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voltage drop

Posted: Mon Jan 12, 2009 3:33 pm
by barny rogers
Power is 220/240.

I have a cable with 4cores (Red, Blue, Yellow & bare) from that I'd like to take out power to a twin wall socket.
I've cut the cable in half and joined it in a junction box from which I have taken power out via another cable (3-core Blue, Braun & earth) to the twin socket.

I have 228v to the socket but when plugging in a light, it doesn't work and measuring the voltage with the light on, gives me 141v.

Any ideas to what's happening?

Posted: Mon Jan 12, 2009 6:58 pm
by ericmark
The only place we use triple and earth cables is as strapers between light switches and between central heating boiler and cistern.
So first question is what made you think it was a power cable?
Then to work out volt drop also need cables sizes.
Sorry called away may be back latter

Posted: Mon Jan 12, 2009 7:28 pm
by barny rogers
The cable comes out of the kitchen floor and continues straight up to the first floor to a light switch in the top floor hallway.

The cable is a flat one and measures 11mm x 5mm.

I had no way to see what was inside the cable before cutting it but if it goes to only a light switch, can't I then pull out power to a 2 gang switched socket?

Posted: Mon Jan 12, 2009 8:55 pm
by barny rogers
I have now found out the cable runs between two light switches which turn the same light on/off, donno what you call this sort of cable but it apparently doesn't carry 220 all the time but drops when power is tapped from it.ou

I have to take power from an alternative source.

Thanks for your hint.

Posted: Tue Jan 13, 2009 6:37 pm
by 27col
The cable you have cut is a 2way lighting cable. No, you cannot use it to supply a double socket. It is not big enough and also the supply to it is only 5amp. You will have to find a different source to supply your socket outlet.