Cooker testing - help needed

[raustin]

Hi there - just been out to install a cooker. After confiming that the circuit is OK next was testing the cooker.

It is a 2nd hand cooker that the owner bought for £50. Checked earth continuity and that was fine. Moved onto the IR tests. Oven was OK with 33.8M ohms. Then the rings. This is were I need a bit of guidance.

1 ring gave me a reading of around 4M ohms, so that is fine. The other 3 gave next to no resistance at all, around 0.1M and less.

So not too sure if the rings are OK as I know you can get very low readings. Just strange that one is OK.

So I have done a functional test. Oven OK and 3 of the rings work but 1 trips the RCD, so suspecting that the element has failed.

But still concerned that 3 of the rings failed the IR test.

Have told the user that I'm not connecting the cooker.

Any advice please guys.

Cheers Rich

 

[telectrix]

possibly 1 ring faulty and the netrals are common so you get a fault on the otheres as well.

 

[raustin]

possibly 1 ring faulty and the netrals are common so you get a fault on the otheres as well.

OK thanks so the fact that 1 ring is faulty will make the other rings IR low (i get that as neutrals are common). What about the one ring that measured around 4M ohms. Any reason why that reading was higher?

Would you have done the same by not connecting the cooker up?

As its a 2nd hand cooker, is it worth trying to repair. I would have thought would be best to buy a new oven.

 

[telectrix]

that is the best solution -- a new cooker. i would have left it unconnected as if there were to be a disaster, it would be me in court. i also get the customer to sign that i have not connected it. it's not unknown for the numpties to conect something up, then blame the sparks when the house burns down. ( or is it burns up )

 

[RogertheBodger]

Hi Raustin.
Not sure you have tested the cooker correctly, to test a (disconnected) element you should continuity test it and expect a reading of 70 - 80 ohms depending on the size of the element.
If you are IR testing it ( between the element and earth you should expect a reading of >200M ohms. Sounds like the element with a reading of 4m is the faulty one to me.

But as Tel says - is it worth it?

 

[raustin]

Thanks guys for the advice and observations. Thats put my mind at ease that I have advised them right. Great help as always. Have good weekend.
Cheers
Rich

 

[Knobhead]

Bet you’re the flavour of the month with a couple of newly weds that have spent what they could afford.

Personally I would have split each element and tested individually. Leave the one that’s tripping the RCD disconnected. On reconnecting allow all the elements to heat up for ½ Hr then retest. Radiant elements use aluminium oxide as the insulation, like pyro it absorbs moisture. Heat will dry it out.

OK I’m retired and have time to spare. Someone buying a 2nd hand cooker usually does so out of necessity.

 

[telectrix]

good comment, tony, but he could spend 3 hours just getting it to partially work. the labour cost might be better spent towards a new or good second hand ( seen working before buying ) cooker.

 

[pushrod]

0.1MΩ is a 100,000 ohms. I would have thought the more relevant tests were continuity, unless you have manufacturers specs. Something like 53Ω for a 1000W element and any continuity between L/N and earth and it is obviously deceased.

 

[telectrix]

like a norwegian blue parrot. it is deceased, it has ceased to exist, it's dead.

 

[pushrod]

like a norwegian blue parrot. it is deceased, it has ceased to exist, it's dead.

that... or it is just resting