New Consumer Unit Issues

[lemonslap]

Hi All, I have just upgraded my main consumer unit in my house but have found an issue when I atempted to upgrade the garage one. The garage is fed with a SWA cable from a 40amp MCB protected by a 80amp RCCB to a 63amp RCCB located within the garage, then this feeds one 6amp MCB and one 32amp MCB. The issue is if any load is applied to the garage RCCB it trips out, I have tried isolating circuits and checked all the wiring with no luck.. If I replace the RCCB for a main switch all works fine, help please!

[Gaz413823]

Hi , I'm not a hundred per cent clear how you've got this wired but it sounds like you've got a neutral fault , possibly a neutral connected directly into the neutral busbar when it needs to go into the rccb

[lemonslap]

Gaz413823 said:

Hi , I'm not a hundred per cent clear how you've got this wired but it sounds like you've got a neutral fault , possibly a neutral connected directly into the neutral busbar when it needs to go into the rccb

Thanks Gaz, All wired correctly. Its a schneider easy9 consumer unit if that helps, netrual is prewired from the RCCB to the busbar. I have tried disconnecting circuits fully leaving only one in place at a time with no luck.

[Gaz413823]

Ok , with the garage breakers turned on but with no load , do they hold in or do they trip straight away. What sort of cu is the one in the house that you have upgraded ? Is it a split load board with some circuits on one rcd main isolator and the rest on a main switch ?

[v12bitch]

not sure if a circuit likes two rcd protecting one circuit if ive read you right ?

[lemonslap]

Gaz413823 said:

Ok , with the garage breakers turned on but with no load , do they hold in or do they trip straight away. What sort of cu is the one in the house that you have upgraded ? Is it a split load board with some circuits on one rcd main isolator and the rest on a main switch ?

No load nothing trips on the garage, only on load does the RCCB trip but not the MCB. The main board in the house is spilt loaded however both sides are protected by a 80amp RCCB each.

[lemonslap]

v12bh said:

not sure if a circuit likes two rcd protecting one circuit if ive read you right ?

This is my thinking, however from reading up it's supposed to work?

[Gaz413823]

Ok , in the split load board in the house how many neutral bus bars is there? I'm expecting two . Is it possible the garage circuit neutral conductor is connected into the wrong bus bar? I know you said the wiring is correct and apologies if it is but this might explain your problem. A circuit protected by two rcds is fine , if the wiring is definitely correct then the only answer is a faulty rcd. Have you done any testing on the installation? R1+ r2 , ir etc

[lemonslap]

Gaz413823 said:

Ok , in the split load board in the house how many neutral bus bars is there? I'm expecting two . Is it possible the garage circuit neutral conductor is connected into the wrong bus bar? I know you said the wiring is correct and apologies if it is but this might explain your problem. A circuit protected by two rcds is fine , if the wiring is definitely correct then the only answer is a faulty rcd. Have you done any testing on the installation? R1+ r2 , ir etc

Yes correct on the main CU, however the neutral is on the correct Bus-Bar, I also swapped out the RCCB for a new one but the results were the same. I also removed the feeds and connected up a extension lead, this gave the same results. I can't perform any of the installation tests as I don't have the kit, however I will ask one of my trade contacts to do me a favour on this I think..

[ch427]

id say you have a neutral/earth fault in the garage somewhere that only shows under load. May be as simple as a trapped neutral in one of the socket backboxes etc.

[v12bitch]

thinking now live and nuetral reversed in one of the socket connections?? easily done if used to wiring a certain make as some are laid out diff, just another thought

[lemonslap]

Thanks all, however I have disconnected all the circuits (lives, neutrals & earths) and tried them one by one with the same effect. I know the internal lighting circuit is 100% at least as I rewired it earlier in the year.

[Raverbaby]

Any pics of the 2 consumer units with the cover off?

[lemonslap]

Raverbaby said:

Any pics of the 2 consumer units with the cover off?

Will post up tomorrow.

[GnuBee]

You probably have but just in case; have you tested the test load e.g. it's not your test load that's actually the source of the fault...