Help!!!!!!!! Crabtree star breaker rccb

[Scornio]

Hi guys,

Bit stumped here.

Have an rccb split load Crabtree star breaker... Which is tripping with any load put on it. The only circuit which is on this rccb is my new 20a radial for sockets. I've done my cont at .46 my insulation passes at greater than 299. Did an Rcd test which passes .. Did a ramp test also and trips at 27mA
Checked the nuetral tails into the rccb they are ok... Am I missing somthing obvious?? Another thing tried doing a zs on no trip but it does trip. Tried swapping the rccb but same issue.
Thank you for help in advance

 

[Richard Burns]

Very likely that you have put the neutral of the circuit into the same bar as the neutral for the RCD (or that the bars are linked), this would cause the fault you describe.
It is also possible that on assembling the circuit accessories that a cable has been caught and would now give you low insulation resistance test results, but it would have to be a very specific fault to do this in the manner you describe.

 

[Scornio]

All insulation res tests passed on that circuit so no caught wires... And there are only the nuetral tails going into the rccb which cant go wrong or I've checked a few times already.

 

[telectrix]

post a photo of the CU with cover off.

 

[MDJ]

neutral to earth fault on a circuit which is not energised in the same board as the rccb, and I suspect it is somehow jumping through the rccb, if you have confirmed the rccb is fine and all tests on the circuit connected to it is fine then another circuit must be interfering somehow.

 

[Flanders]

Another neutral within the installation could be connecting to the circuit by two cables rubbing together were they go through a tight hole. I have had this when to many cables have been pulled through 1 conduit coursing a short between 2 different circuits