Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Selector switch in summer position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Does the yellow LED light on front panel,
and can sparking be heard or seen?
Note:
If lockout occurs (red LED ON), reset by pressing
the red lockout reset button.