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]

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

 

[elsparko]

i would swap this job for the difficulty i had on monday drilling through a granite load bearing wall for a bloody smoke alarm, wall paper walls, and wallpapered roofs , no access above, other side of wall was coving!

one of the few jobs where trunking was the solution

 

[Darkwood]

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

As hinted at the E7 supply itself could be at issue upstream of the MCB, swapping it out would hide the problem further, be interesting to get some readings off live testing.
6am start early lol... thought you Scots were made of stronger stuff

 

[elsparko]

As hinted at the E7 supply itself could be at issue upstream of the MCB, swapping it out would hide the problem further, be interesting to get some readings off live testing.
6am start early lol... thought you Scots were made of stronger stuff

if the fault is on the e7 supply itself then shirley all the heaters would fail?

 

[Darkwood]

if the fault is on the e7 supply itself then shirley all the heaters would fail?

I'm not called Shirley ....
-not necessarily, the effected mcb may have the heaviest load thus arcing of the L or N would create a larger transient on the heaviest load, it is not usually an issue with resistive loads so it may be a long shot but not something I would rule out without checking.

 

[LT21]

Fault found

Fault is with BSEN60947-3 100amp main switch arcing live conductor

While testing incoming voltage with multimeter I had clamp meter on out going supply

Voltage fluctuating between 235v and 210v resulting in outgoing supply to heater going up and down between 13 and 16amp causing MCB to overheat

There were no visible signs of overheating on MCB or main switch I broke Main switch apart see photo

 

[buzzlightyear]

will done LT21,if that had been done in the beginning then it would not be a 6th visit would it not .

 

[LT21]

Turn of events for 5 visits

1 visit
Call out storage heater not working
Tested storage heater and circuit found to be fault with circuit live to earth dead short
(Electrician 1)

2 visit
Install new supply to existing storage heater
(Deakon)
Storage heater worked for 4 days

3 visit
Tripped next day tested circuit and storage heater no fault found Presumed storage heater glitch ( cold damp Etc ) reset MCB ( Deakon)

4 visit
Tripped next day tested circuit ran temp supply to storage heater worked ok for 1 hour
Deakon wrongly diagnosed fault must be with heater ( we have all made miskates )

5 visit
Replace storage heater
Deakon

6vist
Test E7 incoming supply when E7 fault found
( Me )

I don’t think this turn of events is unreasonable for 6 visits granted on the 4th more investigation could have been done
But with E7 you are limited to what you can do with testing

I understand why the customers son in law came to you for advise ( Steve ) after 5 visits and I only came on here after he told me about all the negative comments and slagging off that was being targeted towards us as a company most off the comments were a load of rubbish

 

[Deleted account]

Well done.
That one would have had me stumped too.

It was a set of bizarre issues that I have learnt from and will remember if ever I get an issue like this.

I think the customer should be pleased with the determination to find and rectify the issue.

Some would have taken the money and run. You are obviously a professional with a reputation to keep.

 

[buzzlightyear]

I understand why the customers son in law came to you for advise ( Steve ) after 5 visits and I only came on here after he told me about all the negative comments and slagging off that was being targeted towards us as a company most off the comments were a load of rubbish

stick they head in a lions mouth ,what do you get!!!!!

 

[polo1]

Glad you found it, and as several had said, an unusual problem which would have stumped many electricians on initial investigation.
Good too that we all get to find out the source of the problem - another possible issue to add to our list of “ it might be.....”!