You should have 12V being supplied to your trailer, Not 24 or 48. It won't start a fire but it may blow the 195 bulb in the marker lights.
I'm guessing You Have A Steel 2X3 Framed Trailer ? And not an aluminum I-Beam trailer or a small canoe trailer/water craft trailer with an open rail to test for current with an amp clamp
It's hard to say how test your trailer because there's so many different types of trailers ( sjv, sj, bj, ltv, lpb, pb, apb, sv, canoe, flat-bed, horse-trailer, etc ) the list goes on
But generally you have 4 amber lights on the front of the trailer, 2 tail lights and either a bar light of 3 separate red lights on the back. So another question I'm left asking is: are any of the lights dim, flickering, or are they just all off.
If it's all the lights that are off, Then It's your car, or the trailers main ground which should be on the bottom of the trailer near the tongue.
If it's just one side of your trailer then it's most likely your fender light which should have a quick connect, it may have fell out and bounces to the frame, each amber light has a separate ground aside from the main ground, That helps to determine the short in the trailer so all the lights don't go out at once while driving down the road
If you have a multimeter you can test from your ground to power where it connects to your vehicle, Then from ground to each signal wire for voltage (left blinker- yellow, right blinker- green, lights on black, Ground white, Brown is the railings ground) to make sure you aren't getting a short from the white ground wire or another one, You can even test one side on the trailer, For example: Left side, Yellow - Brown wires = Ohms of resistance and continuity and Right side: Green and Brown = The same ohms of resistance value and continuity,
If you set your multimeter on continuity you can put your red lead on the trailer and your black on the white wire on your trailer plug, if you get continuity your good
But it's always likely that you could have a pinched wire behind one of your amber lights
Then again, do you have electric brakes on your trailer or does it use fluid ;) you'll know because their will be an extra blue wire ( 5 prong )