Even with no mains power to the hob, you should still be able to use it. You just turn, press and light it with a match, then count to five before releasing. The mains power is just for the ignition system.
Idea is, that should the flame blow out, the thermocouple cools and releases the gas valve - fail safe.
Idea is, that should the flame blow out, the thermocouple cools and releases the gas valve - fail safe.