MST-EL-04 Installation of Earthing System

ABU DHABI FUTURE SCHOOL PROGRAM – Phase (2)PACKAGE – 4

KG SCHOOLS AT Al BAHYA & AL FALAH

Method Statement for Installation & Testing of Earthing System

ClientAbu Dhabi Education Council

EmployerMusanada

ConsultantDewan

ContractorUnited Engineering Construction

MEP SubcontractorAl Sabbah Electromechanical

Issued on 02 April, 2013

Prepared By: Reviewed by Approved by MSRev. Name Date Name Date Name Date No.

0ASEM-MST-EL-04


TABLE OF CONTENTS

1. Purpose2. Scope3. Legislation and Code of Practice4. Reference5. Definitions6. Resources6.1. Equipment6.2. Safety of Equipment’s7. Safety Precautions7.1. Construction Hazards7.2. Personal Protective Equipment7.3. Safety Training and Emergency procedures7.4. First Aid8.Detailed Construction Sequence (Methodology)8.1. Procedure9.Construction Program9.1 Housekeeping 9.2 Protection of Executed Works 9.3 Responsibilities 9.4 Records10.Inspection and Testing11.Related Forms12.Attachments

ASEM-MST-EL-04 Rev.0 Page 2 of 10


1. Purpose

This document describes the methodology of installation & testing of earthing system for Abu Dhabi Future School Program – Phase 2, Package 4 Project, and to ensure that all concerned persons are familiar with the sequence of activities, utilization of resources, and execution of the works in compliance with applicable Safety and Quality Procedures, and Project Documents and Specification.

2. Scope of WorksThis method statement is intended to outline the activities and the methods used for the installation & testing of earthing system. All activities will be carried out in accordance with the contract details and in full compliance to the Contract Specifications and documents. All work within the rights-of-way of the standards and specifications will be done in compliance with requirements issued by authorities.

3. Legislation and Code of Practice

All related codes and standards referenced in the project electrical specifications volume 3 part F division 26, section 26 05 26.

4. Reference Contract Specifications Approved Drawings

5. DefinitionsClient : Abu Dhabi Education CouncilConsultants : DewanContractor : United Engineering Construction

6. Resources

6.1. Equipment / Tools

NO. DESCRIPTION

1 Measuring tape

2 Meggar for earth testing

3 Spanners

4 Hammer

5 Screw driver

6 Exothermic welding tool kit

6.2 Safety of Equipment’sNecessary measures will be taken for the safety of the equipment and any other works affected by the works subject of this document. Relevant entities which might require protection include any such works in the vicinity of the area of work or on the service access or discharge path.

The construction team will ensure that any such requirements are documented.



7. Health, Safety & the Environment

7.1 Construction Hazards (tick as appropriate)

Corrosive Oxidizing Highly flammable

Extremely flammable Toxic Highly Toxic Irritating Harmful

Explosive Danger for the Environment

Constrained Space

Slippery Surface

Danger of Electrocution

Falling from Height Other

____________________

____________________

____________________

____________________

The hazards identified above will be controlled under the overall Project Safety Plan which is a separate document communicated to all parties on the project.

7.2. Personal Protective Equipment (tick as appropriate)

The works subject of this document requires that the following PPE be used:

Safety Precaution Helmet Hi-Viz Eye

ProtectionFace

ProtectionMask

RequiredRespirator Required

Ear Protection

Gloves Required

Safety Shoes Required

Protective Clothing

Safety Harness

Equipment Guards Lifejacket Other

____________________

____________________

____________________

____________________

7.3. Safety Training and Emergency proceduresBefore commencing any works, all employees will attend a site safety induction training to ensure all safety measures are understood and implemented and to cover specific procedures in case of emergency. If necessary, practical training exercises will be conducted on escape routes, signage, evacuation and rescue.

