Earth Fault Indicator tripped twice...

[InquisitiveA]

Hi,

I'm not an electrician and my experience is limited to re-wiring a few light fittings.

I recently fitted a new light fitting to the downstairs front room and at the same time fitted a new dimmer switch. Both seem to work fine. Shortly afterwards the earth fault indicator in the fuse box tripped, it did so when the previously mentioned light was switched off and wasn't being touched and it tripped at the point I was switching on another light in the downstairs bathroom. It worried me a bit but the EFI allowed me to switch it back on and all was fine for 48 hours.

Last night, when all lights were off and nothing was being touched, the EFI tripped again. Again it has allowed me to reset it this morning, but having happened twice I'm concerned that it isn't just a random coincidence.

What can I deduce from the above do you think? Does the EFI tripping in the middle of the night when no lights are on help diagnose the problem? What about tripping previously when I turned on a light that isn't the one I fitted? Should I start my investigation at the new light/switch, or the light I was switching on when it first tripped, or somewhere else?

Appreciate your help.

 

[Octopus]

Well, without wishing to sound smart I think you'll need a spark to help you. The changing of the lights may or may not be related - the fact that the RCD tripping when the lights aren't on may or may not be relevant. The next thing you should do is unplug as much as feasible to see if its an appliance causing it. Failing that I'd recommend calling a spark in - where are you located?

 

[telectrix]

as murdoch says. without test gear, it's guesswork. it could be anything from a faulty fridge to a duff RCD (EFI, as you call it), to a wiring fault.

 

[InquisitiveA]

Thanks for the replies. I'm based in Bristol.

I know in theory there could be any number of causes not necessarily linked to the work I've done, I was hoping for some guidance as to the probability of causes.

If the circuit is fine most of the time (like it is now) but has tripped twice, does that mean faulty wiring is unlikely? Surely wiring is either correct or not?

If I hit a light-switch and the light flashes for an instant before the "RCD" trips is that a strong indication that that particular light or switch is at fault?

Also what would you expect it to cost to get an electrician to investigate? Just a rough idea, I know it will vary.

Cheers,

 

[Deleted member 9648]

Tripping RCD's are usually caused by a low insulation resistance to earth,this could be anywhere on your installation...It is worth unplugging appliances and seeing if the fault disappears,but if tripping is occasional this is not really practical. Only a competant electrician with test gear can realistically pin point the fault.It should not take very long to isolate what is causing the tripping...but obviously rectifying it is an unknown quantity from here. Expect a local competant electrician to be able to either rectify the fault or have a clear idea of cost within an hour of arrival.

Edit....try to find a local experienced long standing electrician,fault finding is an art an awful lot of the new kids on the block have not mastered.

 

[telectrix]

a light bulb blowing can cause RCD to trip. quite common.

 

[InquisitiveA]

Thanks, but all bulbs are definitely working fine.

 

[overskilled]

Tripping RCD's are usually caused by a low insulation resistance to earth,this could be anywhere on your installation...It is worth unplugging appliances and seeing if the fault disappears,but if tripping is occasional this is not really practical. Only a competant electrician with test gear can realistically pin point the fault.It should not take very long to isolate what is causing the tripping...but obviously rectifying it is an unknown quantity from here. Expect a local competant electrician to be able to either rectify the fault or have a clear idea of cost within an hour of arrival.

Edit....try to find a local experienced long standing electrician,fault finding is an art an awful lot of the new kids on the block have not mastered.

Agree to a degree.....however have met many "old and bold" sparks whose knowledge and experience can be.....worrying...with methods that can verge on deadly.
If in doubt, get references from previous customers,