Gonna take a wild stab in the dark here. We have an RCCB feeding an RCBO. The RCCB as a device has no connection to earth, where as an RCBO does through that little white wire.(am I getting warmer?) I actually dont know why this is, I always thought that an RCBO was an MCB and RCD all in one. Neither an RCD or MCB has an earth wire, so why does an RCBO ? There must be a reason. Whetever that reason, this is what the problem is. If I am wrong, I am open to being shot down in flames, but its all I can think of at the moment !
Just had another thought.........................................................................Er, no thats not it either !
It may have only taken two minutes to fix, but how long did it take you to suss out Shake ?
Hi Spud
how long to suss out, well about 4 or 5 seconds to be honest.
CU was in garage, opened the garage door, looked up at the CU, saw RCBO sitting next to the RCCB which was on the left of the CU with main isol on the right.
New INSTANTLY that the RCBO had to be coming off the RCCB, and thought very quickly, "well i bet that aint helping......."
Oh and your theory, Spud
*dut dut dut dah dah* (that was a fanfare of trumpets)
*fireworks go off*
*everybody hugs*
you got it matey!
the little flylead on the RCBO is a functional earth, and the RCBO NEEDS it to be there to function/operate.
Therefore, some of the line current coming through the RCCB must be going through the line input of the RCBO and then being directed to earth through the flylead.
So the RCCB sees an imbalance. Why doesnt the RCBO trip?, well because the 'leakage' is from the RCBO input to earth, the RCBO has the same current flowing through the output as it has flowing back through the neutral, so it is happy
Well done matey, its certainly one to watch out for aint it?
ok mine was obvious, but with the 17th, you could well be getting RCBO's in sub-CU's coming off RCCB protected circuits
*Shakey claps the Spudmaster* (deliberate spelling mistake)