Any ideas? About 1 hr into the cycle, or 10min after finishing if using the shorter cycle, the RCD trips. This happens even if we have turned the dishwasher off at the mains. It then carries on tripping the RCD non stop for about 15 – 30mins.

Dishwasher is a 3 year old Bosch. I’m wondering if this is the sort of thing that is repairable for a sensible cost or if I should save the money of a callout and just buy a new dishwasher.

get your rcd tested sometimes they can get very sensitive and trip at a very low earth leakage value anything less that 21m amps and its buggered
also test the tripping at half and full trip current

Sounds to me like a rcd issue but next time it happens try unplugging the dish washer and then reset the RCD because there may be a neutral earth fault with the dish washer

I had this a few years ago, I swapped the plug on the dishwasher (it was a moulded one) and the problem was resolved. I’m no electrician though, just letting you know what worked for me.

Could it be condensation building up during the cycle resulting in earth leakage somewhere.

also test the tripping at half and full trip current

What does that mean and how do I do it? Also, can I test the RCD myself for faults or is that an expert job?

Thanks

when you test an RCD, you test test it at the full rating and 5 times the rating which it should trip with 40ms then at half the rating at which it shouldn’t trip.
You fault sounds like the machine is at fault, but try isolating all other equipment and see if the fault persists, sometimes the combined earth leakage of other equipment can be the issue with the washing machine being the straw to break the camels back!

you need an RCD tester to carry out the tests

definitely the dishwasher, it still happens when everything else is switched off. Seems odd to me though that it still happens after it is turned off at the wall.

Condensation / steam build up makes sense as seems to happen at the same point in the cycle, if this is the case is it likely to be repairable or should I just get a new machine?

The switch probably only isolates Live whereas an RCD will still trip with a Neutral / Earth short.

Personally I’d inspect the wiring in the plug / socket / switch to check for a loose wire. If they all look fine, it could be a fault in the dishwasher. You could swap out the RCD but that’s not a trivial job unless you have a master isolation switch in front of the consumer unit (otherwise you have to do it live).

Some sockets outlets are only single pole so don’t isolate the neutral, better ones are double pole. You have a single pole. The dishwasher has a neutral to earth fault somewhere but it’s impossible to tell where remotely. It sounds like it may be a breakdown of the insulation when the machine gets warm. The insulation only needs to ‘thin’ to allow the 30 mA through to trip the RCD, they’re very sensitive. You could get the RCD tested but it’s not cheap, and a ramp test should be performed too to see the actual tripping current, this is usually around 28mA. The testers are £280 in Screwfix (KewTech) so not something you’d do yourself, and you’d be better saving the money and putting it towards a repair/replacement of the dishwasher. It’s usually something fairly simple such as a wire touching something it shouldn’t be, they’re usually held in clips but can work lose.

I would guess a small leak somewhere getting into some electrical stuff. It then dries out so it’s ready to go again. Unplug it and open it up to have a nose around to look for leaks if you like that sort of thing.

I had a Bosch dishwasher out of warranty that did exactly this. Firstly make sure the tray underneath the washer is empty – you can tilt the washer, but get ready for the deluge. If you are lucky it could just be this causing water to get in the electrics underneath (I think its the heater).

In my case it wasn’t and I thought that I would pay for Bosch service engineer. It was a fiasco really. Several visits all replacing different bits all to no avail. In the end I complained so much that they sold me a new one half price.

Soo, update for all of you dishwasher fans.

I pulled out the machine tonight, undid some screws, took some panels off and prodded about.

Tray underneath is dry as a bone, no damage to plug or cable and everything looks fine, except… The back panel of the machine is covered in a black tar like panel, assume it is some sort of insulation. A section of this has melted, you can literally see where it dripped from overheating Now, I am not an expert, but that doesn’t seem right, does it?

I suggest you stop using it – either get someone in who knows what they are doing with dishwashers or replace it. Before it goes up in flames 🙂

Whats in the vacinity of the over heated melted area ?

No, that doesn’t seem right. Replace it as it’s simply not worth the risk. Be quick too, before the EU ban them (mark my words, it’s coming).
CD

I had this problem o na Hotpoint one, it was going through the pre-wash cycle, then popping the circuit breaker. I figured out it was the heater element, it was switching on after about 40 minutes to heat the water after the prewash cycle and immediately tripping the RCB. I changed it for a new one and the problem was solved.
Might not be your problem but it sounds similar. You can test the element with a multimeter or suchlike.

We’ve had this problem with a Bosch also …But it only tripped the circuit once when the heater element failed…

My RCD kept tripping every so often, couldnt figure out which appliance was doing it. In the end I got an electrician out. This is what he found 😯

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Obviously this made the wife correct for phoning an electrician and me wrong for almost killing everyone, by not ringing earlier..

get someone in who knows what they are doing with dishwashers

Phone the dishwasher “engineer”.

Long overdue update: We got a new fridge!

Electrical appliance engineer came out and couldn’t find any thing wrong with dishwasher. The heat damage on the back is common, it happen where the waste pipe is contacting the meltable plastic on the back of the appliance

Electrician came out and spent three hours testing sockets, RCD and just about everthing else. Was about to pull walls apart to visually check wiring when he randonmly decided to test the fridge. Turns out the compressor was faulty and when it was working hard it was blowing the RCD. So, when the dishwasher got really hot, the heat was being sent around the back of the fridge, compressor would kick in and RCD would blow.

So, new fridge delivered next day from AO.com, improved ventilation for dishwasher and been sorted ever since.