RCBO Tripping

[craig1]

Hello, Recently changed a 6A mcb to a RCBO on the upstairs lighting circuit. Having done this the upstairs landing light (two way) now trips the RCBO. I changed the mcb when creating an upstairs bathroom. As I used mostly plastic pipe for the plumbing I understand Bonding isn't required anyway? was thinking of getting the mcb refitted to solve the problem. I think the light is connected to the downstairs neutral which is causing the tripping. Any ideas?

 

[starspark]

Yes from what you have said it very much sounds like a borrowed neutral which has now only came to light when you changed to an RCBO.

 

[riveralt]

Get the electrician back who fitted it - sounds like it hasn't been tested properly.
It could be/but unlikely to be a faulty RCBO - check out the test results on the electrical installation certificates schedule of test results - they should highlight the trip times for the RCD side of the RCBO. They will also give you details of the R1+R2 results, Insulation resistance and other important tests. Pop the details on here.
It should also tell you which circuit the two way landing light is connected to.

 

[craig1]

Forgot to mention there are two smoke alarms also on the circuit. So changing back to the mcb would be ok considering the bonding?

 

[riveralt]

Forgot to mention there are two smoke alarms also on the circuit. So changing back to the mcb would be ok considering the bonding?

FFS

 

[RMS]

Agree with starspark.

Sounds like a borrowed neutral. Normally the landing light is the cause.

Why did the electrcian fit the RCBO. Has he worked on the circuit?


edited typo

 

[JohnD]

Hello, Recently changed a 6A mcb to a RCBO on the upstairs lighting circuit. Having done this the upstairs landing light (two way) now trips the RCBO. I changed the mcb

What electrician?

 

[riveralt]

Hello, Recently changed a 6A mcb to a RCBO on the upstairs lighting circuit. Having done this the upstairs landing light (two way) now trips the RCBO. I changed the mcb

What electrician?

John the question was raised more in hope than expectation.

 

[EFLImpudence]

Agree with starspak.

I agree with riveralt.

 

[craig1]

Thanks for the replies/advice. The bathroom installation has been inspected passed off and certified.

 

[Taylortwocities]

The bathroom installation has been inspected passed off and certified.

In that case, whoever completed amd signed the certificate (which includes confirmations of functional testing) has created a fraudulent document.
Get him/her/it to fix the problem.

 

[mikeyd]

I think the light is connected to the downstairs neutral which is causing the tripping. Any ideas?

Fix it. Borrowed neutrals are bad. Do not just put it back on an MCB.

It was a fairly common practice years ago to 'borrow' a neutral, but it was never a good idea.

 

[craig1]

Thanks for the info Starspark, I've now sorted the borrowed neutral problem. Tripping problem sorted. Yo!

 

[JohnD]

The bathroom installation has been inspected passed off and certified.

Thanks for the info Starspark, I've now sorted the borrowed neutral problem. !

Did we ever get to the bottom of this electrician who tested and certified it?

Is it the one who went off on a foreign holiday and can't be contacted? He often crops up on here, I can't understand how he makes a living.