Blue? fuse tripped while working on circuit that was off...arching?

[Hobobanobo]

Went to change a socket.
Turned kitchen sockets off at mcb.
Tested and was no power to socket. Or kitchen.
Started to connect new socket.
Blue fuse tripped and took out power to other circuits... dont understand. Or know what that means?
All fine now but blue fuse has red marker.
What do I do with that red marker now?
Note: heater and oven off as needs wiring moving for wall replanted and socket move. which was next job. Dont feel safe doing it now.
Thanks.

 

[EFLImpudence]

It is not a fuse but a Residual Current Device which detects current leakage to earth.

You must have touched the neutral and earth together.

Perfectly normal and nothing to worry about. Just switch it back on.

 

[Murdochcat]

The "blue" fuse is the RCD. Replace socket, fix to wall , reset RCD and MCB

Should be live again

 

[Hobobanobo]

It is not a fuse but a Residual Current Device which detects current leakage to earth.

You must have touched the neutral and earth together.

Perfectly normal and nothing to worry about. Just switch it back on.

I was moving the wires about when it tripped even though socket wasn't live. Likely did touch. So makes sense

 

[Hobobanobo]

The "blue" fuse is the RCD. Replace socket, fix to wall , reset RCD and MCB

Should be live again

I did and it seems ok now bar the red mark under it.

 

[EFLImpudence]

Doesn't the red marker just mean it is switched on?

 

[Hobobanobo]

Doesn't the red marker just mean it is switched on?

Hopefully
I'm suprised it did that if the fuse was off while working on it. Does it still have current when off. I'm sure I'd have known about it being live when touching the wires to replace switch. Just confused me.

 

[EFLImpudence]

Hopefully
I'm suprised it did that if the fuse was off while working on it. Does it still have current when off.

Yes, the Neutral is not disconnected by the MCB and all the Neutrals on the RCD side are connected together which in turn are connected to earth at the source so current can flow when touching earth.

I'm sure I'd have known about it being live when touching the wires to replace switch. Just confused me.

You might be wise in future to switch off the Main Switch even though inconvenient.

 

[bernardgreen]

This explaind why an RCD will trip when the MCB for the circuit is switched OFF