rcbo tripping

stevethespark86 · May 11, 2012

im in new zealand now by they way although i was trained to city and guilds. we dont do testing over here, its retarded i dont even have any test gear apart from bog standard multi meter. i recently did a domestic install where i had to install a new sub board downstairs. i did the pre wire but the numpty that owned the house moved a lot of my cables and just gibbed over a light switch because he didnt want it there any more. which is bad in nz as they go to the switch first then to the lights (neutrals and all at switch) anyway i fitted it all off and installed an 40amp rcbo cpvering the 4 mcbs (2 socket circuits and 1 light and 1 alarm) as this is what my boss wanted. but the rcbo trips the minute any of the lights are turned on or anything is plugged into the sockets. if nothing is swicted on its fine. i took out the rcbo and just used the mcbs and main switch and everything was fine. any idea why this is? I have said before i dont have a tester as they are not really needed here. (talk about being rough here its a joke) i dont have any experience in domestic as for the last few years ive worked industrial with a bit of commercial (mainly power stations and mines etc) so i need a bit of help thanks.

truckster · May 11, 2012

stevethespark86 said:
we dont do testing over here, its retarded i dont even have any test gear apart from bog standard multi meter.

WTF?

I would think your neutrals are not all going through the RCBO(RCD?)

stevethespark86 · May 11, 2012

i know mate the word cowboy is not enough. seriously my company just did a medical center and all we tested was the mains. lol its shamefull cant wait to leave here. my neutrals are all going through i tried fitting the rcbo at the subboard and at the main board if you know what i mean, sorry im crap at describing stuff. i really have let my standards fall a lot over the year ive been in nz. i'm kinda embarrassed to call my self a sparkie at the minute

truckster · May 11, 2012

As you describe it without testing you are shooting in the dark. If the rcbo stays in with no load and the circuits work when no rcbo is fitted I am guessing at a neutral fault or two. Do any circuits work individually, ie the alarm?
If you only have the one rcbo shared neutrals shouldn't be a problem unless a stray one is connected from the other board.

stevethespark86 · May 11, 2012

no none of the circuits work individually. the minute anything is turned on on any of the circuits the rcbo trips. i guess without test gear im screwed then. thanks anyway. i thought it was a fault with the neatrals mabey at the main board ill check there again see if there is anything weird going on.

ackbarthestar · May 11, 2012

If all of the circuits are protected by a RCBO then:
1/ you have a mix up with the neutrals and cpcs at the board
2/ you haven't connected the outgoing neutral from the RCBOs correctly.
3/ Cross linked cpcs across the final circuits with a cpc neutral link at some point
4/ Knackered RCBO

To test the RCBO you will need a RCD tester

Des 56 · May 11, 2012

i guess without test gear im screwed then
It does help

You can obviously narrow the fault down using the rcd as the tester
No circuits connected,fit a temporary socket at the rcbo and check if the supply is ok
Then reconnect individual live +neutrals for each circuit

ebillthekid · May 11, 2012

stevethespark86 said:
im in new zealand now by they way although i was trained to city and guilds. we dont do testing over here, its retarded i dont even have any test gear apart from bog standard multi meter. i recently did a domestic install where i had to install a new sub board downstairs. i did the pre wire but the numpty that owned the house moved a lot of my cables and just gibbed over a light switch because he didnt want it there any more. which is bad in nz as they go to the switch first then to the lights (neutrals and all at switch) anyway i fitted it all off and installed an 40amp rcbo cpvering the 4 mcbs (2 socket circuits and 1 light and 1 alarm) as this is what my boss wanted. but the rcbo trips the minute any of the lights are turned on or anything is plugged into the sockets. if nothing is swicted on its fine. i took out the rcbo and just used the mcbs and main switch and everything was fine. any idea why this is? I have said before i dont have a tester as they are not really needed here. (talk about being rough here its a joke) i dont have any experience in domestic as for the last few years ive worked industrial with a bit of commercial (mainly power stations and mines etc) so i need a bit of help thanks.

Hi mate,
For starters you don't want the alarm thru the RCBO, as there's no point fitting an alarm if a slight fault on any circuit will disable it.
But if you don't have an RCD tester or especially IR tester, there's almost no point fitting one! How can you prove it compies with 200mS @ I-delta-n?
Allowing then for correct installation according to mfr instructions, making sure neutral goes to the correct neutral terminal bar if a split board, it could be that there is a slight earth leakage from a live conductor on one cct. This may not be enough to trip the RCBO off load, but the slightest load increases leakage current flow and trips it. You didn't say if it trips on one cct with ALL OTHER breakers off, this is crucial and will verify if one cct is faulty. Maybe they all are!
Look out for water ingress.
Otherwise, it may be a duff RCBO which is nuiscance tripping under any load.
What make is it? Beware of unknown brands from the orient.

Good luck, Will

stevethespark86 · May 11, 2012

cheers people i will go back monday and try some of these things. it is vynco, they are a good make over here apparently. i think that in new zealand it 'complies' with the rags as long as it dont catch fire before you leave

it does trip on 1 circuit with all other breakers off, only when i turn something on, on that circuit. so say if i have all them off bar the lights and i turn a light switch on it will trip. if i have all circuits off apart from the skts and i plug something in, it will trip and so on. i'm going to try and see if someone i know has an ir tester as well.