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??

--
for full context, visit https://www.homeownershub.com/uk-diy...t-1257719-.htm

On Tuesday, 19 December 2017 17:44:05 UTC, Steve Poulton wrote:
The electricians have tried swapping the various supplies to the various
heaters around in the E7 fuse board

Whoever those 5 individuals were, they weren't electricians. An electrician would test the heater, circuit, and MCB using a calibrated test meter. Swappin things around and hoping they don't go bang is not a suitable test methodology [1]

I'm going to guess a phase-earth fault on the heater circuit and a reversed phase-neutral incomer on the daytime board (or vice versa) so the fault presents as a neutral-earth on the daytime board, which does not trip the MCB (but would trip an RCD).

Simple polarity testing at the various locations would rule that out.

Owain

[1] For electricians, it works fine in computer repair :-)

The question is though, if this has been in place on the old heater all that
time how come its suddenly reversed? I'd imagine this is the mindset which
has caused the confusion. It might have been wrong for years but only showed
up due to a fault and some components in the new heater are causing it to
still show up, It can be very dangerous to assume that just cos it used to
be fine, that the wiring was always correct.

Brian

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On Tuesday, 19 December 2017 17:44:05 UTC, Steve Poulton wrote:
The electricians have tried swapping the various supplies to the various
heaters around in the E7 fuse board

Whoever those 5 individuals were, they weren't electricians. An
electrician would test the heater, circuit, and MCB using a calibrated
test meter. Swappin things around and hoping they don't go bang is not a
suitable test methodology [1]

I'm going to guess a phase-earth fault on the heater circuit and a
reversed phase-neutral incomer on the daytime board (or vice versa) so the
fault presents as a neutral-earth on the daytime board, which does not
trip the MCB (but would trip an RCD).

Simple polarity testing at the various locations would rule that out.

Owain

[1] For electricians, it works fine in computer repair :-)

On Tuesday, 19 December 2017 17:44:05 UTC, Steve Poulton wrote:
Please help. I have a basic understanding of electirics, but 5 Electricians
are stumped and I don't know where to go next.
for full context, visit https://www.homeownershub.com/uk-diy...t-1257719-.htm

There's even more context at

https://www.electriciansforums.co.uk...ircuit.124737/

So far possibilities seem to be (a) a polarity error as I suggested - possibly introduced due to a meter change - or old 15A MCBs overheating and thermal tripping.

Owain

On 20/12/2017 10:32, wrote:
On Tuesday, 19 December 2017 17:44:05 UTC, Steve Poulton wrote:
Please help. I have a basic understanding of electirics, but 5 Electricians
are stumped and I don't know where to go next.
for full context, visit https://www.homeownershub.com/uk-diy...t-1257719-.htm

There's even more context at

https://www.electriciansforums.co.uk...ircuit.124737/

So far possibilities seem to be (a) a polarity error as I suggested - possibly introduced due to a meter change - or old 15A MCBs overheating and thermal tripping.

The polarity error is possible, but it seems hard to believe that none
of the visiting sparks have done a continuity test between L+N and E on
the circuit and the heater (even if they did not do a full insulation
resistance test).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 20/12/2017 12:06, John Rumm wrote:
On 20/12/2017 10:32, wrote:
On Tuesday, 19 December 2017 17:44:05 UTC, Steve PoultonÂ* wrote:
Please help. I have a basic understanding of electirics, but 5
Electricians
are stumped and I don't know where to go next.
for full context, visit
https://www.homeownershub.com/uk-diy...t-1257719-.htm


There's even more context at

https://www.electriciansforums.co.uk...ircuit.124737/


So far possibilities seem to be (a) a polarity error as I suggested -
possibly introduced due to a meter change - or old 15A MCBs
overheating and thermal tripping.

The polarity error is possible, but it seems hard to believe that none
of the visiting sparks have done a continuity test between L+N and E on
the circuit and the heater (even if they did not do a full insulation
resistance test).


I don't think it is a polarity error, it has to be thermal operation of
the E7 board oldish MCB(s). Try replacing the MCB for the heater circuit
that is tripping.

