Hob/earth fault??

[moosehead]

Problem in kitchen which I hope is not a propblem. Wonder if you can help.
Had to disconnect our hob for one day. decorating.

Did nothing to the wiring at all.

Re-connected last night and the system tripped.

Diconnected once again, checked for break in cable - couldn't see any.

Reconnected, turned back on - no problem. System didn't trip and hob works.

As a double check multi-tested the neutral and earth and found some resistance. Is this normal - should the system have tripped again?

Tks
Moosehead

 

[BJS_Spark]

It is normal to see some low resistance between neutral and earth because they are connected together at the origin of your supply. Depending on your supply type and earthing arrangement this can vary but is nothing to worry about. As for why it tripped in the first place may need further investigation.
What tripped? a MCB or RCD??

 

[moosehead]

It was the RCD - maybe it was just a surge after firing it up, but it is working okay now. I was more conerned with the resistance, I thought that all circuits should be 'clean'.

Tks

 

[Adam_151]

Turn the main switch off and measure the resistance between neutral and earth again, you'll most likely (or should do) find you get nothing.

 

[moosehead]

Thanks - I'll try that.

 

[Qedelec]

Moose, the most likely cause is the heating elements of the cooker absorbing some moisture whilst it was disconnected and causing a lower resistance between Neutral and Earth. This moisture will have burn off very quickly after first switch-on. Cookers are prone to this and is the reason most are connected to the non-rcd side of the board.
The elements are constructed by drawing the outer casing and inner conductor, with insulating mineral between. This means that the central conductor varies in distance from the outer and can break down on occasions.
Hope this helps.
And a merry Christmas to all our friends out there!!!

 

[moosehead]

Thanks Qedelec.

I'll also do the mains switch off test for comfort.

Thanks to everyone for their advice throughout the year & Merry Christmas to all.

Look forward to Part Q in 2008.

Cheers.