rcd tripping

[TOMMY THE CAT]

Right woke up to no sockets trip was down, put it back on tripped out doh!
Straight away thought the only load on in the early hours was the combi.
Sime 80e friendly (huh!) format bout 5 years old.
Weird deffo the boiler checked the spur fuse etc. Looked at the timer clock which stopped when it tripped and the boiler was at standby no heating or hot water called for? (3.30 am) Anyway had a look see at the panel turned the boiler on to off turned it on again after checking the terminals are tight and hey presto works again dhw and ch???
3 hours later heating etc off chucks the rcd at the mains on the sockets again. Just turned it on now and everything is fine.....was thinking the on/off/winter /summer switch neutral problem??? Anyway just wanted to know the best place to start looking for the fault... I have the wiring diagram.Ta D

 

[JohnD]

look first for a water leak dripping onto the pcb or connections.

Also could be the pump leaking into the motor.
You may see signs of water damage.

Boilers sometimes drip when cold but not when hot due to expansion movement plus evaporation before the drip forms.

Try turning off the electric supply at the FCU to check if that stops it tripping.

 

[Paul Barker]

Yes, anyway boiler fixed appliance doesn't need to be on the rcd side.

If it's on same supply as kitchen ring then it could be amalgamation of the emi filters causing leakage on washing machine microwave and dishwasher, added together this causes tripping.

Combine that with a steamed up kettle and bang, your rcd has tripped.

Last kitchen ring I put in, I put the cooker supply on the non rcd side with a socket in the cooker switch and printed (on my nice professional printer) a lable saying not for outside use. Into this could be put the kettle and the microwave.

Another sugestion is to put the fixed appliances on fused spurs with roundwire outlets behind them and switch above. All on non rcd side.

Never put lights on the rcd.

Of course if you have a TT earth you must put everything through 100ma rcd but these nuicance trips may not occur at 100ma in any case.

A 30mA rcd will normally trip at 15 to 20ma's in any event.

 

[Shivering Code Monkey]

I had this happen with my boiler a couple of years ago. It took me some time to work out that it was the boiler tripping the rcd. It was the DHW switch. The gland for the shaft operating the microswitch had started to leak and since this was likely to happen it had been positioned directly above the mains terminal block. Brilliant. A new diaphram switch assembly sorted it.
Good luck.

 

[TOMMY THE CAT]

Thanks for the replies guys I think a leak certainly could be the answer as I have seem to be loosing pressure on the dial. Pressumably the best way to look for the said leak is when the unit is cold as mentioned? I take it it could be a very small drip as I havent noticed any obvious water patches?
Also on this subject my friend has got a combi in a caravan and he does have to top it up with the valve as he looses pressure on his......... could this be a leak? Radiator etc? What pressure loss is normal over time? Should he be adding any additives to the sytem if he has been diluting the rads etc? (I'm making his sound worse that it is it is only periodic refilling.)
Thanks for your help in advance Dave.

 

[baxpoti]

Never put lights on the rcd.

Unless there in Zone 1 of a bathroom.

 

[ChrisR]

Normal loss is a bar or so in several months, which makes me a lot of dosh, with tenants screaming no ch or hw, and an emergency 2 minute call. Unfortunately quite a lot go over the year...

If you have a way(proper drain cock) to let water OUT, you can put the pressure up to 2.5 bar or so to look for leaks. Don't run the boiler with it at that - let the pressure back to 1 - 1.5 bar.

I recently bought a 1mA clamp meter specifically to look for earth leakage currents, yet to use it in anger. (Maplin, under £30)