7.4. First AidPrior to the commencement of work, arrangements will be made for medical facilities and medical personnel to be available from prompt attention to the injured person. The contractor’s vehicle assigned to the job site will be used for transporting the injured person to the first aid station and to the nearest hospital when required.



Name of On-Site First Aider/s:

First Aid Box Location:

Location of Nearest Hospital:

First Aid and Medical Supplies available at site:

Potable Water Ice Cubes

10x6cm Sterile Gauze Pad 4x6cm Gauze Roller Bandage

10x10cm Sterile Gauze Pad 8x10cm Gauze Roller Bandage

Large Sterile Gauze Pad 10x12cm Gauze Roller Bandage

Burn Dressings 5cm Elastic Bandage

7.5cm Elastic Bandage 10cm Elastic Bandage

Triangular Bandage Barrier Device for CPR

Adhesive Skin Tape Adhesive Leucoplast Tape

Emergency Blanket Safety Pins

First Aid Scissors Tweezers

Disposable Gloves Instant Cold PackNon-prescription Medicines (Aspirin, Ibuprofen, Acetaminophen) First Aid and Burn Spray, Deep Heat Spray

8. Detailed Construction Sequence (Methodology)

8.1 Technical Requirementsa. The complete installation covered by this specification shall be efficiently bonded back to the main

switchboards through the metal sheathing of cables, the steel conduit, the trunking system and earth wires/bars.

b. The nominal cross-sectional area of all earth continuity conductors shall be in accordance with the IEE and ADDC regulations. The earth wire size shall be equal to the phase wire if the conductor cross section is less than 16 square millimeter and shall have half of the phase conductor size for sizes higher than 16 square millimeter.

c. A 150mm² earth bar riser shall be installed in each electrical room and shall be connected to a 6mm x 50mm x length (as shown on the plan). Earth bar with enough number of ways and mounted on high impact uPVC channel with disconnecting link provided in each electrical room and shall be connected to the individual switchboard earth bar through a cable sized in accordance to IEE Regulations and to the equipotential bonding conductor connecting metal conduits, trunking systems, metal frames, enclosures, cable sheaths, A/C duct work, pipe riser etc.

d. All switchboards, metal conduit and trunking systems, metal frames, enclosures, lighting fittings and cables sheaths shall be bonded together and connected through 16mm2 PVC cable to the earth bar of the appropriate switchboard. Similarly all earth pins and metallic plates of socket outlets, switches, accessories and enclosures shall be bonded to earth with earth continuity conductors. Each individual earth path shall be electrically continuous throughout its length from the farthest point of the associated part of the system back to the main earth.

e. Where separate pieces of apparatus connected to different phase are, of necessity erected or positioned less than two meters apart, an equipotential bonding conductor of single core 70mm2 PVC sheathed shall be installed between such pieces of apparatus.

f. In the substations, earth grid bus shall be provided and shall connect all the electrical equipment to the earth pit.



g. The star point of the transformers and generators shall be solidly earthed through separate earth well.h. All earthing cables shall be installed in accordance with the relevant requirements called for in the cables

section of this specification.i. All wires and cables shall be protected against mechanical stress and corrosion. All joints between wires and

earthing metal work shall be mechanically sound and bimetallic connector shall be used wherever necessary.j. 2.2.10 All bonding leads shall be carried out using threaded fittings, lockout/hardware, thermite welding or any

other method approved by THE CONSULTANT.k. A test connection link shall be provided for testing purpose.

Earth wellEarth wells shall be provided only to provide the earth grid at the service block and at substations. Earth well with 100mm diameter GS pipe shall be driven up to the water table. An earth bar shall be welded to the top of the earth well for branch connections. The well shall be protected by a concrete housing with MS or concrete cover of 250mm x 250mm x 10mm at grade level.

