Hotpoint Wdl520 Heating Coil Short

[brendanclarke]

Hi! I've got a problem with my Hotpoint WDL520 and looking for advice. I recently put in a load of towels (read: heavy, wet) and left it to wash and dry while I went to work. I came back and the machine had flipped a breaker (I think when starting the spin cycle - there was still water in the drum, but not much soap).

I manually released the door lock, turned the socket off, reset the breaker, and turned the socket back on. The program came up fine, I switched it to 'pump out', closed the door, and the breaker flipped again immediately (with the door re-locked).

I had a problem a couple months ago where the motor was causing a short - I had cleaned it out with some compressed air, which seemed to solve it at the time, so I thought it was the motor again, but I disconnected the motor and got the same short.

I reconnected the motor and went through the other connectors, disconnecting and seeing what would reproduce the short and found that if I unplugged the heater coil (pink wire pictured here), the washing machine would run (tested just for a few minutes) without shorting.

I disassembled the dryer enclosure (pictured) and found the coil to be quite wet. I tested the resistance of the heater coil (both with the pink wire connected and disconnected) and got 45 ohms. I'm currently letting it dry to see if this changes.

So - questions. Is this a normal resistance for the heater coil? Should I replace it? If this is normal, is there some other current-limiting component that may have failed that I should look at? If this ends up being an expensive repair, can I wash with the machine with the wire disconnected without causing more damage?

Thanks for any help!

[Whitegoodshelp (Andy)]

The resistance sounds ok but it's not the resistance of the part that's normally involved in tripping electrics, it is leakage of current down to earth. You need an insulation test meter to diagnose an appliance tripping the electrics or fusing, so without one you are limited to unplugging things and assuming when something is unplugged and the tripping stops it is because the part you unplugged is the culprit. Educated guessing can work, and should be reasonably accurate, but some things when unplugged could be taking out more than a specific part from the circuit. So for example, when you disconnect the pink and brown connector you are taking out the dryer heating element but you are also taking out the pink wire and the toc inside that lead. So, if the problem was caused by a short inside that cable and somehow power was leaking to the casing where that metal bracket holds the lead to the casing then you would wrongly blame the heating element.

I think it's pretty unlikely to have a short to earth inside that cable due to the heat resistant covering the wire is encased in, but the point is worth noting. To be 100% sure I would reconnect the wire, undo the metal bracket and pull the wire clear from the casing, and then disconnect the wire from the heater terminal. That way you are 100% disconnecting only the heater.

Another potential flaw in the disconnecting parts to diagnose fusing is that if a part is switched on and off via the neutral circuit instead of the live circuit then power could be running all the way through a part and down the neutral return right back to where it is switched so potentially a short to earth in a wire could be on the neutral side - after the part that has been disconnected. Disconnecting the part would stop the tripping because it also stopped any electricity running through it and then down the neutral circuit.

For anyone unfamiliar with this, most parts have a neutral supply that is always connected to the neutral return in the plug. When the part needs to do its job they send power to it and it runs through the part and down to the neutral. But sometimes they can switch a part on and off on the neutral circuit, so the neutral does not go directly to the neutral in the socket but instead goes to a place where there is a switch between it and the neutral going to the socket. These parts have a live connection all the time and power runs through the part and down the neutral all the way to the switch. The part does not operate because the lack of a neutral return prevents current running though but power can still leak to earth and trip the electrics at any point in the circuit (and can give electric shock too).

An engineer diagnosing this fault would take the wire off the element and test the element directly with his insulation test meter (which puts 500 volts DC) through it. They connect one lead to the element and the other to the metal earth on the washing machine and test for leakage of current. There should be no continuity between either of the element's terminals and earth. As my article linked to above describes, if a leak to earth is big enough it can sometimes be detected with a continuity test meter but detecting nothing with a continuity test meter doesn't mean there is no fault, that's the job of the insulation test meter.

If you left the wire disconnected with the heating section reassembled the washing machine should work fine without the dryer part.