Set Appliance State:
Gas Off
Set Multimeter to AC Voltage 
CH Demand
Use Insulation Mat as required
Isolate Mains Power to appliance as per TOPs P4
Gain access to boiler terminal block
Gain access to boiler terminal block
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
With the Fan running measure Mains Voltage across the Brown wire connection marked L1 on the PCB connector and the Blue wire connection marked N (connection1) on the main connector block.
Isolate as per TOPs P4
and refit as necessary