Earth pits20mm diameter copper earth rod shall be driven to a minimum depth of 6M and an earth bar shall be provided to the top of the earth pit for branch connections. Earth pit shall be protected by concrete housing and MS or concrete cover at grade level. Bentonite shall be provided in the pit around the earth rod. The number /depth of pits shall be sufficient to make the system resistance less than one ohm. Earth cables shall be buried at a minimum depth of 500mm after coordinating the same with other services.

8.2 Installation Procedurea. Ensure that approved installation detail drawings are available, material is available onsite and approved after

inspection from consultant.

b. Predetermined points will be identified from the drawings.

c. Earth spikes will be inserted in to predrilled holes checked and back filled with Copper cable/tape to be run out

into raft.

d. Earth spikes to be connected to copper cable/tape by clamps.

e. Provide complete installations to earth every source of energy and to provide protective earthing and

equipotential bonding, based on the TT system arrangement( including Transformer neutral earthing, Main

earthing terminals or bars, Exposed conductive parts of electrical equipment, Extraneous conductive parts &

Standby generator neutral earthing.)

f. Earth Rods: While fixing earth rods, ensure that resistance areas associated with individual rods do not

overlap. Earth rods are to be located at a distance greater than 600 mm from foundations of bbuildings.

g. Where rock is encountered, a hole of sufficient size is to be drilled before lowering the rod. Conductive filler

such as Marconite or Bentonite or equal filler that will not corrode is to be provided around the rod.

h. Buried earthing conductors are to be laid at a depth not less than 0.8 m from ground surface.

i. Earthing conductors are to follow shortest path between earth rods and main earthing terminals or bars, and

are to run in PVC conduit (duct) fastened to building structure by approved supports and extending 0.2 m

above level, and are to be protected against mechanical damage and corrosion.

j. Protective Conductors: Separate protective conductors, which are not part of a cable, are to be fixed on same

support or drawn into same conduit as circuit conductors.



k. Protective Bonding: Remove any non-conductive paint, enamel or similar coating at threads, contact points

and surfaces and ensure that bonding is made by fittings designed to make secure bonds.

l. The whole of the earthing and bonding shall be installed and tested as specified, in accordance with the

requirements of the IEE Wiring Regulations, as per ADDC/AADC requirements and to CONSULTANT approval.

m. All enclosures, equipment, exposed conductive parts, extraneous conductive parts, metallic trunking, metallic

conduits, metallic cable trays and other metalwork, other than any live part, forming protection to or part of

the electrical installation, including apparatus and appliances, shall be effectively bonded to earth.

n. Remove non-conductive coatings from threads or other contact surfaces to ensure good electrical continuity.

o. Protect all exposed grounding conductors from mechanical damage.

p. All joints shall be of thermo-weld and soldered joints are not permitted.

q. All metal poles supporting outdoor lighting fixtures shall be earthed using earth rod and earth pit.

r. Drive earth rods until tops are 50mm below finished floor or final grade, except as otherwise indicated and

interconnect with earthing electrode conductors without damaging copper coating. Route the earthing

conductors along the shortest and straight paths possible, avoiding obstructing access or placing conductors

where they may be subjected to strain, impact or damage.

s. Lay the underground earthing conductors at least 500 mm below grade.

t. Provide insulated copper earthing conductors in conduit from building’s main earthing bus to main metal

water service entrances to building and connect to the water service pipes by earthing clamp connectors. Do

not install an earthing jumper across dielectric fittings.

u. Bond interior metal piping systems and metal air ducts to equipment earthing conductors of associated

pumps, fans, blowers, electric heaters, etc. Use braided type bonding straps.

