Neutral conductors terminated in lighting switch enclosers

It is a misconception that a neutral conductor jointed or terminated in a lighting switch enclosure is an unsatisfactory method of installation.

Solution

Where a wiring system employs thermoplastic-insulated and sheathed twin and earth flat cable, it is an acceptable practice to loop-in at the switch and connect the neutral conductors in the lighting switch enclosure. However, no less than for other conductors, a connection made in the neutral conductor should be durable in terms of electrical continuity and mechanical strength (Regulation 526.1 refers). Furthermore, an enclosure should provide the connection with adequate protection against mechanical stresses (such as cable movement) and end environmental protection (such as the presence of water), as required by Regulation 526.7.

Alternatively, the installer may have fitted a double-pole switching device to terminate both the line and neutral conductors at the lighting switch enclosure.

Where during periodic inspection reporting, a neutral conductor is encountered in a slighting switch enclosure, provided there is a durable connection meeting the requirements of Regulation 526.1, or a double-pole switching device is present, no departure from BS 7671 should be recorded by the inspector, against the neutral conductor.

Regulation 526.1

Every connection between conductors or between a conductor and other equipment shall provide durable electrical continuity and adequate mechanical strength and protection.

Regulation 526.7

Where a connection is made in an enclosure the enclosure shall provide adequate mechanical protection and protection against relevant external influences.