How many cables should be in the back of a socket?


Postby Al223 » Wed Jan 07, 2009 10:16 am

I was going to install some extra sockets in my living room, but found that the socket I was planning on extending the ring main from appeared to be a spur, with only one cable in the back of it, the other socket in the living room has 4 cables all plugged into the connections on the back of it.

My understanding is that if only one spur can be run from a socket on a ring main, surely there should only be three cables maximum?

This lead me to thinking that perhaps the wiring is in fact a radial circuit. Is there an easy way to check this?

Assuming all 4 cables are needed, is there any circuit, which would be allowed under current regulations which would require all four cables?

Thanks in advance for all help received.
Al223
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Joined: Wed Jan 07, 2009 10:06 am

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Postby ericmark » Wed Jan 07, 2009 8:43 pm

Go to http://www.theiet.org/publishing/wiring ... s/updates/ and down load the BS 7671:2008, Corrigendum (July 2008) at the end of this there is a chart showing exactly what can be done.
Two things need noting size of cable and size of overload protection. I would not think you would get 4 x 4mm cables into a socket so I would assume wired in 2.5mm and this is rated around 22 amp so on a 32 amp MCB either it needs to be doubled up as in a ring main or only supply one socket and even with a double this limits output to 26 amps.
It is not normal to take two spurs from one socket if one wanted to do this one would normally fit two sockets close together both being part of ring and one spur of each or use a FCU (fused connection unit) which then limits total to 13 amp.
With power isolated (Not just the MCB off) using a meter to bell cables there should be a connection between both lines, both neutrals, and both earths and I would always test for this before adding another socket.
Also now all sockets under 20 amp need RCD protection.
Eric
ericmark


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