Can't reset the RCD with any MCB's on - Faulty RCD?

[Geoff101]

So for those following this exciting thread who like a happy ending....(!)
Managed to get a local spark out this morning. Ran the circuit tests - all ok.
Swapped the rcd for a BG one which has the L N connections on the opposite sides.
Rcd reset first time with all MCBs on! Result!
I’ll look at the options for a new CU with a bit more space in the new year.
So I think Marconi wins the prize for spotting the wrong handed rcd. Cheers!
Thanks to everyone who contributed and helped move the thinking on. At least you got to find out the ending!

 

[DPG]

Great stuff. Thanks for letting us know.

 

[Bul]

Hi - I might be the only person that didn't quite understand the wrong handed rcd. Could anyone explain it again or do a line drawing. I might be slow but I'm honest and interested.

 

[Geoff101]

Hi - I might be the only person that didn't quite understand the wrong handed rcd. Could anyone explain it again or do a line drawing. I might be slow but I'm honest and interested.

If you look back at my pic of the CU you'll see the RCD is mounted on the right hand side of the CU. The live is therefore goes on the left of the RCD as this has to connect to the live bus and the neutral goes on the right. In my case the RCD had been replaced with a more recent model to that originally fitted. The newer CU's (which this was designed for mount the RCD at the left hand end). These therefore need need the RCD designed to have the live on the right hand side to connect to the live bus and the neutral on the left.
As my old style one had been replace with a new style one without the person realising the difference it meant that the RCD had it's live and neutrals reversed which was causing the tripping problem when trying to reset it. The house supply was not reversed - just the RCD. Hope this makes more sense. No problems since!

 

[Squid]

Haven't read the full thread but always reset the board with all breakers in the off position then turn them on one by one as certain circuits may have a high load connected to them,, think PC's firing up as on auto reboot etc etc.

 

[DPG]

Haven't read the full thread but always reset the board with all breakers in the off position then turn them on one by one as certain circuits may have a high load connected to them,, think PC's firing up as on auto reboot etc etc.

Good practice.

 

[Bul]

If you look back at my pic of the CU you'll see the RCD is mounted on the right hand side of the CU. The live is therefore goes on the left of the RCD as this has to connect to the live bus and the neutral goes on the right. In my case the RCD had been replaced with a more recent model to that originally fitted. The newer CU's (which this was designed for mount the RCD at the left hand end). These therefore need need the RCD designed to have the live on the right hand side to connect to the live bus and the neutral on the left.
As my old style one had been replace with a new style one without the person realising the difference it meant that the RCD had it's live and neutrals reversed which was causing the tripping problem when trying to reset it. The house supply was not reversed - just the RCD. Hope this makes more sense. No problems since!

Totally understand now - Thanks Geoff. This has been an extremely interesting thread and really shows the forum at it's best.