Okay - Ill give you the long version ---
It sure sounds like your ground wire is hot, which suggests that it is making contact somewhere with a live wire. At the risk of stating the obvious - this is a potentially dangerous. situation. Unplug your trailer from its power source now, if you have not already done so.
I'm guessing you are at home with your 110v circuit plugged into a home outlet? The problem could be with the home circuit, the trailer wiring, or even any appliances with a grounded plug that you might have plugged into the trailer.
I would start by taking a careful look at that electrical
box - the one in the trailer. Has a screw or something else metallic fallen into it and created a bridge between the black 110v wire and the ground circuit?
I suggest you acquire a voltage tester. Plug one terminal into the live pole of the 110v outlet that the trailer power cord is plugged into (black wire/shorter slot for the plug in newer outlets) and the other into the ground hole and see what kind of resistance (ohms) reading you get. It should be infinitely high. If it is not - then the problem is the circuit coming from the house (if that is the case you might consider calling an electrician). DO THIS WITH THE POWER TO THE OUTLET OFF. Low resistance means that there is communication between the two circuits - a short.
If it is good, then move onto the trailer power cord. Those power cords take a lot of abuse. Unplug the cable on both ends and then test it by measuring the resistance between a live pole (black wire) and a ground pole (green wire), on either end of the cable - doesn't matter which end you pick. If the resistance is low the cord has a short in it - replace it.
If the power cord is good, then it check a trailer outlet just like you checked the outlet coming from your house. If you see low resistance between the live pole and the ground pole, start by unplugging all appliances - one at a time - and see if that makes a difference (fridge, A/C, 110v light
, etc). If it does - you have pin pointed your problem. The appliance or its cord is bad.
If you are still seeing a short at one of the outlets after all appliances are unplugged, then it is in one of the trailer's circuits and you'll probably have to rewire them. If there is more than one circuit you could isolate the problem by disconnecting one circuit from the trailer's circuit box (with the main power cord unlugged, of course!). Plug the main cord back in and check the outlet of the circuit that is still wired up. If it is okay - the problem is in the disconnected circuit. If not, it is in the still connected one. (If there are more than 2 circuits you'll have to disconnect them one at a time, checking the still connected ones at each step.)
If you decide to give this a whirl - remeber that the power should always be off & you'll be safe. Good luck!