Earth leakage circuit breaker.

andicole0

andicole0

andicole0

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Any qualified electricians here? This seems to trip randomly every few weeks same things plugged in and it will reset, sometimes after a few minutes. But then it will go for days if not weeks with the same things on.
It is a 30mA trip and was changed about 5 years ago for doing the same thing. Only started tripping in the last few weeks. Do these things age? Should I have a different spec unit?
Electrician coming Monday.
Andi.
 
andicole0 said:
Any qualified electricians here? This seems to trip randomly every few weeks same things plugged in and it will reset, sometimes after a few minutes. But then it will go for days if not weeks with the same things on.
It is a 30mA trip and was changed about 5 years ago for doing the same thing. Only started tripping in the last few weeks. Do these things age? Should I have a different spec unit?
Electrician coming Monday.
Andi.
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What do you have plugged into the circuit? (Fridges/Freezers perhaps?)
 
andicole0 said:
Yes usual household stuff. Nothing changes at the point of tripping.
Andi.
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While I am not entirely sure what is going on, It is my experience over the years that equipment with induction motors in it (Fridges and freezers in particular) can occasionally trip ELCB's even where there is nothing otherwise obviously wrong with it.

I am sure I recall advice from many years ago that fridges and freezers should not be plugged into ELCB protected supplies.
 
Ok some additional info. When it does trip the earth leakage sometimes turning it back on trips the Ring Main 2 fuse (upstairs sockets) but again after a minute or so it will all reset.
With this on mind I have avoided one particular socket and, touch wood, it has been ok with hoovers, saws and extension leads upstairs.
Andi.
 
Will either be a faulty RCD (Unlikely) or a faulty circuit/Appliance. Anything that has a heating element in it or in contact with water is the usual suspect. The electrician should be able to identify it easily.
 
The suspicious socket looks like it is the point at which power to the loft is taken. CCTV and a nas on a ups are up there but been running 24/7. Hopefully leccy man can do his magic.
Andi.
 
Orionaut said:
I am sure I recall advice from many years ago that fridges and freezers should not be plugged into ELCB protected supplies.
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That advice is more to do with nuisance tripping on other circuits which will in turn mean you could loose your food in the fridge/freezer.
This is what high integrity consumer units were developed for, so that you can have a normal split load board with the RCDs protecting the required circuit(s) and then separate RCBOs for essential circuits - fridge/freezers etc. Unfortunately not many people fit them or end up with the expensive alternative of RCBOs for every circuit.


As above though, sounds like an appliance going faulty.
 
mattyy said:
That advice is more to do with nuisance tripping on other circuits which will in turn mean you could loose your food in the fridge/freezer.
This is what high integrity consumer units were developed for, so that you can have a normal split load board with the RCD's protecting the required circuit(s) and then separate RCBOs for essential circuits - fridge/freezers etc. Unfortunately not many people fit them or end up with the expensive alternative of RCBOs for every circuit.


As above though, sounds like an appliance going faulty.
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I always though the advise was two fold. Both what I said and what you said.

IE Induction motor gear does occasionally trip RCB's AND you do not want to come back after a weeks holiday to find a freezer full of rotten food.

Thinking about it a bit more. Modern circuit breakers are much more sensitive than traditional wire fuses. Induction motors will typically generate a brief surge many times normal running load. This is what is likely to be generating random trips rather than internal earth leakage faults. So yes, Induction motors can be a problem for modern circuit breakers of all sorts. But perhaps the RCB's are more sensitive than MCB's and therefore more vulnerable to surge tripping

(It is a long time since I did any I^2t stuff, I will have to look it up sometime)

Most appliances like vacuum cleaners and washing machines use universal motors or inverter driven motors where this is less of an issue.
 
Orionaut said:
I always though the advise was two fold. Both what I said and what you said.

IE Induction motor gear does occasionally trip RCB's AND you do not want to come back after a weeks holiday to find a freezer full of rotten food.

Thinking about it a bit more. Modern circuit breakers are much more sensitive than traditional wire fuses. Induction motors will typically generate a brief surge many times normal running load. This is what is likely to be generating random trips rather than internal earth leakage faults. So yes, Induction motors can be a problem for modern circuit breakers of all sorts. But perhaps the RCB's are more sensitive than MCB's and therefore more vulnerable to surge tripping

(It is a long time since I did any I^2t stuff, I will have to look it up sometime)

Most appliances like vacuum cleaners and washing machines use universal motors or inverter driven motors where this is less of an issue.
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There is more to it than what you are thinking. An induction motor should not be tripping an RCD - if you have earth leakage at the amount to trip a correctly rated RCD then it is a fault with the motor/cable/component.
A brief surge in running load, ie the starting current will also not trip an RCD - it would trip an incorrectly rated (either by current rating or ramp type) MCB or if there is a fault with the motor and it is pulling more current than originally designed.
What you have described is a motor that is now either leaking current to earth or pulling more current than originally designed and is clearly developing a fault.

I would not imagine that the advice would be two fold either - I would not want to buy a fridge/freezer on the basis that it may randomly and unknowing trip at random intervals because the design was incorrect. I would also not care if my faulty fridge/freezer tripped my Television etc as it is not an essential piece of equipment.

IE Induction motor gear does occasionally trip RCB's AND you do not want to come back after a weeks holiday to find a freezer full of rotten food.
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How would you solve that if it was true that it was a flaw with the piece of equipment you want to save? Hence why you put the fridge/freezer on a separate circuit (for the reasons I have stated). Nothing will trip the fridge/freezer except for itself.
 
andicole0 said:
Ok so it looks like smart power adapters leak a little as does a dodgy ups. Only time will tell.
Andi.
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Any electronic will naturally leak to earth, but it's a cumulative effect on the RCD either through multiple appliances (Think PCs, Monitors in Office Blocks) or faulty kit in Domestics (Leaking more current to earth). There are fancy ways to direct it away from the protective device but not for your home.

You can get your appliances PAT tested to identify if they are on the way out.
 
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