Electric/Gas query

When a youngster visiting Grandad the light bulb in the room exploded and set fire to the cord from the ceiling. Dashed to the sink - got a glass of water and threw it at the burning cord - it did the job but was told later that had the water made an arc to the electric current there may have been a bit of a problem.......

 

With respect mate. What actually causes the spark.
There are several ways.
1 button for all rings.
Depress Dial for ring till spark ignites.
Electric operated (appears not that one if no cable/plug)
Battery operated
Mechanically operated
Plus the fact that the igniter could be clogged/water If it's just individual and not all rings.
Else buy one of those trigger ones lol.

 

each ring has a button - turn button on and gas flows - then manually press button to ignite but nothing happens (same for all four rings) - can't see any battery.

 

Not exactly sure where it would be located but I looked up Bosch Hobs and batteries are a common feature. it's in the trouble shooting and specs. In their models. If you kept the manual. (Or look online) it might show where its located. But I couldn't find it.
1.5 vdc battery. Customer services might point out where it is. Or even a gas fitter if you know one. The manual online doesn't.