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

[elsparko]

Would have been fine if the fence posts were taller!

i think it was a deer but may have been a cow, this is war story that was swapped so never seen it first hand

 

[KEV 1 N]

i think it was a deer but may have been a cow, this is war story that was swapped so never seen it first hand

I can believe it, it’s the sort of thing a farmer would do as opposed to spending money!

 

[elsparko]

I can believe it, it’s the sort of thing a farmer would do as opposed to spending money!

why should he shell out for insulated copper when he has an almost infinite supply of steel fence wire?

bloody farmers...

 

[KEV 1 N]

why should he shell out for insulated copper when he has an almost infinite supply of steel fence wire?

bloody farmers...

Haha! There’s a bloke at our place keeps horses (or used to when there was money in them!) He fitted some lights in a farmers barn......his payment?
Three bails of hay!

 

[buzzlightyear]

this post is now getting like one that flew over the cuckoos nest.

 

[KEV 1 N]

this post is now getting like one that flew over the cuckoos nest.

A classic!

 

[SparkyChick]

Could it not be (as @Murdoch has also hinted) that it's simply a case of the MCBs in the E7 board are getting a little past it?

7 hours a day running near the limit for extended periods of time is going to have some effect on the bi-metal strip.

If they've been thorough and the heater checks out, the cabling etc. checks out and it doesn't trip on an MCB in the 24 hour board, really that leaves only one thing... the MCB in the E7 board. Change the one feeding the heater that causes the trips for a new one and see if that solves it.

 

[buzzlightyear]

If they've been thorough and the heater checks out, the cabling etc. checks out and it doesn't trip on an MCB in the 24 hour board, really that leaves only one thing... the MCB in the E7 board. Change the one feeding the heater that causes the trips for a new one and see if that solves it.

how can 5 sparks not work out were the fault lies .not very good is it .

 

[Bob Geldoff1234]

If i was trying to fault find this i would do the following.
1.Clamp meter the live cable feeding the heater to find out the current it is pulling.
2.Change the 20 amp switch.
3.Change the flex feeding the heater.
4.Depending on the current try fitting a 20 amp breaker instead.

The other difference between day time running and night is the temperature drop during the night.It might have something to do with it?Maybe not.

From what i can read from this,then my guess is that the day time running(when its not tripping) is not run for long enough for the fault to develop.ie. 3 hours into the night the breaker trips.Day time half an hour running everything seems ok.
Like others have said failing all the above,run a temporary wire to the heater to see if this helps and if so then rewire it.

 

[marconi]

Reading the symptoms and what has been tried out I reckon the problem is the MCB for the large NSH (3.4kW) is of inadequate rating for the load current 14A at 240V. The E7 board does not take into account derating of this MCB for grouping and ambient temperature. In service it has too low a rating for its load current and its situation alongside 3 other MCBs through which steady currents of circa 10-14A are flowing for prolonged periods. It is not surprising they are getting warm, and that the one that trips first is the one through the highest current is flowing for the large NSH.

Switching the large NSH to the 24/7 board I guess powers it from an MCB which is situated alongside only lightly loaded MCBs - it can more readily dissipate the Ohmic heat and thus has a higher in-service rating.

The answer if possible is to swap the MCBs for 20A ones - a study will have to be done on the E7 cabling and its installation method to ensure this is safe to do.

see this piece on Hager MCBs for more information:

 

[elsparko]

Could it not be (as @Murdoch has also hinted) that it's simply a case of the MCBs in the E7 board are getting a little past it?

7 hours a day running near the limit for extended periods of time is going to have some effect on the bi-metal strip.

If they've been thorough and the heater checks out, the cabling etc. checks out and it doesn't trip on an MCB in the 24 hour board, really that leaves only one thing... the MCB in the E7 board. Change the one feeding the heater that causes the trips for a new one and see if that solves it.

but all e7 mcbs going at the same time would seem very unlikely, from what i gather they have tried putting the circuit into other mcbs in the e7 board and all have tripped with the troublesome heater/circuit

i think we have all given our fair share of free advice

 

[Toneyz]

Could it not be (as @Murdoch has also hinted) that it's simply a case of the MCBs in the E7 board are getting a little past it?

7 hours a day running near the limit for extended periods of time is going to have some effect on the bi-metal strip.

If they've been thorough and the heater checks out, the cabling etc. checks out and it doesn't trip on an MCB in the 24 hour board, really that leaves only one thing... the MCB in the E7 board. Change the one feeding the heater that causes the trips for a new one and see if that solves it.

Has this not been tried on the using the other MCB's in the E7 board

 

[buzzlightyear]

we are all speculating what if or may be that .if all else fails bin it .

 

[buzzlightyear]

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??

faulty fuse change !

 

[DC-backfrom the past]

If all relevant testing has been done and nothing shows up.
the heater works on other board ok .
then I would try and replace the relevant mcb that's tripping for a new one or one from the other board if it fits. I believe Murdoch has pointed that out already.

this seems to be the most obvious problem that's staring out.....providing all information to date is correct.

 

[Octopus]

Could the op post a picture of the E7 board and the 247 board?

 

[ipf]

Pretty sure its a 15amp MCB. The point is the particular heater trips any of the 15 MCB's on the E7 board they put it into (the other night storage heaters don't), but the heater does not trip any of the 15 amp MCB's on the main fuseboard when they wire it to that.

Just noticed...if they are 15amp breakers, the unit is getting on a bit. Are you sure they aren't 16 amp?

 

[PEG]

Just noticed...if they are 15amp breakers, the unit is getting on a bit. Are you sure they aren't 16 amp?

Bingo! ...and finally,someone spots the detail,that leads me to believe,the OP is a bit more "involved",than we think

 

[dmxtothemax]

If it is an over current situation ? Then maybe the normal system is better able to provide the high currents needed, which is why it does not trip, but the E7 system is clearly struggling, it might be choking a bit causing currents to rise. You need to do a good low resistance check on both systems, i bet the E7 system has a higher reading !
QUOTE - [when you have eliminated the impossible, whatever remains, however improbable, must be the truth ! ]

 

[Deleted member 9648]

is an intermittent lighting fault one that occurs only when switched on but fine if left off. ?

Bang on...(pun intended)...was a big old house, turned out to be a PIR buried under ivy and unknown to the householder, what it switched on was also unknown, but a L-E fault on the switched side led to a JB under the floor where the cable with the fault could be disconnected. Testing at the DB was clear, but every night at some point the mcb would pop when the PIR activated. A poxy job to trace that one.