consumer unit problem

[deckertim]

Various members of our family have been noticing a burning smell in our cellar for a week or so. I just found out the reason.

a pretty sight and obviously could have started a fire.

The most annoying thing is that this is on a connector that is factory fitted. This has also been working fine since it was fitted in early May. I am also fairly sure that the electrician tightened up every screw!

In the experience of the group is this just bad luck? Can electrical screws work themselves loose?

I have contacted Contactum asking if I can get a replacement, but haven't had a reply yet. A new one from TLC costs about =A338, but ideally I would want one without any switches or RCD.

[John White]

Looking at the picture it appears that the conductor in "N1" does not pass right through the bar, unlike the one in "N2".

If this is the case then the screw, although tightened correctly, may have only clamped a small part of the conductor into the joint. This could in turn have led to the overheating.

The instructions that come with consumer units usually state that the installer should check all the connections - including the factory ones. I suspect Contactum will just point this out and throw the problem back at yourself.

Why don't you just ask the electrician who did the work in May, to come back and put it right? Presumably it's still under guarantee and ought therefore be replaced at no cost to yourself.

Well it does happen, but it's very unusual in domestic situations, and it would normally take more than four months anyway.

Daft as it might seem, you may find that an empty box costs more than one with the main switch and RCD fitted.

John

[John Rumm]

As you say not nice, although all the materials used ought to be self extinguishing if it is any consolation.

You do have to get them very tight and it is easy to miss one if you don't go back over them several times. The actual general quality of the workmanship looks pretty good though on the bits we can see in the photo IMO.

Out of interest, The last split load contactum box I used came pre-wired completely wrongly! I can't actually remeber what they had done now, but I do recall it would have done something fairly drastic (i.e. take out the main fuse or reverse polarity on one side) if any attempt had been made to power it up as supplied.

Screws can and do work loose - more so if they are being thermally cycled. It only takes a very small resistance at a point of contact if you have a high current connection to get localised heating.

Your source of heat there looks like it is coming from the neutral connection that goes to the RCD, and hence is carrying the the full load of all the circuits on the RCD protected side. It is also a metal sleaved wire which can be harder to get a good screw connection onto.

Failing that a new neutral bus bar and connection wire to the RCD would probably be enough to make it safe. The droopy plastic does not look good, but it is not so bad that it is exposing live parts or anything.

[Dave Plowman (News)]

Instructions for every CU I've seen say to check and tighten factory installed links. I've often thought the links should be supplied but not installed at all from the factory.

[Christian McArdle]

The neutral bar ones are quite difficult to get tight, as there is no give on the hefty link.

Having got pretty much an identical non-split unit, with a similarly solid (but different) neutral link, I'm tempted to go back and replace with stranded 16mm cable.

As it happens, for me the right hand block contains all the 32A circuits, with only small circuits after the link, so I'm much less likely to get a problem than on a split unit, with all the 32A socket circuits after the link.

Christian.

[Fash]

Just out of interest which circuits have 3 live wires running into them? Just intrigued that's all.

Fash

[Christian McArdle]

Frequently this would be a ring circuit with a spur taken from source. Plenty of other possibilities.

Christian.

[deckertim]

One is the upstairs lights. The other is for fridges and freezers feeding three separate sockets.

Thanks to everyone for advice. I have just turned off the power and trimmed back the ends of some of the neutrals where the insulation was a little melted. I also had to replace one earth sleeve that had also got a little melted. I was also able to tighten up all the connectors and ensure that the main neutral feed that caused the orginal problem was cleaned up and pushed in further. So no safety problems now. However the outside case has got a section that is a bit melted. Obviously this would be picked up in any basic home inspection/survey so will need replacing. I will let you know how I get on with Contactum, especially as I know they don't answer emails.

Tim

[Dave Plowman (News)]

Send them a fax from your computer. That usually works...

[Stephen Dawson]

a pretty sight and obviously could have started a fire.

The most annoying thing is that this is on a connector that is factory fitted. This has also been working fine since it was fitted in early May. I am also fairly sure that the electrician tightened up every screw!

In the experience of the group is this just bad luck? Can electrical screws work themselves loose?

I have contacted Contactum asking if I can get a replacement, but haven't had a reply yet. A new one from TLC costs about £38, but ideally I would want one without any switches or RCD.

Tim,

As this was fitted in May, was the electrical contractor registered for Part P?? If so, did he offer you a warranty?? He should have. Make a claim on the warranty for a new consumer unit as the neutral terminal has not been checked for tightness. The electrician who did this job should replace it FOC.

Regards

Steve Dawson

[deckertim]

Very good point. Without wanting to incriminate anyone, paticularly myself, I probably won't be chasing the guy who did this work. Sorry if I gave the impression this was done in May this year, it was of course done in May 2004!

Thanks

Tim

[Martin Pentreath]

Ooooh, naughty! You'd never catch me up to such tricks.

[Jim Alexander]

Someone off the mark quickly with the new harmonised colours then.

Jim A

[Guy King]

The message from "Jim Alexander" contains these words:

He may have replaced like with like.