10 way split load consumer unit problem

[Pinnacle]

I managed to trip a fuse in my consumer due to old brittle insulation breaking and earthing out after fitting a new light.

I have this unit

Comsumer unit

• Pinnacle
• 27 Jul 2010
• 2

10 way split load

But the issue I have is the tripped switch does not turn back on, even if you turn the entire consumer unit power off.

Do I need to get someone in to sort this or is it something I can fix myself.

 

[majorevent]

I managed to trip a fuse in my consumer due to old brittle insulation breaking and earthing out after fitting a new light.

get an electrician in to test the circuit, if the light fittings cable ( what you can see) is so brittle what is the condition of the cable you cant see. the electrician can do a insulation test. this is a stress test for the cables and will show how good the rest of the insulation on you cables are.

 

[LoveRocket]

What won't reset, an MCB on an RCD?

If it won't reset even with the mainswitch off, then you'll need a new breaker.

PS. I don't like the sound of those brittle cables, are they sheathed in rubber?

 

[MalcofArabia]

Might find that even though you have isolated the supply it still trips the RCD because you have a neutral/earth fault.

Really though if that circuit is brittle due to age and it's just a light, think how a cooker or ring circuit might be!!! Best to get a sparks in to check over the system sooner rather than later

 

[ban-all-sheds]

get an electrician in to test the circuit, if the light fittings cable ( what you can see) is so brittle what is the condition of the cable you cant see. the electrician can do a insulation test. this is a stress test for the cables and will show how good the rest of the insulation on you cables are.

Really though if that circuit is brittle due to age and it's just a light, think how a cooker or ring circuit might be!!! Best to get a sparks in to check over the system sooner rather than later

This doom'n'gloom might be a bit over-doomy'n'gloomy - cables to light fittings often become very brittle in the vicinity of the fittings because of the head from the lamps, and it doesn't necessarily mean that the entire installation is like that.

Pinnacle - cut back the cable to past the point where the insulation was brittle and try again. You might end up needing to get your installation checked, but cutting back to clean cable might well fix it.

 

[MalcofArabia]

Fair point Ban I always associate the word brittle with the old VIR cable but quite right PVC can burn and get brittle.

Cheers

 

[ricicle]

Is it a single MCB that won't reset or is it an RCD. If by any chance it is the latter then some makes need to be switched fully off before being able to be reset.

 

[Pinnacle]

It's a single MCB that won't reset.

 

[LoveRocket]

It's a single MCB that won't reset.

Well the MCB is knackered and you'll have to get a new one.

 

[Pinnacle]

Thanks guys.

The light is on the 1st fllor which means the lighting wires runs through the loft so easy to replace the cables if required.

I'll get an MCB (I assuem that's Master Control Breaker, right ?).

Next question is, how do take the old one out and put a new one in?.

 

[Pinnacle]

minature circuit breaker. A little knowledge goes a long way .

Looking to see if I can fine a replacement one locally.

 

[Taylortwocities]

Looking to see if I can fine a replacement one locally.

That looks like a Wylex board. Probably the most commow type. You'll get breakers at any electrical wholesaler. and online just about anywhere. Only buy an exact replacement. Do not buy another make (it probably won't fit) and do not be tempted to use a different current rating. If the old one is a Wylex B6 then get a new Wylex B6.

If you are going to do this yourself. PLEASE turn off the main switch and use safe isolating procedures to make sure everything is off. (see //www.diynot.com/forums/viewtopic.php?t=7553).

Also still be careful, the supply tails are still live even with the main switch off.

 

[kai]

You can find Wylex breakers at you local B&Q store, around a fiver each.
Many modern Wylex boards have "Easyfit breaker replacement" where you switch everything off, and detach the circuit phase cable core from the top of the old breaker, slacken off the lower busbar mounting screw fully, and the breaker lifts straight off the din-rail. Holding the new breaker, slacken off its bottom screw fully, carefully lower it onto the din rail, taking care that screw sits snugly in the busbar opening below it, press it onto the din rail, and carefull tighten the lower clamping screw, reattach the phase cable core, and test as required, then replace front lid and job done.

 

[Pinnacle]

Thanks Taylor,

I've bought and installed a new mcb. However I still have a problem. I think I need to tell the story from the start to have be able to recieve the best help.

3 bedroom terrace house. Upstairs lights as follows:
Hallway
Bathroom
Bedroom 1
Bedroom 2
Bedroom 3

Had a standard light with lamp shade in my daughters room (Bedroom 1). Went to Ikea and my daughter wanted one of those Sun lights which takes 3 x 40w bulbs. So got home and turned off the power (complete electrics not just the lights, i.e. double red switch). Unscrewed the existing light to find 2 black wires twisted together into the live and 1 black wire plugged into the neutral. So fitting the new light I found that the two wires twisted together were to thick to fit into the live terminal. I used an insulated block to connect these two wires to a single wire and then into the live, the nuteral into the nuteral. Electricity back on and all works fine.
A few hours later the light had been on and off a few times during this period, my wife turned the light on and bedroom 2 light went off. I checked the consumer unit and there was a switch tripped. As this was the only electrics I had touched the problem had to be there. I turned the power off again (leaving the tripped switch off). Examined the wire and found the earth had broken insulation and was earthing out on a piece of ceiling wood. Insulated all back up and tried to reset the switches. The blown one would not turn on again even though the main power was off. Tried turning the main power back on and the resetting but still no good. in the meantime I noticed that the light still worked in bedroom 1.

So at this stage Hallway and Bedroom 1 lights work.
Bedroom 2 , bedroom 3 and bathroom not working.

Replace the MCB and turned on, all good, but still no light in bedroom 2, 3 & batchroom.

So I now have no tripped switches and three rooms without lights. I'm trying to think how the loop wiring is working so I can figure out what to check next.

Can you assist?

 

[LoveRocket]

T Tried turning the main power back on and the resetting but still no good. in the meantime I noticed that the light still worked in bedroom 1.

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!