Microwave pat test fail

[Rossco107]

I have an expensive microwave / oven that has failed a pat test on low resistance - im not sure on which cables. I had a domestic repair company look at it and they can find no fault. It works perfectly. Is there a high probability that the mains cable has a kink and replacing it would be the fix? I really dont want to scrap it.

 

[jj4091]

The domestic repair compant should have PAT tested during examination so I can't see why someone else should fail it or what he/she means by low resistance.If they say it's not faulty then ask whoever failed it why. If the socket you have it plugged into is suitably protected and it's working ok I can't really see why it should have failed. Unless he was being particularly finnicky and it was a crack in the outer sheath of the cable or something similar.
Are you saying the cable has kink in it and suspect that's why it failed, then examine it closely for any breaks in the sheath. If it has then it only needs mechanical protection ie wrap some tape around it.

 

[jj4091]

Just seen your repeat post in the electrical section which I think that the answers agree with mine.

 

[Rossco107]

Thank you for your replies

 

[ericmark]

I have an expensive microwave / oven that has failed a pat test on low resistance

I do wonder if that means the continuity test shows resistance not low enough, or if the insulation resistance test shows the resistance to be too low?

I would be wary of testing insulation resistance at 500 volts, it could cause damage, and it could also give a false reading if there is any surge protection device fitted, so would test at 250 volts. What would be better is to measure leakage current (assuming the RCD does not trip) which should be 3.5 mA or less, as above that special wiring to sockets is required, but I would have said earth leakage too high, not low resistance.

The resistance not being low enough, would mean should a fault happen, the fuse/MCB/RCBO/RCD would not disconnect within the required time, I have seen this with very long extension leads, and the cure if used where a RCD does not already exist was to fit a RCD plug on the extension lead.

But with a microwave, one would assume a bad connection inside the unit.

I hated PAT testing microwaves, as I was not testing for microwave leakage, and to put a sticker on the unit to say OK to use without testing for leakage seemed wrong, even when it was not technically required. Felt the same with grinders with missing guards, or on/off buttons which could be latched on, I did not want to say electrical OK, as the green label makes people think they are safe.