Washing machine trips RCD

[davehere]

Hi, 

My hotpoint wmfug942p keeps tripping the RCD when it does a wash that heats the water. It works fine on a cold rinse. This leads me to believe that the fault is with the element. However when I measure the resistance of the element it reads 30 ohms, which would indicate that the element is not the problem.
 

Any ideas on where to go from here?

 

Thanks,

Dave 

[Whitegoodshelp (Andy)]

Hello Dave. No that just indicates that there is continuity through the heating element. If the heating element is causing the fuse to blow or is tripping the electrics that is usually caused by an insulation fault. That is, continuity between one or both of the connections and the heating element and the metal on the element itself.

If you are very lucky you might be to detect this. There should be no continuity whatsoever between either of the connections and the metal of the element. However, unfortunately you often need a specialist insulation test meter to be able to detect low insulation.

It's possible that there is a fault on the insulation but it is not detectable by a normal continuity tester. So your only option is to gamble and replace the element or get in an engineer (unless you know someone with a mega or insulation test meter).

washing machine fusing electrics

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[davehere]

Thanks for your help Andy,

My multimeter does not detect a short between the connections and the metal of the element.

It does detect continuity between the element metal and the earth connection, which looks like that is normal?

The element is not going to come out easily as I have tried already and the rubber bit doesn't want to come out. Any good tips on how to proceed here?

Thanks,

Dave 

 

[Whitegoodshelp (Andy)]

Hello Dave. Yes that's normal the earth connection should have continuity with everything metal. If there was a dead short to earth in the element (imagine the element inside breaking up and part of it touching the outer element casing) then you would be to pick it up on your multimeter.

However, commonly what can happen is that there may be just a little crack in the insulation surrounding the current carrying part of the element. This means that there is no direct contact between the live part of the element and the casing.  But as soon as mains electricity runs through it, because it is powerful enough, it can jump the gap and short out.

This is why you need a specialist insulation test meter. Such a test meter runs 500 V DC through a part and can do the same as the mains electricity in jumping the gap and finding a weak point.

Regarding tips of getting the heating element out, that's why I posted the link in my last reply, which does just that 🙂

[davehere]

Thanks Andy, That all makes sense.

I managed to get it out without breaking anything. Its looking a bit rough.

 

I guess its time for a replacement.

Dave

 

[Whitegoodshelp (Andy)]

Nice one. Looks like that's the culprit. Make sure you carefully read my article for advice on refitting. You can under or overtighten easily. And make sure you properly test for leaks before pushing it back. 

[davehere]

Part installed. No leaks and no deaths and no more tripping. So that's a success.

Thanks for your help

Dave

[Whitegoodshelp (Andy)]

Excellent. Nice one cheers.