RCBO question.

[tigerpaul]

Had a strange one the other day.

I was in a main switch room and had an RCBO connected into a DB, but switched off. From it was a radial in singles to a socket adjacent to the DB. The conductors were disconnected at the socket, if I touched the neutral down to earth, it sparked as though it was live, and the Main LV panel behind me started to hum.

Why was this happening?

 

[telectrix]

never mind why. what tune?

 

[Marvo]

A photo might help. If there was a flash between the neutral and earth then either the neutral is floating at a voltage wrt earth or the earth isn't actually at 0 volts. The RCBO doesn't appear to be providing isolation possibly either.

Sounds like it might be a good time to drag out the testers before it nails some other poor soul.

 

[tigerpaul]

Ok I forgot to mention, when I tested it I had 0v between L and E, but 2v between N and E.

The RCBO was in the off position when this was happening.

BTW, all live tests passed.

 

[trev]

Comment removed. I remembered I promised to be nice

 

[Marvo]

What earthing arrangement was it?

 

[tigerpaul]

TN-S

I'd have thought that with the RCBO switched off, there would not be any possibility of any potential difference between L N or E. Evidently not in this case.

 

[D80]

Was it a single pole RCBO?

 

[trev]

Comment removed-fight the urge trev, fight it

 

[tigerpaul]

I thought that all Rcbos were double pole... Duh! I guess I learnt something today then..

 

[Geordie Spark]

I thought that all Rcbos were double pole... Duh! I guess I learnt something today then..

:yes:

(The time to worry is when you stop learning !!)

 

[DurhamSparky]

only stop learning when your dead from not learning enough..!! and then that's a big lesson learnt for others...!!

 

[Geordie Spark]

only stop learning when your dead from not learning enough..!! and then that's a big lesson learnt for others...!!

Thank you.

That's exactly my point my Friend.

 

[jimmymac]

You know the old saying "everydays a school day" well it is for me because i forget everything