Tee,
The Guest chargers are manufactured using non-flammable materials. As a result, they will not support combustion.
I have a 2613 in my boat that is plugged in more than unplugged as I do not get to fish as often as I would like. The boat has been housed in my garage for the last 3 years, which is under the house. Am I concerned with a potential for a fire? Not at all.
Have a great day!
Sue D.