10 way split load consumer unit problem

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So bedroom 1's light worked even with the lighting MCB off? That's not good. You either have that lighting fed from a socket circuit or the downstairs lighting circuit. Turn other MCBs off one at a time and see what one causes the light to go out.

As for the earth wire earthing out on a bit of ceiling wood, that's a nonsensical statement. The CPC ("earth wire") is at earth potential, so can't "earth out", especially not to a non-conductive material like wood!
IF the CPC comes in to contact with a phase conductor ("live") then it would trip the MCB, is that what happened do you think?

There MUST be some reds up there above the light. The two blacks are the neutrals (one from the CU, one to the next light), and the single black is the switched-live coming back from the switch. There will likely be 3 reds connected together, one from the T+E to the switch, one from the T+E supply from CU, and one from the T+E to the next light. This is the most likely cause of your original, and current problem. Get up there and check!

It's possible that the fault has blown a connection somewhere. Start by removing and inspecting behind each ceiling rose (or switch if the looping is done in there), and check if there's any junction boxes up in the loft.

Work safely and good luck!

PS. A photo's worth a thousand words! ;)

Ok strange one here. Turned the light on in Bedroom 1. Asked the wife to tell me when it whent off as I flicked the switches one by one. My consumer unit has a bunch of 6AMP on one side and then a bunch of 32AMP on the other (no other fuses just 6 and 32). I flicked each one of the 6AMP off one by one leaving each one off. The light stayed on even though all the switches on the 6AMP were off. Next I switched the RCD off for that side of the board. Only now did it turn off.

I guess you are right it must have been the live wire must have touched the CPC above the light.

Ok, Would it help if I take a picture of the wiring of each switch and ceiling rose in each room and also a picture of the wiring up in the loft ?

If so I'll start taking these tonight.
 
Do all of your live wires go to the same point in each of the MCB's. ie you havent got one thats wired to the main bus bar side of the MCB
 
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Please stop calling MCBs "switches" or "fuses".

Thanks.

Get some photos. What MCB turned the light off (rather than switching the RCD which does the whole bank)?
 
Problem fixed.

Powered off. I headed up into the loft with a torch (loft light not working either). Worked out that that the ring went as follows:
Hallway, bedroom 1, bedroom 2, bedroom 3, bathroom, loft.

The lighting in my house is a mess. I found the following:

Hall light wires go directly down to the light from the ceiling (i.e. feed in, feed out and switch i.e. 6 wires).
Bedroom 1 loop wires were connected together in the loft and fed the two negatives and switched live down through the ceiling to the light.
Bedroom 2 were all connected via a junction box in the loft and then fed a separate live neutral and earth wire down through the ceiling.
Bedroom 3 fed all wires down into the light
Bathroom fed all wires down into the light
Loft had a light switch fitted using only the feed in live wire i.e. neutral went straight from the Bathroom feed to a bulb holder.

The really scary thing is that none of the earth wires in these lights were connected to anything.

I've read a whole lot of information about lighting and how it should all be wired up, to the point that I'm interested in rewiring the lighting using junction boxes above each room. If I use the existing wires and just fit junction boxes, do I need to get this signed off, ok I know I should really get it signed off, but in effect all I'm doing is standardising the wiring without changing the load. What I'm saying is can I get away with not signing it off if I use the same wiring but new junction boxes ?
 
You do not have to get it notified.
The work you are doing is not in a special location.......

However I would recommend that you carry out the necessary tests (including earth continuity). Just because it works doesn't mean it is correct.

And please please:

Lighting circuits are not rings, they are radials

AC (mains electricity) does not have a negative. It has neutral and live (some say line, some say phase) but it is never positive and negative - that's for cars and bikes.

Well done for sorting it though.
 

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