CU replacement

Legal minimum, on completion, before energisation, it should be checked to be safe .


To BS7671, expect a set of tests results for each circuit for IR and either R1+R2 dead test, or maybe the Zs before it was turned off, and some notes about wire sizes suitable for the breaker that protects them.


It is not a regs requirement, but in reality to do some sort of check before removing the old one is a very good idea, as it saves time afterwards trying to fault find with the power off. Especially true if RCD protection is being extended to circuits that did not have it before, as there is a tendency for this to reveal hitherto unknown issues that mean with the new board you cannot get the RCD to stay on. Typically it all works just fine until it fires off at 5 o'clock on a Friday, or after lunch on Saturdays, just after you have put all the tools back downstairs in the truck.

Legal minimum, on completion, before energisation, it should be checked to be safe .


To BS7671, expect a set of tests results for each circuit for IR and either R1+R2 dead test, or maybe the Zs before it was turned off, and some notes about wire sizes suitable for the breaker that protects them.


It is not a regs requirement, but in reality to do some sort of check before removing the old one is a very good idea, as it saves time afterwards trying to fault find with the power off. Especially true if RCD protection is being extended to circuits that did not have it before, as there is a tendency for this to reveal hitherto unknown issues that mean with the new board you cannot get the RCD to stay on. Typically it all works just fine until it fires off at 5 o'clock on a Friday, or after lunch on Saturdays, just after you have put all the tools back downstairs in the truck.