Part P BS 7671 Wiring Regulations

Question 1

According to BS 7671 18th Edition, what is the maximum disconnection time for a 230V final circuit not exceeding 32A protected by an overcurrent device?

Accepted Answer

0.4 seconds

Answer

0.2 seconds

Answer

1 second

Answer

5 seconds

Question 2

What colour is the protective conductor (earth) identified by in the harmonised cable colour code used in the UK?

Accepted Answer

Green and yellow

Answer

Blue

Answer

Brown

Answer

Grey

Question 3

BS 7671 requires RCD protection with a maximum rated residual operating current of 30mA for socket outlets rated up to 32A in which circumstance?

Accepted Answer

In all cases unless an exception applies, as per Regulation 411.3.3

Answer

Only in bathrooms

Answer

Only outdoors

Answer

Only for socket outlets on ring final circuits

Question 4

What is the minimum insulation resistance value acceptable for a circuit operating at 230V according to BS 7671?

Accepted Answer

1.0 MΩ

Answer

0.25 MΩ

Answer

0.5 MΩ

Answer

2.0 MΩ

Question 5

Under BS 7671, what is the purpose of Regulation 421.1.201 regarding arc fault detection devices (AFDDs)?

Accepted Answer

AFDDs are recommended for final circuits supplying socket outlets up to 32A in single-occupancy dwellings (AC single-phase circuits)

Answer

AFDDs are required on all circuits without exception

Answer

AFDDs replace the need for RCDs

Answer

AFDDs are only required in commercial installations

Question 6

What does the term 'TN-C-S' refer to in BS 7671?

Accepted Answer

An earthing system where the supply neutral and earth are combined in the supply cable (PEN conductor) and separated at the origin of the installation

Answer

A type of circuit breaker

Answer

A testing procedure for three-phase installations

Answer

A type of emergency lighting system