On 21/12/2017 15:20, Ash Burton wrote:
On 20/12/2017 12:06, John Rumm wrote:
On 20/12/2017 10:32, wrote:
On Tuesday, 19 December 2017 17:44:05 UTC, Steve Poulton wrote:
Please help. I have a basic understanding of electirics, but 5
Electricians
are stumped and I don't know where to go next.
for full context, visit
https://www.homeownershub.com/uk-diy...t-1257719-.htm


There's even more context at

https://www.electriciansforums.co.uk...ircuit.124737/


So far possibilities seem to be (a) a polarity error as I suggested -
possibly introduced due to a meter change - or old 15A MCBs
overheating and thermal tripping.

The polarity error is possible, but it seems hard to believe that none
of the visiting sparks have done a continuity test between L+N and E
on the circuit and the heater (even if they did not do a full
insulation resistance test).


I don't think it is a polarity error, it has to be thermal operation of
the E7 board oldish MCB(s). Try replacing the MCB for the heater circuit
that is tripping.

That would only make sense if the new heater is more powerful than any
of the others, since the trip moves with the heater to other MCBs.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 22/12/2017 03:39, John Rumm wrote:
On 21/12/2017 15:20, Ash Burton wrote:
On 20/12/2017 12:06, John Rumm wrote:
On 20/12/2017 10:32, wrote:
On Tuesday, 19 December 2017 17:44:05 UTC, Steve PoultonÂ* wrote:
Please help. I have a basic understanding of electirics, but 5
Electricians
are stumped and I don't know where to go next.
for full context, visit
https://www.homeownershub.com/uk-diy...t-1257719-.htm



There's even more context at

https://www.electriciansforums.co.uk...ircuit.124737/



So far possibilities seem to be (a) a polarity error as I suggested -
possibly introduced due to a meter change - or old 15A MCBs
overheating and thermal tripping.

The polarity error is possible, but it seems hard to believe that none
of the visiting sparks have done a continuity test between L+N and E
on the circuit and the heater (even if they did not do a full
insulation resistance test).


I don't think it is a polarity error, it has to be thermal operation of
the E7 board oldish MCB(s). Try replacing the MCB for the heater circuit
that is tripping.

That would only make sense if the new heater is more powerful than any
of the others, since the trip moves with the heater to other MCBs.


The OP said "The largest of the Night Storage Heaters began to fail and
trip the MCD." So, I assume the replacement is also large.

These heaters are expensive items, so replacing one that was possibly
working okay is a shame.

On 22/12/2017 03:39, John Rumm wrote:
On 21/12/2017 15:20, Ash Burton wrote:
On 20/12/2017 12:06, John Rumm wrote:
On 20/12/2017 10:32, wrote:
On Tuesday, 19 December 2017 17:44:05 UTC, Steve PoultonÂ* wrote:
Please help. I have a basic understanding of electirics, but 5
Electricians
are stumped and I don't know where to go next.
for full context, visit
https://www.homeownershub.com/uk-diy...t-1257719-.htm



There's even more context at

https://www.electriciansforums.co.uk...ircuit.124737/



So far possibilities seem to be (a) a polarity error as I suggested -
possibly introduced due to a meter change - or old 15A MCBs
overheating and thermal tripping.

The polarity error is possible, but it seems hard to believe that none
of the visiting sparks have done a continuity test between L+N and E
on the circuit and the heater (even if they did not do a full
insulation resistance test).


I don't think it is a polarity error, it has to be thermal operation of
the E7 board oldish MCB(s). Try replacing the MCB for the heater circuit
that is tripping.

That would only make sense if the new heater is more powerful than any
of the others, since the trip moves with the heater to other MCBs.

But does not trip when connected to an mcb on the 24 hr supply board IIRC.

On Friday, 22 December 2017 09:55:43 UTC, GB wrote:
These heaters are expensive items, so replacing one that was possibly
working okay is a shame.

Especially when the fault turned out to be arcing within the off-peak CU main switch

Owain