Why does the fuse box get hot? | Mend Caravans No fuse box should get very hot. it is, the fuse has too low a rating and could blow at any time, or there is an electrical fault somewhere, maybe in the form of a loose connection which is inducing some resistance. A degree of warmth is acceptable however. John July 2009 Practical Caravan: fuse box getting hot (1/1) Hi we've just come back from the Alps and while we were there we noticed a faint smell of plastic meltinging into it we traced it to the fuse box which is under the front seating area were on hook up for almost 3 weeks using the electric heating most of the time idea's what could cause this?The van is a bailey auvergne 2005.