Discuss RCBO tripping next door RCBO in the Electrical Forum area at ElectriciansForums.net

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Testing an RCD on one rfc upstairs tripped the upstairs and downstairs circuis, which was the RCBO next door to it. Turned off the power to all circuits tested downstairs RCBO on its own RCD failed 1x and 5x tests. Disconnected conductors from this RCBO tested RCD at the board worked ok. Put cables back in failed RCD tests. Removed every fuse from every fuse spur and disconnected all plugs etc. Tested ok. Put all the fuses back and all plugs switched on tested again all ok. went upstairs tested rcbo tripped individually. madness ?
 
I’m still confused lol once I’d disconnected everything on the circuit the RCBO passed the RCD tests.

Before that it was only passing if I disconnected the conductors from the RCBO.
Before that it was only passing
was it passing when you tested it with out the circuits being on or off .;)
 
topic title somewhat misleading in this context, i.e. "next door"

When I say next door I mean in the box.

was it passing when you tested it with out the circuits being on or off .;)

This occurred when I auto rcd tested upstairs RCBO sockets ‭which was tripping both upstairs and downstairs. The first time I got the Rcbo to pass was when I disconnected all other circuits and disconnected the conductors from the rcbo and rcd tested at the origin.
 
Polarity in accessories, did you do an R1R2 and test every point? Not sure if that would cause your issues!
 
Seen some people on here talk about N-E faults causing a RCD to stop operating, never seen it myself but I sure someone else will be able to explain.

Have you tried an insulation resistance test between the two circuits with them disconnected from DB? Perhaps you have a bit of a short between the 2 circuits if they are causing each others RCBO's to operate. Cable burns from installation maybe.
 
"Removed every fuse from every fuse spur and disconnected all plugs etc. Tested ok"
So with all loads removed the circuit tested ok?
Could one of the appliances be leaking DC or not compatible with an AC type RCBO (assuming it is an AC type RCBO)
 
This same thing happened to me a few weeks ago. It was very confusing. I went home, came back the next day refreshed and figured it out.

Have you done any IR tests? You need to see if one (or more) circuits have IR faults. My RCD would not trip when tested with the conductors all in place but when I disconnected them the RCD tripped as it should when tested, therefore you know there is no fault with the RCD. Two of the circuits tested as 0Mohms N-E. I found the fault(s) reconnected everything and the RCD passed the tests.

For some reason, on rare occasions, a N-E IR fault can actually stop the RCD from working. I don't know why.
 
If you have a neutral to earth fault of there is no guarantee this will cause an imbalance because the current may still predominantly pass back through the neutral as opposed to earth hence the rcd may not trip. TT systems are prone to this due to the higher impedance of the earth path so the neutral just chooses not to divert that way.
 
If you have a neutral to earth fault of there is no guarantee this will cause an imbalance because the current may still predominantly pass back through the neutral as opposed to earth hence the rcd may not trip. TT systems are prone to this due to the higher impedance of the earth path so the neutral just chooses not to divert that way.
But that would not explain why the RCD is not tripping when tested?
 
I believe a neutral to earth fault can desensitive the device by putting a load to the current transformer which effectively raises the trip sensitivity.
 

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