Order of Testing

Question 1

Order

Answer 1

1.Continuity of earthing conductors (r1+r2)
2. Continuity of a ring circuit
3. Insulation resistance test
4.Polarity
5. Earth fault loop impedance
6. Prospective fault current
RCD
7. Phase rotation

Question 2

Continuity of earthing conductors

Answer 2

Dead - done first to ensure all CPC are continuous, if they were not the remainder of the tests would not test a full circuit.

Question 3

Continuity of ring final circuit

Answer 3

Dead - ensures all conductors in a ring circuit are continuous, if they were not the remainder of the tests would not test the entire circuit

Question 4

Insulation resistance test

Answer 4

Dead - ensures there are no short circuits or shorts to earth before energising the supply

Question 5

Polarity

Answer 5

Dead - usually carried out in continuity of protective conductors method 1, ensures all electrical connections have the correct polarity, done before the power is switched on to prevent damage to equipment

Question 6

Earth fault loop impedance

Answer 6

Live - impedance has to be low to ensure protective devices trip, devices must trip in the required time of 0.4s for 32A and less and sockets up to 63A, 5s for all other circuits. (verified using table 41.2-41.4 of regs)

Question 7

Prospective fault current

Answer 7

Live - indicates short circuit current fault, done to ensure all protective devices can stop large fault current and will not cause the device to arc

Question 8

RCD

Answer 8

Live - carried out to ensure the RCD will trip within the required time of 40mS or less for a fault 5 times the value of the RCD device

Question 9

Phase rotation

Answer 9

Live - checked at the source to ensure all 3ph motors are spinning in the correct direction