No Side lights

hi all

now the other day i noticed that my drivers side rear side light was out, so i took the bulb out and noticed that is was a 24volt one and so was the other side . So yesterday i got some new bulbs (12v) and i still have no side lights on the drivers side at all as the fuse keeps on blowing even with a 30amp fuse in it still blows.Some times it will take out the side lights on the other side as well. So what do people think the problem could be?
many thanks
Kyle

I'd say you have a short to earth in the wiring for the side lights. Possibly a pinched or frayed wire touching the bodywork somewhere.