I got a central water heater at home that runs on electricity
(not the gas type). The rocket switch for turning on/off the
heater (the one that comes default with my place)
burned out after +- 6 months of usage.
So the electrician came and replaced it with a normal switch.
But now after 3 months, sparks are flying out every now and then
whenever I switch off the heater. Is it the heater's problem? Or is
there another type of switch that anyone knows is more suitable for
water heaters?
You got a humidity problem.