Q: What is a Surge Suppressor?
A: A surge suppressor stop excessive voltage from coming down the wire to your RV.
Q: What is an EMS?
A: An Electrical Management System or EMS is a step up from a surge suppressor.
Q: Why would I want an EMS instead of a surge suppressor?
A: An EMS and surge suppressor both stop voltage that is too high from coming down the wire into your RV. The difference is an EMS will also stop voltage coming into your RV is it gets too low. Low voltage will possibly ruin things like motors on your furnace, air conditioner, etc. If you can afford the extra cost of an EMS, then get that. Some RVs come with internal EMS built into it, if yours doesn’t then you can purchase an external one.