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R

ritchiehulse

Been testing today on a new installation, it was a lighting circuit all lighting weird via click roses. Came to the rcbo test, trips on 5x at 100ms then says plus 40 on 5x. Quickly swapped out rcbo thinking it was just faulty and does same again with the new one. Some rooting around in loft i notice the air con lads have connected a air handling unit to the circuit, not a prob as they dont take many amps, disconnect it and retest, 28ms on 5x, anyone else had this happen before? something to do with the motor perhaps? ask the aircon lads and they say never had it before, they checked the unit and all was working fine with the unit, just baffled me abit thats all.
 
If there is a capacitance effect on the circuit, as can come from connected equipment, particularly electronics, then this can prevent the current being introduced on to the circuit by the tester from being registered as it is being briefly stored.
It is generally best to test an RCD with no connected load on the circuit.
 
You would notice very similar results when RCD testing and a fridge still plugged in as well , as said always best with all loads disconnected ....
 

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