Dodgy breaker or wiring

[fizzy]

Mates house.
RCD keeps tripping on the cooker circuit. Doesn't go straight away takes about 10 minutes.
Cooker circuit breaker itself doesn't trip.
There is a cooker mains switch with a socket attached. This is fine. Even when the cooker switch is OFF the RCD trips.
The cooker looks very rough. Could it be tripping the RCD even with the mains switch off? I wouldn't have thought so.
I once had something similar and it turned out it was the 32amp breaker itself causing the rcd to trip!
Any ideas?

 

[Misterg]

Could it be tripping the RCD even with the mains switch off?

If it's a single pole switch, yes.

 

[fizzy]

If it's a single pole switch, yes.

I thought that might be the case!
I will pull the wires out of it and check.
There is another mini junction box that connects the cooker lead. Place is very damp. The screws have lost their heads they are so rusty so will drill them out and replace the box.

 

[Misterg]

I thought that might be the case!

Yes, it could be a leak between neutral and earth (cpc ).

 

[colnerov]

Is the oven element on the way out, if it hasn't gone already?

 

[Blobber]

I thought all cooker switches were double pole, never seen one that isn't, if it's a combined switch with socket then the socket part could be the problem

 

[Mark 5]

If it's a single pole switch, yes.

What is a single pole Cooker switch?

 

[brightspark]

What is a single pole Cooker switch?

there isnt one there all double pole theres a double pole isolator switch or a cooker controll switch with socket check the switch to make sure its not knacked and letting power through

 

[Mark 5]

there isnt one there all double pole theres a double pole isolator switch or a cooker controll switch with socket check the switch to make sure its not knacked and letting power through

I didn't think there was.

 

[Nomad]

Dodgy MCB?

Relatives had a new shower fitted. For a few years they lived with it occasionally tripping the dedicated MCB (RCD?), I swapped out MCB/RCD when I was living there for a month and the new one never tripped. Verdict was the original fitted when the shower was first installed was a fraction too sensitive.

 

[Misterg]

What is a single pole Cooker switch?

I read it as 'the cooker being switched off' (i.e. isolator on, but all controls off), rather than the 'cooker switch' (= isolator) being off - sorry.

 

[brightspark]

its pointless doing wild guesses. just disconect the circuits unplug appliances and do an insulation test on them

 

[fizzy]

Dodgy MCB?

Relatives had a new shower fitted. For a few years they lived with it occasionally tripping the dedicated MCB (RCD?), I swapped out MCB/RCD when I was living there for a month and the new one never tripped. Verdict was the original fitted when the shower was first installed was a fraction too sensitive.

I had that but the mcb was also tripping. Drove me mad as it was intermittent. Turning off loads of appliances. Then I thought mice had chewed the wires. Swapped out the mcb all fine!

 

[Brad93]

Insulation resistance test required.

Probably the element going bad.

I've had elements on industrial dishwashers still heating but tripping occasionally.

 

[Onoff]

Cold elements often no issue. As it heats up things expand putting parts that shouldn't touch closer together.

Also check the security of all screw terminations on the cooker circuit.