Multiple conductors connected to MCB's

dandb · Nov 30, 2010

Visited chaps house today for work, and noticed in the CU the following cables connected to MCB's, previous occupier had CU fitted 14 years ago.

Lights Downstairs - 3 conductors connected. They were for I presume, as I didnt run any checks, Hallway, living area and kitchen diner.

RM upstairs and RM downstairs - both had 4 conductors connected.

I am a little baffled to why this is as its only a 2 up 2 down house.

Surely the chaps who fitted the CU didnt used a RM for living area, RM for kitchen diner on one MCB. RM for bedroom 1 and RM for bedroom 2 on other MCB. MCB's are RCD protected/

Anyone come across anything similar? And if so did you advise customer investigation work is needed to identify conductors correctly?

Thanks for you time

ezzzekiel · Nov 30, 2010

prob spurs added to circuits, do cont tests to identify ring legs then trace whats powered from others.

IQ Electrical · Nov 30, 2010

dandb said:
Visited chaps house today for work, and noticed in the CU the following cables connected to MCB's, previous occupier had CU fitted 14 years ago.

Lights Downstairs - 3 conductors connected. They were for I presume, as I didnt run any checks, Hallway, living area and kitchen diner.

RM upstairs and RM downstairs - both had 4 conductors connected.

I am a little baffled to why this is as its only a 2 up 2 down house.

Surely the chaps who fitted the CU didnt used a RM for living area, RM for kitchen diner on one MCB. RM for bedroom 1 and RM for bedroom 2 on other MCB. MCB's are RCD protected/

Anyone come across anything similar? And if so did you advise customer investigation work is needed to identify conductors correctly?

Thanks for you time

Welcome to domestic installation work!

The extra cables could be many things, likely suspects are doorbell transformers and intruder alarm systems.

A spur can be taken from an accessory, a junction box or the origin of a circuit, that might explain 3 cables at a device for a ring final but not 4.

You don't say exactly what you were doing there so it's difficult to define your responsibilities but I'd be encouraging the customer to book a periodic inspection.