Set Appliance State:
Gas On; Pilot On
Set Multimeter to AC Voltage 
Isolate Mains Power to appliance as per TOPs P4
Rotary Switch in DHW position
Keep Boiler Case Switch depressed
Remove the 3 amp fuse, insert the positive probe into the fuse holder.
Rotary Switch in DHW position
Keep Boiler Case Switch depressed
Remove the 3 amp fuse, insert the positive probe into the fuse holder.
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure voltage across the fuse holder base and the Neutral (blue wire terminal marked N) on the main terminal block.
Note:
Ensure that probe has good contact with base of fuse holder.
Note:
Ensure that probe has good contact with base of fuse holder.
Isolate as per TOPs P4
and refit as necessary