Neutral - Earth Faults

[Silly Sausage]

This may be of interest...

?Neutral to Earth? faults | Professional Electrician & Installer

and something else to think about...
You've got a circuit additionally protected by an RCD, MCB off, why does chopping the cable with your conducting cutters trip the RCD?

 

[Simonslimline]

Single pole MCB so Line conductor is isolated, Neutrals are terminated in a common neutral bar as are the CPC,S , my guess is that when you cut the cable some of the neutral return travels through the sidecutters and down the CPC to earth causing an imbalance and making the RCD operate.

Please explain if im totally off the mark here.

cheers.

 

[Silly Sausage]

Looks good to me Simon!
Caught me out a few times, thinking wtf!
Disconnecting the N is a good ploy when working on a live install.

 

[Simonslimline]

Done this a few times since i started training, makes you think before just cutting cables, on the other hand it shows the RCD is functional

 

[SirKit Breaker]

Done this a few times since i started training, makes you think before just cutting cables, on the other hand it shows the RCD is functional

I've done this on more than one occasion, and fairly recently, it does prove the functionality of the RCD, and it also shows how short the fuse is of the IT guru, who's server i had just shutdown!

Cheers………….Howard

 

[Paul.M]

Lol, I shut down a small call center (about 30 desks) cutting through a dead lighting circuit.

My defense talking to the manager was "Well, when you make a mistake you've got automatic spell check. We have fuses and RCD's. If they dont work, we are dead. I've just proved that your RCD works fine!"

Everyone went for an extra coffee break whilst the IT man worked his nuts off for 10 mins getting everything back up and running. In the mean time I disconnected the Neutral and went for a cig. (got away with it, just.)