Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Remove the live, neutral and earth wires from the outgoing
side of the boiler terminal strip (to PCB) and make safe
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

With the wiring to the appliance isolated does
the fuse still blow / circuit breaker still trip?
Please choose one of the outcomes below:
FUSE NO LONGER BLOWS / CIRCUIT BREAKER NO LONGER TRIPS
FUSE STILL BLOWS / CIRCUIT BREAKER STILL TRIPS