Main rcd tripping but none of individual ones

Photoframe55

My main rcd has tripped a couple of times in the night. Normally one of the individual ones will have gone as well, telling me where a fault was ie a blown bulb etc, but its just the main one on its own.    Any ideas? 

TheCyclingProgrammer

It clearly indicates some kind of fault on a circuit somewhere but it’s going to be impossible for anyone to diagnose on here. This definitely calls for an electrician to investigate. 

Ectophile

Usually, the main breaker is an RCD, while the individual ones are MCBs (Miniature Circuit Breakers).  An MCB trips if the circuit is overloaded, or if there's a short circuit.  The RCD trips if it detects electricity leaking to Earth.

I say "usually", because there are various alternatives.  For instance you might have a 100mA RCD up front, with a 30mA RCD for each circuit.

One cause of RCDs tripping is damp in the electrics.  Others include rodent damage, frayed wiring or faulty appliances.  A qualified electrician should have the equipment to track down the fault if you can't work it out for yourself.  But tracing intermittent faults can be extremely difficult.

FreeBear

RCD ?

or MCB ?

If it is the RCD that is constantly tripping, I'd suggest looking at stuff in the garage if you have power out there (or any other outbuilding). Perhaps a washing machine, tumble dryer, or fridge/freezer - The first two should always be switched off at the wall when not in use...

knightstyle

When the RCD trips it is usually because some electric appliance is allowing water to get into electrics, this can be condensation or a leak.  So unplug washing machine, kettle, iron etc and see if it still trips.

Rodders53

RCD is a residual current device that trips if Live and Neutral loads are not in near-perfect balance (equal).  An imbalance assumption is there is a fault to earth - maybe through a person - so saving life by it tripping off the electrical supply.

The other trips are MCB - miniature circuit breaker - and they are over-current protection devices.  These won't trip unless a large current between Live and Neutral (or to earth) flows.  That can happen when incandescent filament light bulbs or heating elements fail and may take both trips out as a consequence.

It may be the RCD is faulty and tripping too soon or at random times.
It may be that you have a lot of devices that are 'leaking' to earth (many devices have radio-frequency interference suppressing circuits that can do that, and is usually perfectly fine).  Too many such devices can cause nuisance tripping, though.
It may be that there is some other gradually-deteriorating cause in the house wiring or appliances that is causing the nuisance tripping.
As others have said damp can cause similar problems.

You probably need an electrician with the suitable test equipment to check out your installation (with a check of the RCD trip current and time first) unless you can identify a faulty appliance as the cause.

TELLIT01

When we had our old fuse box replaced, along with work done to extend the electric into a new conservatory, we had a similar problem.  The electrician had a piece of kit which indicated where the fault was, and once a section of the cable under the floor was replaced there were no further problems.

Photoframe55

To everyone who has taken the time to try to help me out with this, thank you and everything said is being looked into!    👍

Risteard

Rodders53 said:

It may be the RCD is faulty and tripping too soon or at random times.

It won't be - or at least that is extremely improbable.
It will be an Earth fault, which is what RCDs are there to protect against.
Incidentally, "MCBs" have not been called that since the 16th Edition was withdrawn in 2008. They are now designated "circuit breakers".

FreeBear

Risteard said: Incidentally, "MCBs" have not been called that since the 16th Edition was withdrawn in 2008. They are now designated "circuit breakers".

If you would be so kind as to tell the manufacturers and suppliers that... The likes of Schneider Electric

are still calling them Miniature Circuit Breakers or MCBs for short.

Risteard

FreeBear said:

Risteard said: Incidentally, "MCBs" have not been called that since the 16th Edition was withdrawn in 2008. They are now designated "circuit breakers".

If you would be so kind as to tell the manufacturers and suppliers that... The likes of Schneider Electric

are still calling them Miniature Circuit Breakers or MCBs for short.

Wholly irrelevant. BS7671:2018 (and BS7671:2008 before it) recognises no such term.