( (1+ λa) / n) )
a : Cofficient given by a = (r / 2 Π R S )
2
Rc :The resistance of earthing cable ( Rc) in Ohms ( Ω ) Rc= (r / P Π Lc ) ( loge (2Lc /wh) +Q )
RT :The total reisistance of the system in Ohms ( Ω ) RT < Rn & Rc R T < Rc , Rn

Where :
ρ : is the resistivity of the soil, in ohm metres ( Ω.m )

Lr : is the length of the electrode, in metres

d : is the diameter, in metres (m)

s : is the distance between adjacent rods, in (m)

λ : is a factor given in Table 2 or Table 3; (BS7430:1998 Page 13)

n : is the number of electrodes (as given in Table 2 and Table 3) (BS7430:1998 Page 13)

Lc : is the length of the strip or conductor, in metres (m);

S = .
I . t
k

w : is the diameter of conductor in (m)

h : is the depth of earthing conductor to be buried in (m)

P&Q : are coefficients given in Table 5 for different arrangements of electrode.

II. Input Data

a. As Per Soil Resisistivity Measurements
r = 15.54 Ohm.m at depth of 3.00 mt

For safety and to gurantee specified resistance :

The resistivity shall be r = 16.00 Ohm.m

b. Main parameters

using n= 6 earth pits Lr = 3.00 meter long d= 0.020

S= 6.00 Separted distance h= 0.50 meter in burial depth

λ= 1.66 Lc = 25.00 meter long w= 0.006

P= 4 See table 5 Page 16 BS7430:1998

Q= 0.9

Is.c = 12.00 kA t = 1.00 Sec

K= 254.00 A/mm
2

III. Output Data

R = 5.169 Ω

α 0.082 Ω.m

Rn = 0.979 Ω

RC= 0.704 Ω

RT = 0.41 Ω

Total Earthing Resistance Agree With Technical Specification <0.5 Ω

S=
2
S= 28.79 mm

bare Cable Cross Section Area Should be 50 mm2

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4.0 Material Lists

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1.1 Medium volatge Earthing system

` Item Part No Unit Description

1 RB310 Ea Steel Copper bonded earth rod 1.5m X 20 mm

2 CG370 Ea Earth rod coupler
3 ST300 Ea Driving stud
4 CR-2 Ea Cable to Rod ex weld connection
6 PT205 Ea Concerte earth pit " Manufactured by share "
7 LK243-6 Ea Earth bar with disconnecting link
8 local Mt 150mm² Bare copper cable
9 local Mt 120mm² pvc copper cable

2.1 low volatge Earthing system

` Item Part No Unit Description

1 RB310 Ea Steel Copper bonded earth rod 1.5m X 20 mm

2 CG370 Ea Earth rod coupler
3 ST300 Ea Driving stud
4 CR-2 Ea Cable to Rod ex weld connection
6 PT205 Ea Concerte earth pit " Manufactured by share "
7 LK243-6 Ea Earth bar with disconnecting link
8 local Mt 150mm² Bare copper cable
9 local Mt 120mm² pvc copper cable
3.1 low volatge Earthing system
` Item Part No Unit Description

1 RB310 Ea Steel Copper bonded earth rod 1.5m X 20 mm

2 CG370 Ea Earth rod coupler
3 ST300 Ea Driving stud
4 CR-2 Ea Cable to Rod ex weld connection
6 PT205 Ea Concerte earth pit " Manufactured by share "
7 LK243-6 Ea Earth bar with disconnecting link
8 local Mt 50mm² Bare copper cable
9 local Mt 35mm² pvc copper cable
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6.0 Appendices

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6.1 Appendix A

6.1.1 Earthing System Measuring Procedures

Fall of Potential method

1.0 Only disconnect one earth electrode at a time for testing. If only one earth electrode exists then the
installation MUST be disconnected from all sources of mains power (including generators).

2.0 Before the earth electrode is disconnected for testing. It is not sufficient to remove the mains earth bond
for this test as other connections between the lightning protection system and mains earth will probably exist.

3.0 On completion of the installation or any modification to it, the following measurements and/or checks
should be made and the results recorded in an earthing system logbook.

4.0 The resistance to earth of the earth termination network and of each earth electrode.

5.0 The results of a visual check on all conductors, bonds and joints or their measured electrical continuity.

6.0 Tests should be repeated at fixed intervals, preferably not exceeding 12 months.

7.0 Testing earth electrode resistance.

8.0 The resistance of each earth electrode should be measured with that electrode disconnected from the
rest of the system and the results recorded. The preferred method of measurement is illustrated in Figure2.

