Fuse panel hot unit, smell in corridor below?

Propah Charlie · 17 Jun 2021

Title says it all, really. There is a small grey plastic unit under the fuse box, as per attached photos. It is very warm and there is some blackening behind it on the wood panel it's fitted upon.What might this unit be and what should I do about it?

I've no idea how long it's been like this except that there has been a slight smell of what I can most closely describe as warm plastic (and possibly old wood) in the corridor where the electrical unit hangs on the wall for a few months, though still not sure if it's the fuse/meter box or summat else.

I have "home emergency" cover with my home insurance but I don't know if this situation is likely to qualify for a claim under this.

Any help appreciated!

Guitarguy · 17 Jun 2021

Am I right in thinking that it is a doorbell transformer? If it is then it would need disconnecting from wherever it’s fed from. Needs an electrician to check really

AndyPRK · 17 Jun 2021

nice supply of fuse wire

ericmark · 17 Jun 2021

I love the note giving fuse wire sizes, I think @Guitarguy is right, likely door bell related. But one can only guess, remove fuses one by one until you find which on disconnects it (allows it to cool) but likely fed from lighting circuit which would clearly leave a problem. Can't even see how cover comes off. I would think the "home emergency" cover will likely isolate it for you, but not repair it.

sparkwright · 17 Jun 2021

Black neutral wire looks a bit skinny where it enters the service head - could be that too much sheath has been removed though, as people choose to do.

JohnW2 · 17 Jun 2021

sparkwright said:
Black neutral wire looks a bit skinny where it enters the service head - could be that too much sheath has been removed though, as people choose to do.

Are you talking about the black (insulated and sheathed) 'tail' between the DNO fuse and meter? If so, despite it being black, it is hopefully not the neutral

As for conductor sizes, for what it's worth the sheath appears to be the same size as that of the red one (which, despite being red, presumably/hopefully IS the neutral) - I would guess probably a 16mm² conductor.

Kind Regards, John

sparkwright · 17 Jun 2021

JohnW2 said:
Are you talking about the black (insulated and sheathed) 'tail' between the DNO fuse and meter? If so, despite it being black, it is hopefully not the neutral

As for conductor sizes, for what it's worth the sheath appears to be the same size as that of the red one (which, despite being red, presumably/hopefully IS the neutral) - I would guess probably a 16mm² conductor.

Kind Regards, John

Yes.

Are you suggesting reversed polarity?

JohnW2 · 17 Jun 2021

sparkwright said:
Yes. Are you suggesting reversed polarity?

Not at all - I'm 'suggesting' that, by describing the cable coming out of the DNO fuse as "the black neutral", you are making the classic "DIYer's mistake" of assuming that 'black means neutral, whereas one hopes that the DNO have put their fuse in the line conductor.

So (hopefully!) 'reversed colours', not 'reversed polarity'

... but even that is 'naughty' on the part of whatever DNO person or 'meter fitter' did it!

Kind Regards, John

sparkwright · 17 Jun 2021

So are you saying there is a black cable coming from the L terminal of the service head going to the N terminal of the meter

and

a red cable coming from the N terminal of the service head going to the L terminal of the meter?

JohnW2 · 17 Jun 2021

sparkwright said:
So are you saying there is a black cable coming from the L terminal of the service head going to the N terminal of the meter .... and .... a red cable coming from the N terminal of the service head going to the L terminal of the meter?

I'm not sure of the reason for this inquisition - I merely made a fairly obvious observation

Anyway ...

... no, I certainly hope that is not the case (unless there is a compensating 'swapping' of the conductors between meter and CU). I obviously can't be sure what is going on without being there but all I was suggesting is that they had probably just used the wrong colours for the cutout-to-meter tails.

.... or are you sticking to the view that the conductor coming out of the DNO fuse is the neutral ("because it is black")?

Kind Regards, John

EFLImpudence · 17 Jun 2021

The meter would appear to be connected correctly - going by the colours - so if the cut-out is not, then ...

sparkwright · 17 Jun 2021

Re: John.

You are suggesting the cable (which happens to be black) coming out of the lefthand side of the cut out is the LIVE. Is that correct?

And this cable (which happens to be black) is going the extreme second on the left terminal of the meter which is traditionally the neutral in terminal. Correct?

No inquisition intended whatsoever, just trying to work out what's going on here, and between us we may do this.

sparkwright · 17 Jun 2021

EFLImpudence said:
The meter would appear to be connected correctly - going by the colours - so if the cut-out is not, then ...

Thank you. You explained that so well with so few words.

JohnW2 · 17 Jun 2021

sparkwright said:
Re: John. You are suggesting the cable (which happens to be black) coming out of the lefthand side of the cut out is the LIVE. Is that correct?

Well, it's not really a 'cutout' in the usual sense. It is just (as I have, with my overhead supply) a fuse holder - but, yes, I am suggesting (well hoping!) that the DNO will have put that fuseholder (hence the fuse) in the Line of their supply, not in the neutral.

sparkwright said:
And this cable (which happens to be black) is going the extreme second on the left terminal of the meter which is traditionally the neutral in terminal. Correct?

Yes, traditionally that would be the case and, as you presumably would also say, the terminal to the right of it (from which a black conductor goes to the CU) would 'traditionally be the 'neutral out' terminal.

So, if that's all correct, and if the red and black tails from meter are used 'per their colours' at the CU end (i.e. red=line and black=neutral) then, in answer to your previous question, I would then be suggesting that the entire installation had 'reversed polarity' since I find it so hard to believe that the DNO would have put the fuse in the incoming neutral (and 'identified it as neutral' with a black cable). Of course, if most of the above is correct, but the tails have been used as red=neutral and black=line within the CU, then all would be well.

sparkwright said:
No inquisition intended whatsoever, just trying to work out what's going on here, and between us we may do this.

Fair enough. To be sure what was going on, we would presumably need to (a) be certain that our assumption about the meter terminals is correct and (b) see inside the CU to see what is connected to what at the Main Switch.

Kind Regards, John

sparkwright · 17 Jun 2021

a) I don't think there is an electric meter in the land which has a terminal layout any different to L in, N in, N out, L out.

b) Would be worth looking in the CU, yet it would seem polarity is already wring by the time it gets to the meter, so if polarity was restored by the time it gets to the cu, the meter at least would still be connected wrongly.

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Fuse panel hot unit, smell in corridor below?

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