diazr2 wrote:
You won't have to cut the main wire, inside the rig you will find the big wire connected at a junction box. You can connect the protector with the wires inside the junction box.
The OP says he has a portable surge protector so if he wants to install it inside his rig of course he will have to add connectors that will plug into his unit - one male, one female. I did just this a few years ago in my own trailer when I installed a portable TRC EMS and located it under the sofa. Since mine was a 30 amp version I used matching 30 amp TT-30 connectors, obviously those with a 50 amp version would need to use TT-50 connectors.
The only comment I would add is that hopefully when the OP said "surge protector" what he really means is he purchased an EMS w/surge protection as a surge protector alone, while useful, won't protect his rig from the many vagaries of incoming source power as will an EMS.