Totally stumped. Night Storage Heater tripping out MCB, but ok on daytime circuit.

[Steve Poulton]

Please help. I have a basic understanding of electirics, but 5 Electricians are stumped and I don't know where to go next. My mother in law heats her house by 4 Night Storage Heaters, all of which are wired to a Economy 7 supply/fuse board, with no RCD just MCB. The largest of the Night Storage Heaters began to fail and trip the MCD. To cut a long story short, she ended up having a new one fitted. Unfortunately this new one also now trips the MCB. The electricians have tried swapping the various supplies to the various heaters around in the E7 fuse board and the same heater is tripping the different MCB. It would be an obvious thing to consider that there is a fault on the circuit between the board and the night storage heater. However, they have now wired it into the day time board and it is not tripping. Has anyone got any ideas as we need to get it wired back into the E7 circuit??

 

[elsparko]

E7 still on at that time

i know but still, you could just temporaily connect the tails from the E7 board into the 24h henleys

 

[AJshep]

Other factors I'd look out for.

It's cold at night when E7 kicks in could be that the heater is on a outside damp wall and the Elements are getting a little damp. Is it under a window that's dripping with condensation ?
I suppose It might explain the funny readings Deacon got when originally testing the heater.

I hope you find it you never know you might find a load of washing on it when you go round in the morning.

 

[Lucien Nunes]

Wow - 93 posts before the subject of MCB heat dissipation surfaces and its effect on rating - was in my mind halfway through the OP (apologies if I've missed an earlier mention). Might not be the problem here but needed consideration. By post 111 I thought it was a good thing that someone summarised the points that people kept missing, only to find the laws of physics being cruelly twisted instead.

Thankfully I pledged early on not to get involved. Increasing spring tension seemed a likely cause - not the ones in the MCBs but like the one in my gramophone!

 

[Octopus]

139 posts and why do I get the feeling we are not being told everything ........ by the various people involved?

 

[Octopus]

how did you know his name is steve ?

call me Sherlock if you want but the OP's name is Steve!

 

[elsparko]

Double post.

Jeeze guys, give the OP a break. If you don't want to help, then don't post. I guess we've all had electrical issues to deal with where the problem doesn't seem to fit normal solutions. Asking what to some might appear to be a question which has an obvious answer, doesn't mean the answer is obvious to everyone. I stupidly believe the Forum is here to help, not slag off posters at the earliest opportunity. Rant over!

As some others have suggested, your problem does appear to lie in the E7 board. Given what else has been done, I would try the largest MCB which the circuit installation/ccc will permit, located at the end/away from the other MCBs. Apologies if you have already tried this - it's starting to get difficult to ID exctly what's been done. Oh, I also suggest that you post clearly, earthing type, Ze, Zs, R1+R2 and insulation resistance of the circuit involved.

call me Sherlock if you want but the OP's name is Steve!

ill call you shirley, and you will like it.

 

[Darkwood]

Having read through the whole thread it would seem the OP's explanation of events was initially lacking in detail and difficult to get a defined sequence of events, luckily having the Electrician who went to site come to the forum and run us through what has been done we are now a little clearer.

It would seem we have 2 sparks trying to resolve this issue, one of which has kindly joined and replied to straighten a few facts up.
It seems also there has been 5 visits trying to resolve the issue which is still on going.

Regardless if it was necessary here is what we know!

-The original old heater tripped its mcb, in trying to resolve this it was swapped onto other mcb's in the board with the same effect.
-The cable to the heater, DP switch and heater have all been replaced which still cause the mcb to trip, it would seem testing (dead tests) now show no issue with the new circuit and load.
-It has been wired to 24hr supply where no issues of tripping occur even when left on all day.

What we need to know, when swapped over in the E7 board did the cable get physically swapped to a new circuit position or was one of the other mcb's just swapped leaving the circuit in the same position, if the latter then has the busbar been checked for damage and also the neutral block, a split in one of these could create arcing effecting the circuit after the split. A bent busbar tab could also mean it isn't been clamped by the mcb and could repeatedly be on the wrong side of subsequent mcb's when fitted, or simply incorrect fitting or checking of the mcb to ensure the tab is located, this was common with older mcb which naturally fell to the wrong side of the tab when been fitted.

How is the E7 provided, is it possible the tails are loose or other points in the supply chain where it may effect the heaviest load with arcing tripping the magnetic side of the mcb.

As has been mentioned, has suitable derating been applied to grouped high loaded mcb's for the temp' build up, this may only have manifested it head as the mcb's have aged..

The more info we get the better chance we have to help, MCB brands, ratings types, storage heater details etc etc, tests carried out and results, as it stands members are making presumptions and even just a small presumption can send us all off track so the more info the better even if it seems irrelevant.

 

[Deleted member 9648]

Indeed, cut the criticism lads....looking forward to hearing how this progresses. We've all had jobs where we've been stumped before. It's easy to lead yourself up the garden path and get confused.Usually sleeping on it, a fresh start next day and it's sorted in a jiffy.

 

[Darkwood]

I agree with wirepuller here, I think if any criticism is to be given we at least find out the problem, I have seen some of the most experienced lads out there get stumped by uncommon faults so lets show a little respect, leave the constructive advice/criticism to the end if at all it is needed.

 

[Toneyz]

I agree with wirepuller here, I think if any criticism is to be given we at least find out the problem, I have seen some of the most experienced lads out there get stumped by uncommon faults so lets show a little respect, leave the constructive advice/criticism to the end if at all it is needed.

Well, we might find tomorrow morning.

 

[elsparko]

I agree with wirepuller here, I think if any criticism is to be given we at least find out the problem, I have seen some of the most experienced lads out there get stumped by uncommon faults so lets show a little respect, leave the constructive advice/criticism to the end if at all it is needed.

its difficult to fault find without being on site

 

[elsparko]

i still dont see why the e7 supply needs to be live for testing, when it can easily be connected to the 24h , 6am start seems unreasonable

 

[Deleted member 9648]

its difficult to fault find without being on site

With the confusion of info here yes....but not always.

 

[buzzlightyear]

Please help. I have a basic understanding of electirics, but 5 Electricians are stumped and I don't know where to go next.

may be the op in the beginning should not throw us a curve ball.

 

[elsparko]

With the confusion of info here yes....but not always.

thats been the most frustrating thing, so unclear , no actual test results/confirmation of tests done etc