8.3 Connections

a. Make connections such that possibility of galvanic action or electrolysis is minimized. Connectors, connection

hardware, conductors and connection methods shall be selected such that metals in direct contact will be

galvanically compatible. Use electroplated or hot tin coated materials to assure high conductivity and to make

contact points closer in order of galvanic series.

b. Make connections with clean, bare metal at points of contact.

c. Coat and seal connections having dissimilar metals with inert material to prevent future penetration of

moisture to contact surfaces.

d. Use hydraulic compression tools to provide correct circumferential pressure for compression connectors. Use

tools and dies recommended by manufacturer of connectors. Provide embossing die code or other standard

method to make a visible indication that a connector has been adequately compressed on earthing conductor.

e. Where insulated earthing conductors are connected to earthing rods or earthing bars, insulate entire area of

connection and seal against moisture penetration of insulation and cable.

f. Tighten screws and bolts for earthing and bonding connectors and terminals according to manufacturer’s

published torque tightening values.



g. Protection against Corrosion: Protect bolted connections against corrosion either by filling with Vaseline or

coating with a special anti-corrosion compound and proper capping.

h. Where earth connections are between dissimilar metals these must be made using bimetallic fittings and

protected by coating with moisture resisting bituminous paint or compound, or by wrapping with protective

tape to exclude moisture.

i. Exothermic-Welded Connections: Comply with manufacturer's written instructions. Welds that are puffed up

or that show convex surfaces indicating improper cleaning are not acceptable.

j. Tighten screws and bolts for grounding and bonding connectors and terminals according to manufacturer's

published torque-tightening values. If manufacturer's torque values are not indicated, use those specified in

applicable Standards.

8.4 Testing Of Earthing System

a. The complete installation shall be tested and inspected to ensure that it complies with the requirements of this

Specification, the IEE Wiring Regulations, British Standards and the Local Authorities. The tests shall be carried

out in accordance with the IEE

b. The earth resistance shall not exceed 1 ohm.

c. All the portal frames shall be ring earthed 50mm size and all the joint to be 35mm size and to be connected to

the main earth pit.

d. All instruments necessary for inspection and testing shall be supplied and shall be properly calibrated and

operated by personnel skilled in their use.

e. Allowance shall be made for disconnection or similar operations to satisfy the requirements for testing, etc.,

and the reinstatement of the installation.

f. Measure earth resistance not less than 2 full days after the last trace of precipitation and without the soil

being moistened by any means other than natural drainage or seepage and without any chemical treatment or

other artificial means of reducing natural earth resistance.

g. Where resistance to earth exceeds specified values, will consider for recommendations to reduce earth

resistance and to accomplish recommended work.

h. Restore surface features, at areas disturbed by work of this section. Restore areas disturbed by trenching,

storing of dirts, cable laying, and other activities to their original condition.

Testing will carried out for the followings,

a) Earth pit and earth rod - Earth resistance measurement.

b) Wires and cable grounding conductors - Continuity test.

c) Manhole earthing - Earthing resistance measurement.



9. Construction Program

As per main program

9.1 HousekeepingThe work area shall be maintained neat and tidy as reasonably practical at all times.

9.2 Protection of Executed WorksExecuted works in areas were other works are still being carried out shall be protected as per the contract requirements.

9.3 Responsibilities

PositionOverall Resp. Supervise Perform Short Description

Project Manager

Construction Manager

Project Engineer

Site Manager

Site Engineer Land Surveyor Safety Engineer

QA/QC Engineer

MEP Coordinator

General Foreman

Foreman Charge hand

Labourer Helper

9.4 RecordsIn accordance with the Quality Management System, the following records will be maintained as documentary evidence of the establishment of this method statement:

Records to be retained Responsibility Minimum Retention Period

Disposition

Work Notification( If required)

Site Manager As per ContractRequirements

Request for Inspection( RIW )

QA/QC Engineer As per ContractRequirements

10. Inspection and Testing

In Process works shall be monitored for quality of workmanship and installation against approved shop drawings by the relevant supervisor.

All works shall be inspected for conformance to specification. The inspection formats shall be used in accordance with the requirements of the main contractor UNEC. An inspection request for the installation & testing of earthing system shall be submitted one day prior to the

consultant.

11. Related Forms



As per required forms, from main contractor

12. Attachments

Risk Assessment
