Nuisance trips

[blondini]

Had a few nuisance trips of the earth leakage breaker lately. Getting slowly worse, and I'm starting to spot a pattern. It seems most likely to happen when just starting an appliance like a microwave or a power tool, but randomly and not every time. It's only stuff connected to the downstairs ring that's doing it, but then the upstairs ring only has a few table lamps on it anyway.

Should I be looking for a circuit fault, or could the breaker be to blame?

 

[JohnD]

I would suspect that you may have background leakage, and the extra appliance is not the real trouble, just the last straw.

Start by unplugging the washing machine, dishwasher, kettle and any other "watery" appliances.

Presumably you have no outdoor sockets or lamps on the ring that could be damp?

Do you have a suspended ground floor, with cables that rodents might be gnawing at?

 

[sparky40]

I would get rid of the voltage operated earth leakage circuit breaker altogethery as they are not recognised anymore as a protective device. In my opinion you would be best off doing an earth fault loop test on the circuit, otherwise a qualified spark could fit a rcbo instead of a circuit breaker, ( might hold in as they have wider parameters.). Certain breakers, type c+d are bettter if you have high 'in rush' of current and wont trip like a type b. Best to get a spark in and get it tested as it could be a variety of things.Hope this is of some help.

 

[JohnD]

I would get rid of the voltage operated ....

Is it one?

If it's an RCD that's tripping I don't see that "C" or "D" MCBs are relevant.

 

[sparky40]

Sorry, did not explain myself. I meant if mcb's were to fitted in a new cu. If a voltage operated elcb was being used at present I would replace it.

 

[blondini]

Thanks for the replies everyone.
Yes I think there may well be a bit of background leakage, I'll look into it.
I do have suspended floors and the occasional mouse has managed to find it's way in before.

 

[securespark]

You need to do a ramp test on the RCD. This will tell you at what current the unit is tripping. 15mA is a definate fail. I like to see min 18mA.

Do this test at the RCD in isolation, not from a circuit attached to the RCD.

Then do the same test from a socket outlet. You may well find the result lower, especially if some appliances are running at the time.

The difference can be seen as earth leakage in the system.

 

[JohnD]

You need to do a ramp test on the RCD.

True, but what should the sensible householder do who is not lucky enough to have an RCD tester?



Mr Blondini, out of interest, what are the numbers and letters on your RCD/ELCB?

 

[plugwash]

surely all you need is a 2K mains rated potentiometer and a multimeter.

then just turn the current up until it trips and measure the resistance of the pot afterwards. its simple calculations from there.

 

[JohnD]

Speaking as a hypothetically sensible housholder, I don't think I'd rely on half-remembered O level physics and my clumsy breadboarding skills to assemble a test rig and use it safely.









Fortunately I'm one of the lucky few.