Crazy RCD tripping

[Toddzbox]

Here's my problem: I hope I've isolated the appliance that causes the right hand side of our consumer unit RCD to trip.
If we leave the dishwasher on alone we can come home to find the CU has tripped. I flip off the offending circuit (washing machine, tumble dryer, heating boiler, dishwasher) and can the the rest back on.
To me, that's the easy bit! What I can't understand that after a freezing cold evening and night I can get up early next morning and can then, and only then flip the offending circuit back on, the heating comes on and all's well again?
I do take all the plugs out of the appropriate sockets when this happens, the boiler man has serviced and come back to check the boiler.
It has been about 9 days since the last time it happened - another reason I can't work out what to do next.
Any suggestions on how to proceed? Obviously call out a domestic electrician but we're oldish and poor and this seems to be one of those expensive to find problems.

 

[JohnW2]

Here's my problem: I hope I've isolated the appliance that causes the right hand side of our consumer unit RCD to trip. If we leave the dishwasher on alone we can come home to find the CU has tripped. I flip off the offending circuit (washing machine, tumble dryer, heating boiler, dishwasher) and can the the rest back on.

Welcome to the forum.

Are you saying that if you don't switch off that circuit, you cannot (immediately) re-set the RCD? If so, what happens if you unplug the dishwasher - can you then re-sent the RCD?

To me, that's the easy bit! What I can't understand that after a freezing cold evening and night I can get up early next morning and can then, and only then flip the offending circuit back on, the heating comes on and all's well again?

Well, if the cause of the fault is intermittent (e.g. water getting into the electrics of your dishwasher), then that problem would probably eventually go away (e.g. due to the water ingress 'drying out').

As you have surmised, finding the cause of this sort of problem can sometimes be difficult/tedious, not the least because of its intermittent nature. If you have good reason to suspect the dishwasher, one think you could do (if you're prepared to do without the DW, and get your Marigolds out!) would be to leave the dishwasher unplugged for a good while and see if any further RCD trips occur.

Kind Regards, John

 

[Toddzbox]

That's food for thank you. Not being keen on marigolds we have been using the dishwasher via an extension lead. This generally works - certainly better than plugged into the behind the kitchen unit near the kitchen sink socket! I shall have good think and root around.

 

[JohnW2]

That's food for thank you. Not being keen on marigolds we have been using the dishwasher via an extension lead. This generally works - certainly better than plugged into the behind the kitchen unit near the kitchen sink socket! I shall have good think and root around.

If you are successfully using it (without trips) (and continue to be able to use it without trips) by running it via an extension lead from another RCD-protected circuit, then that would obviously let the dishwasher off the hook as being the culprit.

Kind Regards, John

 

[AndyPRK]

is the boiler on the same circuit/mcb as the boiler ?

 

[Toddzbox]

Well it's gone twice using the lead, but I take your point, and check my facts.
The only thing running when we left today was the dishwasher. But you're right.

 

[Toddzbox]

is the boiler on the same circuit/mcb as the boiler ?

If you meant to say Dishwasher Andy, yes. As a non electrician we haven't ever had the tumble drier, dishwasher, washing machine and heating on at the same time cos it seems too much power for one circuit to me.

 

[JohnW2]

As a non electrician we haven't ever had the tumble drier, dishwasher, washing machine and heating on at the same time cos it seems too much power for one circuit to me.

Even if it were, that would, of course, not be a reason for an RCD to trip.

The 'heating' (if you mean boiler + pump etc.) will use little electricity. As for the rest, it's by no means unknown for people to have tumbler dryer, dishwasher and washing machine all running from the same circuit simultaneously, without a problem. In fact, the average consumption of that lot is less than you would probably think. Depending upon the type, the dryer might draw high current continuously, but the DW and WM will only represent a high load whilst heating water - that's only for a relatively short period of time, and often not even simultaneously for the two machines.

Kind Regards, John

 

[JohnW2]

Well it's gone twice using the lead, but I take your point, and check my facts.

Was it plugged into a circuit (via the extension lead) which was protected by the same RCD as it was previously tripping (i.e. it was the same RCD that tripped). If so, would it be possible for you to plug the extension into a circuit protected by the 'other' RCD (presuming, that is, that you have two RCDs!)?

Kind Regards, John

 

[Toddzbox]

The consumer unit has two sides both populated by what I would have called in the old days fuses. The part of the unit to the right is the one causing the RCD to trip.
When using the dishwasher on a lead, it's on a different circuit with another RCD which doesn't trip.
Sorry if I confused you.

 

[JohnW2]

When using the dishwasher on a lead, it's on a different circuit with another RCD which doesn't trip. Sorry if I confused you.

I'm afraid that I am still a bit confused

When you say "...another RCD which doesn't trip" do you mean "...another RCD which usually doesn't trip"? (i.e. which previously was not tripping) - and, if so, when you wrote that "...it's gone twice using the lead...", did you mean that the RCD which doesn't usually trip did trip (twice) when you plugged the DW (using an extension) into a circuit that was protected by it?

If that is what you meant, then that would surely more-or-less prove that the dishwasher was the guilty party, and therefore needed to be repaired or replaced, wouldn't it?

Kind Regards, John

 

[Toddzbox]

To save confusing you again, your previous answer stands in that it can't be the dishwasher.
So I've now unplugged everything I can, except the boiler which is wired into a fused plate.

 

[JohnW2]

To save confusing you again, your previous answer stands in that it can't be the dishwasher.

Well, as you might imagine, I'm still a bit confused. However ...

So I've now unplugged everything I can, except the boiler which is wired into a fused plate.

Fair enough.

If you still get trips, they obviously would have to be due to something you couldn't unplug (like boiler etc.), or even the wiring (including things like 'water in a junction box') - in which case you would probably need professional assistance.

If you get no trips with everything else turned off, then you'll just have to start plugging things back in, one at a time, in the hope that that will identify the culprit.

Kind Regards, John

 

[Toddzbox]

Thanks for all your help John you've helped me move away from one culprit and given me a few more ideas to chase up. Stephen OK