Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Volts 
Gain access to PCB (use Insulation Mat as required)
Timer (if fitted) calling for heat
Timer (if fitted) calling for heat
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure voltage across terminal marked 3, white wire (this is the 7th terminal from the bottom of the main terminal block) and the neutral terminal, blue wire (2nd terminal from bottom of the main terminal block).
Isolate as per TOPs P4
and refit as necessary