I was doing some household cleanup in the storage room where my heat tank is located when I noticed a burn mark on the wall frame near the pipe that goes from the heat tank to the shower next room.
I'm of course not thinking that this is due to the hot water itself, so I can only believe that this happened during an electric short to the ground.
I have some questions about this:
How can I know if this is a recent burn mark or not?
Is this a sign that something is not grounded properly somewhere and that during a thunderstorm, similar burn mark may appear again?
How can I prevent that from happening again?
Should I call a plumber or an electrician?