Page 65 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 25 : Testing of protective multiple earthing

(PME) connection

Objectives
At the end of this exercise you shall be able to
• identify and test the Earthing installations
• measure the earth potential between phase & neutral
• connect and test the protective multiple earthing (PME) system.

Requirements

Tools/Equipments Materials
• Combination Plier (165mm, insulated) - 1 No. • PVC copper wire 1.5 sq.mm - as reqd
• Screw Driver 150mm - 1 No. • Test lamp 100 W, 230 V - 1 No.
• Neon Tester 75mm, 500 V - 1 No.
• Electrician knife Insulated - 1 No.
• Multi meter Digital, 3 digit - 1 No.
1/2

Procedure

Protective Multiple Earthing (PME) system : It is a method of earthing system in which an earth conductor is
connected to the earthing point as well as neutral wire of main incoming supply. In this type of connection a fault
current flows to ground and ensures protection from electric shock and damage of equipments in the event of
failure/break of main supply neutral wire. This method is often used in power supply & distribution networks.
TASK 1 : Check the earth continuity
1 Draw the connection diagram of protective multiple earthing (PME) system.
2 Identify and test the earthing installation/s for working condition with test lamp.

3 Identify the main input supply and load switch of electrical installation.

TASK 2 : Connect and test the protective multiple earthing (PME) circuit
1 Switch OFF the main incoming supply of electrical installation.

2 Connect the earth conductor parallel to the earthing point and main neutral wire.
3 Check the connection and switch ON the supply, measure the earth potential with phase & neutral.
4 Test the PME circuit by breaking / disconnection of neutral wire and measure the voltage and current in the
load circuit.
Safety precautions:
1 Do not make connection with live supply.
2 Do not make wrong & loose connections.

3 Ensure proper continuity of earth source.

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