ELCB Tripping

roker

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About every 2 or 3 months I get a ELCB trip.
it's gone off in the middle of the night when no one is using anything. or randomly during the day and resets no problem.
Any Ideas where to start with this I realise that any circuit or appliance if left plugged in can trip the system by touching neutral
and earth even if they are switched off
 
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I realise that any circuit or appliance if left plugged in can trip the system even if they are switched off by touching neutral to earth

Ok, not exactly correct, but that's for another day.

If it is only tripping that intermittently it is going to be nigh on impossible to trace a faulty circuit, if indeed it is a faulty circuit causing it.
If it were me ( well to be perfectly honest I could test the ELCB but....) I would just swap out the old one with a new one and wait a few months. :)
 
thanks sparkRite, I will try a new ELCB
The house is 10yr old, I have found that the downstairs sockets require me to switch off 2 mcb to isolate 1 circuit, making me believe that 2 of the return ring main is crossed, but I don't think that would cause a trip problem
 
I have found that the downstairs sockets require me to switch off 2 mcb to isolate 1 circuit
Really gets my goat that one! The amount of times I have seen that :mad:, entirely down to carelessness by the electrician ( title used in it's loosest sense ) terminating the board! I advise that you address that ASAP.
Either split the circuit into two separate radials or close the ring correctly on one MCB.


I don't think that would cause a trip problem
Correct, certainly not an intermittent one. The usual suspects (enjoyed that movie) of night 'nuisance tripping' are 'fridges and freezers.
 
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SparkRite beat me to it, Fridges and freezers , or anything that comes on intermittently. In my case it was the septic tank pump. Took a while to track down.
 
SparkRite beat me to it, Fridges and freezers , or anything that comes on intermittently. In my case it was the septic tank pump. Took a while to track down.
:D :D

Yep, pumps as well, but I'd give odds that it was tripping more often that once every few months.?
 
I had a similar issue in our house a few years ago, turned out to be the microwave! It would trip at all sorts of time, unrelated to usage. Took it to a repair place and they replaced some sort of door safety switch.

As others said, something so intermittent is going to be very hard to isolate, but for appliances that can be left plugged out and only plugged in when needed (eg kettle, microwave, toaster, washing machine, dishwasher, TV), you could try leaving one out at a time. Each time you continue to get a trip you'll at least have ruled something out.

If it's really wrecking your head you could take SparkRite's advice to get that circuit breaker issue resolved, but while the electrician is there have them replace the ELCB with RCDs on individual circuits. Might help you narrow down the cause, but also means if you have trips in future for other reasons only part of the house gets tripped. Particularly handy if you're on holidays and perhaps the immersion will trip it, but the freezer gets to keep operating for example.
 
Thanks all, one thing to note is there are so many small power packs plugged in around the house for mobile phones, cordless phones, electric clocks, modems, even TVs and satellite boxes. I stand corrected but if 2 or more appliances have a small leak they could total up to make the full 30mA trip limit
 
but while the electrician is there have them replace the ELCB with RCDs on individual circuits.
Yes I agree to a certain point, as ELCBs are 'old hat' these days, but in this case, it may be akin to 'using a sledgehammer to crack a nut'.

Changing it for separate RCBOs (NB.:- * see below) may well stop the extremely sporadic tripping if the ELCB was to blame in the first place and/or will prove which circuit the earth leakage is on, if indeed there is one at all.
All very good, but comes at a price that may not have been necessary, hence the sledgehammer analogy.
I'm not saying the ELCB is faulty but it is a good place to start in this instance and may well turn out to be cheap and easy fix.

*
RCDs (residual current device) have no overload protection and have to be used along with (usually) an MCB.
RCcBOs, generally the second 'c' is dropped so becomes RCBO (residual current circuit breakers with overload) have both overload and earth leakage protection.
I'm not being pedantic, it is an important distinction.
 
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Thanks all, one thing to note is there are so many small power packs plugged in around the house for mobile phones, cordless phones, electric clocks, modems, even TVs and satellite boxes.
Phone chargers usually employ 'double insulation et al' and are not earthed.
Ditto for modern TVs (used to be used as a means of reducing induced harmonics among other unwanted 'noise') but usually not for sat boxes that have inbuilt PSUs ie. these would use the earth conductor.

I stand corrected but if 2 or more appliances have a small leak they could total up to make the full 30mA trip limit
You can stay sitting down, that is correct. :)
 
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Yep, pumps as well, but I'd give odds that it was tripping more often that once every few months.?
Nope, as our peculation area is slightly higher than the septic tank (don't ask), the pump was triggered to pump up to the peculation area when the 2nd chamber of the septic tank reached the float switch level. Standard greywater pump with float switch.

once it failed/leaked it would randomly trip the switch. Happened every few days/nights
 
one last point I assumed it was an ELCB it could be a RCB on looking at it, it has the letters BPC?
 
Post a close up pic and I'll have a look.
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Yep, its an RCD, does the same job as an ELCB, neither have overload protection though.
Main difference is in how the imbalance is detected, ELCB uses voltage within a field coil while an RCD uses current.
 
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