9.0 This test is known as the "Fall of Potential" method.

A known current is passed between the earth electrode (E) under test and the test electrode (C).
The voltage between E and a second test electrode (P) is measured. From these values the earth
electrode resistance can be calculated. Measuring instruments combine the above functions and indicate
earth electrode resistance directly.

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6.2 Appendix B

6.2.1 Soil Resistivity Testing Procedure

A. Introduction

This document is a guideline for testing and determination of the soil resistivity, It presents
the theory and methodology of soil resistivity testing, the equipment requires, a detailed test procedure and forms.

It also explains the use of the soil resistivity data in designing grounding system to meet the specifications
of the project.

B. Purpose

Soil resistivity data is the key factor in designing a grounding system for a specific performance objective.
All soils conduct electrical current, with some soils having good electrical conductivity while majority has
poor electrical conductivity.

The resistivity of soil varies widely throughout the world and changes dramatically within small areas.
Soil resistivity is mainly influenced by the type of soil (clay, shale, etc.), moisture content the amount of
electrolytes (minerals and dissolved salts) and finally temperature.

When designing a grounding system for a specific performance objective, it is necessary to accurately
measure the soil resistivity of the site where the ground to be installed .Grounding system design is
and engineering process that removes the guesswork and “art "out of grounding . It allows grounding to be
done “right" the first time.The result is a cost saving by avoiding change orders and ground enhancements.

C. Method
`
The best method for testing soil resistivity is the Wenner Four Point method. It uses a 4-pole digital
ground resistance meter, such as the Megger 5/4., probes and conductors.

It requires inserting 4 probes into the test area. The probes are installed in a straight line and equally spaced
The probes establish an electrical contact with the earth. The four pole test meter injects a constant current
through the ground via the tester and the outer 2 probes.

The current flowing through the earth (a resistive material) develops a voltage / a potential difference.
This voltage drop resulting from the current flow is then measured between inner probes.

The meter then knows the amount of current that is flowing through the earth and the voltage drop across
the two center probes. With this information the meter uses Ohms law(R = E/I) to calculate the resistance in Ohms.

Soil resistivity is then calculated in Ohms-meter which is the resistance of a volume of earth that is 1 meter
by one meter or one cubic meter.

To convert from the displayed ohms to ohms-meter resistivity is calculated according the following formula.

ρ ( ohms-meter) = 2.π.R.a

Where:

a = Distance between electrodes in meters.

R = the resistance in Ohms measured between the middle electrodes, i.e. the reading obtained from the meter.

ρ = Apparent Resistivity.

P.S. (Some Soil resistivity measuring equipment gives a direct reading for the ρ).

Readings are usually taken at probes spacing’s of 1, 2, 3, 4, 5 meters.

If the testing is being performed for the purposes of ground potential rise ( GPR) studies ,or for substation
design , readings up to 50 meters probe spacing should be performed.

The calculated soil resistivity is the average of soil resistivity from the surface to depth equivalent to the
probe spacing. For example, a probe spacing of 5 meters spacing between each probe will provide the a
verage soil resistivity between the surface and a depth of 5 meters.

Several readings at the different probe spacing and at different areas of the site are required.

C. Soil Resistivity Testing Procedure

1. Equipment Required :

• A 4- Pole Digital- Ground Resistance Tester.

• At Least four probes.
• Four insulated wire conductors.
• Measuring tape.
• Hammer (to drive probes).
• User's Manual for Meter.

2. Procedure :

The Following Procedure is generic and will work with all meters.

Step 1. Verify that meter strip between the meter's C1 and P1 terminals are disconnected.

Step 2. Install the 4 test probes in the ground equally spaced in a straight line.

Step 3. Using the conductors, connect the C1, P1, P2, and C2 terminals to the probes The electrodes
must be connected in order from the end, to the C1, P1, P2 and C2 terminals. The test results
will be invalid if the probes are not connected properly. .

Step 4. Press the test button and read the meter reading Then record the reading in the test report .

Step 5. Steps 1-4 of this procedure must be repeated at multiple locations On the site to obtain a reliable
soil profile

Step 6. Calculate soil resistivity using the formula described earlier Measurements should be taken
along 3-directions at each site as a minimum..

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