Intermittent Electricity

Username03725

Weird one this. The dishwasher stopped a couple of months ago, failing to finish the overnight cycle. Checked the RCD at the CU, checked supply voltage at the wall, checked fuse on wall switch above desktop - all good. The dishwasher then worked for a couple of nights then failed again with the same issue - completely dead halfway through its cycle, so I assumed an end of life dishwasher and got & installed a new one.

Now the one is doing the same - it stops during the cycle and is to all intents & purposes electrically dead. Switching it off for a while then back on at the fused switch above the worktop restores life, and it all works again. 

How so? There's no obvious break in the supply, the power cord to the wall is new (not a leftover from the original) and the connections look good. What could cause the mains supply to be interrupted?

Robin9

Have you tried using the dishwasher at other times ?

Vitor

 - Switching it off for a while then back on at the fused switch above the worktop restores life - 

Could be loose connections. The dishwasher draws significant current during heating cycles, which can cause loose connections to heat up and lose contact. With mains power off, check the wires are held tight on the fused spur. A new fused spur switch costs a few pounds and could eliminate the problem if it's a switch fault.

Frozen_up_north

Is the supply really being interrupted? A common way to tell is if the clock on the microwave, or cooker, shows “8888” or flashes, etc.

Can you temporarily run it from another socket using an extension lead?

The socket may be worn, or have screws that need tightening.

Heedtheadvice

Vitor and Frozen's suggestion are quite likely. If you are competent to play with leccy that is the first place to start.

Beware running from an extension lead if it does not have spec for sufficient current  (over 12 amps) or is not fully uncoiled as it may well overheat.

Newcad

Why suspect the mains supply if nothing else is affected? I'm sure you'd mention anything else.

If it's a particular appliance being affected then suspect that applience is faulty, or If it's a particular type of appliance and it's still happening after replacement then suspect how it is being used.

As it's apparently happened with 2 diffrent machines you can probably rule out a machine fault eg. overheating (although it still may be).

A common cause of diswashers tripping out is the water outlet getting clogged, meaning it can't empty quickly enough so switches off rather than letting more water in and flooding the place. A Power off/on would reset it.

So double check what is being put in there, (are young kids loading it perhaps?), is there too much food waste? large pieces that could clog the drain? Ditto for lots of small bits like rice that can form clumps.
(I once saw one where the drain was clogged by paper napkins that had been underneath the plates, and have heard of similar temporary blockage problems with tea bags. I've even heard of lettuce leaves clogging the drain).

Check your user manual for a list of Don'ts, and for what to look for in the event that it stops running.

sheenas

Try as a test another socket and see if the same happens 

Username03725

Thanks for the suggestions folks. Much appreciated.

It looks like a loose connection in the wall switch above the worktop. I removed it from the wall by undoing the 2 screws whilst the power was still on to have a look and although it all looks ok, when I replaced it the dishwasher had gone through a power cycle, shown by the fact that it was lit up like a Christmas tree on the control panel in the way that it does when first powered up. At a convenient point I'll kill the power and resolve it properly. Well spotted Vitor, looks like that is the issue.

Running it from another socket isn't feasible. It's hardwired into the wall plate under the worktop and fixed in place so it would be a major task to do that. Good suggestion though, if it were freestanding & plugged into a 13A socket outlet.

Newcad - again thanks but any issues arising from use of the device were unlikely given that it's fault state was to be electrically dead. Drainage & blockage issues would generate error messages or beeps and this one sends messages to my phone when the rinse aid or salt is low, so I'd hope it tells me when it's blocked. 

Username03725

It was the fused spur switch at fault. It had deteriorated to not working at all unless the switch was held in a very specific position, when power would flow if it was held just so. New one fitted, all good. The old one on closer inspection had badly pitted contacts on both of the switch contact faces. Binned it, its replacement was £3.99 - not worth not trying as the first option, and that fixed it.

Heedtheadvice

Grand. A simple fix.