Any electricians in the house?!

After a bit if advice as I’m stumped on this one… Basically the dishwasher has been tripping the MCB on the consumer unit. Tends to happen later on into the 2 hr cycle but hard to say for definite it’s always at the same point in the cycle. The RCD doesn’t trip only the one MCB.

Anyway, I’d assumed it was a faulty dishwasher maybe causing an earth. Before pressing the buy button on a new machine I thought I’d quickly try it again with an extension lead to a socket in the conservatory (different circuit)…worked fine. So, tried the extension lead again but this time to a differentsocket in the kitchen (same circuit)…again, worked fine with no tripping. Straight away I’m thinking maybe there is an issue with the socket the dishwasher is usually plugged into? However, having tried a few small appliances (kettle, toaster etc) in that socket they seem fine…so, any ideas?! Is it worth having a go with one of those 13A socket testers? Cheers!

not much point in a socket tester tbh, circuit should have been checked on install.

if rcd does not trip it shouldn’t be an earth fault

sounds hard to tell if a socket fault or dishwasher fault.

I’d try dishwasher in alternative locations if possible, if you are sure fault is not with kitchen circuit then get new dishwasher – if not get sparky in to fault kitchen!

Works fine both on a different circuit, and a different socket on the same kitchen circuit…

Dishwasher socket in a stupid place like under the kitchen sink ??

Sounds like the socket or wiring (may be something to do with increased load) to that socket is at fault. The dishwasher works fine on a different socket and circuit so surely it can only be that particular socket. I think replacing the socket is cheaper than a new dishwasher?

Does it trip every time or occasionally? If not every time then run the extension lead tests a sufficient number of times to ensure that the non-fail result isn’t a fluke.

Try the extension lead on the same socket the washing machine is normally plugged into. Does it fail on that?

Also, take the socket off and check there isn’t reverse polarity.

Is this a recent issue or has something been done to the circuit/socket recently to potentially cause a problem?

I would not expect the dishwasher to fail at the same point every time if it’s a broken or faulty socket. It is more likely to happen randomly in the cycle and also with other appliances.

The RCD should pick up an earth fault before the MCB but if the RCD is faulty the MCB will trip if the fault current is big enough.

Rich.

Yep, I’m just running it again now using a different socket in the kitchen (same circuit) for the second time. If it’s ok then I’ll assume the machine is fine & try replacing the socket it’s normally plugged into. I’ll try taking the face plate off first to check for any loose bits etc.Just very strange that other electrical bits work fine on that socket, maybe it’s due to the increased load of the dishwasher compared to say a kettle, toaster etc?

If it was an Earth fault at the socket the RCD should trip (if the RCD is faulty you need to get it changed)

An MCB trip points to an Over-current event, however MCBs overtime can become more sensitive leading to spurious tripping, Id try a new MCB before a new machine. Alternatively the washing machine may be drawing more current than it should. How old is it? Does the three pin plug have a metal earth pin?

I do hear what you say about it being on the same circuit when you tried it from another socket, my guess would be something else wasn’t the same. Maybe you’d unplugged a 3kW heater to test it:)? Alternatively and it sounds unlikely but the extension if it was long enough could have added enough resistance to cause a volt drop at the washing machine under load, which could have limited the current to a small degree. But again seems unlikely.

The dishwasher load is no more than 3kW for the element. The motor will likely have a high inrush current but that should not be such that it would cause a normal “B” curve MCB to trip.

I’d be looking to run more than 2 cycles on a different socket and circuit to be beyond reasonable doubt it’s not machine related. Depends somewhat on frequency of tripping but I’d go for 10 cycles.

Just very strange that other electrical bits work fine on that socket, maybe it’s due to the increased load of the dishwasher compared to say a kettle, toaster etc?

Different devices present a different kind of load and one might cause a socket issue to show up and the other not.

Possibly a bit of progress…I noticed earlier a sizeable puddle of water below the water inlet. This was also dribbling slowly down the electric cable from the suspect socket. So, gave the area a good dry out and re secured the inlet using some plumbers tape for extra watertightness. So far so good. Dry as a bone. Just run a full cycle and nothing’s tripped….fingers crossed for another go later!