Why do the fuses trip when the power is off?

[dab160]

I have been putting some extra plug sockets in a bedroom upstairs, so switched off the upstairs ring main at the fuse on our split load fuse box. I checked that there was no power at the existing plug socket with my meter and removed the wires. However, when I touched the live and the nuetral wires together it tripped all the plug sockets in the house. These wires had no power going through them, I had touched them with my fingers, yet still they tripped the 13amp side of the fuse box. I had the same thing happen when I was installing extra sockets on the downstairs circuit. Can anyone explain to me why this would happen?

Thanks very much

 

[JohnD]

Perhaps you tripped the RCD.

What was the thing that tripped? What has it got written on it?

What was the thing you turned off? What has it got written on it?

Do you know what an MCB does, and what an RCD does?

 

[ban-all-sheds]

JohnD - you know full well the answers to those questions.....

 

[Steve]

aye cock, ya've tripped ya RCD!

"13A side of the fuse box"

The RCD looks for a difference between the neutral and live flowing through it. When you isolate one circuit on the RCD side, you are just isolating the live (you have single pole MCBs to isolate individual circuits). The neutral is still connected to the supply (though it is tied down to earth so you cant get a shock). Because the neutral at the socket is still connected to the other circuits in the house via the neutral bar in the CU, when you touch it to earth in the socket, current flows to earth instead of neutral (though both usually end up in the same place electrically, one goes through the RCD, the other doesn't). The RCD will pick up this as an earth fault and will trip. Nothing to worry about. The same usually happens on the non-RCD protected circuits too.

 

[dab160]

Thanks very much for the replies.

You are right, i dont know what an MCB or an RCD are, i shall go off and find out.

I'm not sure why i used the term '13amp side', I was trying to describe (badly) that my fuse box is split with the kitchen, upstairs, and downstairs ring mains on one side with a switch to turn them all off and the lighting circuits on the other with the switch to turn off all the fuses. It was the switch that turned all the plug sockets off that kept tripping.

Thanks again

 

[Adam_151]

I'm not sure why i used the term '13amp side', I was trying to describe (badly) that my fuse box is split with the kitchen, upstairs, and downstairs ring mains on one side with a switch to turn them all off

That would be the RCD, it should have a test button on it

and the lighting circuits on the other with the switch to turn off all the fuses.

The switch you speak of is known as the main switch/main isolator, CU incommer, etc. and the Fuses are speak of if they are like small switches are MCBs