I have a Mobile Trailer that is used as a small office and I want to install a dedicated line for a 240V electric wall heater unit, my run is 20ft from the home to the Trailer and I would be using 10 GA THHN wire along with Rigid PVC from the house to the Trailer, The box on the house will be waterproof as well as the box planted on the outside of the trailer, I will be putting the Rigid PVC 2' FT underground, I was going to use a 30amp breaker I will be running 3 wire, but wouldn't I need a GFCI Breaker for this Since going outside from the house to the Trailer or since Im going underground with this setup instead of using Uf wire that I would not have to use the GFCI Breaker.