GENERAL
Earthing shall be installed in compliance with the PLN, PUIL Electrical Regulations, Electrical
Supply Regulations and to the contract drawings.
The earth bars shall be of adequate size, thickness and spacing from the wall to provide a
robust, efficient and electrically sound installation. Each bar shall be oversized by 20% to allow
for future connections.
Conductors of earthing equipment shall not be looped between equipment.
EARTH ELECTRODES AND EARTH MATS
Each earth electrode shall be copper rod of 16mm dia. X 3.6m long and shall have provisions
for clamping the earth lead. It shall be buried inside the ground housed inside concrete pits 300
x 300 x 250mm deep with removable concrete covers. Provide test links at each electrode to
facilitate isolation for testing of the earth electrode.
Provide earth mats as shown in the drawings.
Provide earth bars and connect to earth electrodes and mats. Interconnect earth bars as
shown in the drawings.
EARTH CONTINUITY CONDUCTOR
All earth continuity conductors shall be PVC insulated copper.
The following shall be the minimum earth continuity conductor for each current carrying
conductors:
METAL WORK EARTHING
All non-current carrying metalwork must be adequately earthed with PVC sheathed copper
wire.
All earth continuity wires connected to the earth bar or neutral link must be threaded through
the block and NOT over the block to the earth bar or neutral link.
LIGHTING POINT, POWER OUTLET, LIGHTING SWITCH AND POWER OUTLET SWITCH EARTHING
At every luminaire, power outlet, lighting switch and power outlet switch an earthing terminal
shall be provided and connected to the earth-continuity conductor of the sub-circuit circuit.
EARTHING OF SWITCHROOM
Provide a main earth bar in each main switchroom in a convenient location at approximately
300 mm above finished floor level. Each bar shall be copper and be bonded to building earth
system using single core PVC sheathed stranded copper cable, as indicated on the drawings.
EARTHING OF OTHER SERVICE
Bond all metallic services such as pipes to the nearest earth bar.
EARTHING OF ELECTRONIC EQUIPMENT AND SYSTEM
Provide a technical earth bar in local telecommunication authorities room and a security control
room.
TESTING
These tests shall be carried out not more than one week before energising the equipment. The
tests shall include but not be limited to the following:
Check the earthing system has been installed as per the contract drawings and specification.
Check each piece of equipment is earthed by connection to the nearest earth bar.
Check continuity of all earthing cables.
Check earth continuity of all equipment.
Measure and record the resistance of the overall earthing system. Minimum acceptable value
is 1 ohm.