Can anybody help please .I have installed a new lighting circuirt for the bathroom , comprising 2 28 watt lights and 1 selv fan . when the pull switch is turned of the rccbo trips , not all the time but every 5 to 6 times . i have meggered cables and they are all above 299meg ohms. I have swaped both lights and transformer and pull switch . i have ram tested the rccbo and that trips of at 21milli amps ..which crabtree say is fine...can anybody help i am totally lost many tanks
rccbo tripping
- Thread starter derbyphil
- Start date
Just to clarify, is it an RCBO or an RCCB (RCD) that you have installed? An RCBO will also trip in additional situations to an RCD as it provides overcurrent protection too.
Any chance of a shared neutral? I'm guessing not if it's all new cable installed. Any screws through the cables? Again probably not if its new!
Have you tried the energising the circuit with the SELV fan disconnected? Possibly some problem with the fan?
Any chance of a shared neutral? I'm guessing not if it's all new cable installed. Any screws through the cables? Again probably not if its new!
Have you tried the energising the circuit with the SELV fan disconnected? Possibly some problem with the fan?
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Sounds like a borrowed neutral problem!
Another thought - if you insulation resitance tested the fan at 500VDC you may have damaged it. Not sure how likely this is though. 
As I undertsand it, an SELV circuit should be tested at 250VDC. But I could be wrong.
As I undertsand it, an SELV circuit should be tested at 250VDC. But I could be wrong.
the selv circuirt and lights was disconnected when i tested it and the cable is under floor boards and in mini trunkingAnother thought - if you insulation resitance tested the fan at 500VDC you may have damaged it. Not sure how likely this is though.
As I undertsand it, an SELV circuit should be tested at 250VDC. But I could be wrong.
cant be a borrowed neutral as new circuirt is fed from a new 5 way board and only other circuirt on the board is the shower pump and that is on a seperate rccbo
is it consistently every 5 or 6 times, or when you happen to be standing in a particular spot and shift your weight from one foot to the other?
nail through a cable under the floor.
nail through a cable under the floor.
Have you tried another RCD/RCBO in its place?
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