RCBO will not turn on

[rustynails]

Hi all,


I'm having a problem with a newly installed RCBO. Having made alterations to a lighting circuit in a bathroom I recommended to the builder that the MCB on a 16th edition consumer unit on the non-rcd side be replaced with an RCBO as per 17th edition. I completed continuity ok, insulation resistance 0.54, not great! Attempted to turn on RCBO and it won’t turn on. Fault on the wiring. I hate fault finding. Why won't it just work. I put the MCB back no problems. Tomorrow I have to do the usual thing and explain to the customer why I emptied there linen cupboard to install an RCBO which they haven’t asked for and that I have no idea how long it will take to resolve the issue. What concerns me is that if It were a borrowed neutral this would allow the rcbo to be turned on but trip when under load? The rcbo not turning on is disconcerning.

 

[buzzlightyear]

why why Delilah, would it be best to ring your local sparky.

 

[littlespark]

Faulty RCBO? can happen.

If everything is checking out with tests, then its a possibility.
What was the alteration? can you isolate parts of the circuit to pinpoint what might be the cause?

I had a problem last week where a new kitchen under cabinet LED would trip the main RCD every 3rd or 4th switch operation. Replaced the driver and all is well.

 

[Dillb]

You have carried out a install in a circuit with a lor IR, why did you not carry out any testing before starting the job?

 

[westward10]

I don't suppose you tested the circuit prior to the alterations.

 

[Dave OCD]

To be honest you can't just ignore that insulation resistance either.

 

[buzzlightyear]

the op could have put in a rcd spur near the bathroom if possible
then putting a rcbo on the main circuit. to the bathroom .
because the fault could be any where .

 

[Pete999]

Hi all,


I'm having a problem with a newly installed RCBO. Having made alterations to a lighting circuit in a bathroom I recommended to the builder that the MCB on a 16th edition consumer unit on the non-rcd side be replaced with an RCBO as per 17th edition. I completed continuity ok, insulation resistance 0.54, not great! Attempted to turn on RCBO and it won’t turn on. Fault on the wiring. I hate fault finding. Why won't it just work. I put the MCB back no problems. Tomorrow I have to do the usual thing and explain to the customer why I emptied there linen cupboard to install an RCBO which they haven’t asked for and that I have no idea how long it will take to resolve the issue. What concerns me is that if It were a borrowed neutral this would allow the rcbo to be turned on but trip when under load? The rcbo not turning on is disconcerning.

0.54 what and between what?

 

[rustynails]

because the fault could be any where .

best line so far...

0.54 what and between what?

0.54M ohm between live conductors and earth.

 

[LankyWill]

No point whingeing about why don’t you grab your test kit and start fault finding. If you designed the install you need to live with your decision and fix the problem.

 

[Pete999]

0.54 M ohm not good doesn't fill me with confidence either.

 

[Octopus]

0.54 M ohm not good doesn't fill me with confidence either.

Not really low enough to trip a rcbo.........

If you don't like fault finding, maybe you consider an alternative career?

 

[rustynails]

No point whingeing about why don’t you grab your test kit and start fault finding. If you designed the install you need to live with your decision and fix the problem.

I designed the small alteration ie: made a pull cord into a light switch. Then went to the board only to find no rcd protection for a low voltage circuit in a location with a bath/shower.

 

[Pete999]

Not really low enough to trip a rcbo.........

If you don't like fault finding, maybe you consider an alternative career?

Well below the recommended min though isn't it?

 

[rustynails]

If you don't like fault finding, maybe you consider an alternative career?

That's true. Just not overly experienced in fault finding.

 

[telectrix]

bet i could turn it on:

 

[telectrix]

bet i could turn it on:

 

[westward10]

Well below the recommended min though isn't it?

It is but I agree with Doc it shouldn't be enough to trip the rcbo.

 

[buzzlightyear]

their only one way of knocking a nail in ,rusty nail.

 

[elsparko]

Hi all,


I'm having a problem with a newly installed RCBO. Having made alterations to a lighting circuit in a bathroom I recommended to the builder that the MCB on a 16th edition consumer unit on the non-rcd side be replaced with an RCBO as per 17th edition. I completed continuity ok, insulation resistance 0.54, not great! Attempted to turn on RCBO and it won’t turn on. Fault on the wiring. I hate fault finding. Why won't it just work. I put the MCB back no problems. Tomorrow I have to do the usual thing and explain to the customer why I emptied there linen cupboard to install an RCBO which they haven’t asked for and that I have no idea how long it will take to resolve the issue. What concerns me is that if It were a borrowed neutral this would allow the rcbo to be turned on but trip when under load? The rcbo not turning on is disconcerning.

why wont it just work? because someone has wired it up incorrectly

the whole point of testing is to find out faults BEFORE turning the magic back on

id rather fault find than carry hundreds of storage heater bricks to the top floor of a 5 floor building