Cooker cable tripping main fuse

[leeroypenmut]

I have a problem with my cooker cable/circuit breaker when I went to replace the cooker switch.

I turned off the cooker circuit breaker and checked that the power was off - I removed the switch but the main breaker tripped.

There is no power on the cooker circuit but it sometimes trips the main breaker.

 

[morqthana]

I have a problem with my cooker cable/circuit breaker when I went to replace the cooker switch.

Why were you replacing it? Aesthetics, or was there something wrong?

I turned off the cooker circuit breaker and checked that the power was off - I removed the switch but the main breaker tripped.

When doing that, might you have touched N and E together?

There is no power on the cooker circuit but it sometimes trips the main breaker.

Still?

How "sometimes" is "sometimes"? Does anything trigger it?

 

[pete01]

Was it the rcd that tripped? That can still trip with the power off if you touch neutral and earth by mistake.

 

[ericmark]

Need to work out what tripped, seems likely a RCD, to work on any circuit we should isolate it, we often don't, but that does not make it correct, the Isolator as the name suggests, does isolate and so will the RCD shown, but the MCB only turns off the line, the other live called a neutral is left connected, so an earth to neutral fault can trip the RCD, the RCBO can be either single pole or double pole switching, so some do isolate and some don't.

The locking device will fit a MCB, which does point to it isolating, and with a TN supply we often only switch off the line, but that's not an isolation.