Although we haven't stayed in many RV parks, most of those that we have stayed in had very low AC voltage. One park was down to 98 volts, which will cause damage to the Air Conditioner and Microwave if ran at this low voltage. Due to problems encountered, we purchased a portable 50 amp Autoformer by Hughes. When the RV park power drops below 117 volts, this electrical device boosts the voltage up to 10%. It does this by lowering the amps. Once the RV park power returns to 118 volts, the Autoformer just lets the power pass through without any boosting. The built in grounding continuity test offers protection against damage from open ground, open neutral or reverse polarity. All considered, this device protects the RV electrical system from brown-out damage.
Normally, your RV power cord plugs into the Autoformer, and the Autoformer plugs into the park power. The Autoformer has a handle to chain it to the RV park power pole. Besides worrying about a $400+ device being stolen, who wants to lug it back and forth every time we hooked up. Some people have hard-wired their Autoformer into their RV, but this makes the installation more permanent. In case of problems, or if I sold the RV, I still wanted the Autoformer to be transportable. My answer was to make it portable, but located inside of the RV instead of at the power pole. This simply involved:
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Removing the RV's 30 ' 50 amp cord from the RV and replacing a female plug on one end. A male plug is already on the other end. An alternative would be to remove this cord and just buy a 30' 50 amp extension cord. But at $150+, I decided to modify the existing cord. If your rig is like mine and has 50 amp service, be sure to ONLY use a NEMA rated 14-50P (plug) and plug into a 14-50R (receptacle). If your RV is only 30 amp, use standard (ANSI C73.13) or NEMA TT-30P (plug) / TT-30R (receptacle).
.jpg "The cords")
.jpg "Internal Installation")
- Installing a short, 2' (or 3') cord with a male plug at the same location you just removed the 30' cord. This is where power goes IN to the power breaker box.
The parts used are NOT CHEAP. One plug may cost around $40! Luckily, besides the Autoformer, there were only three parts I needed to purchase. 1) The Female 14-50R (I found an affordable one at Home Depot for $15), 2) the Male 14-50P (I had to go to an electrical supply store for this - $$$), and 3) a couple feet of the flexible, 4-wire cable. I asked for 50 amp cable for a manufactured home. Besides the Autoformer, my total cost was around $50.
As this picture shows, the Autoformer fit in nicely in my electrical 
compartment. You can see the Autoformer tucked away in the back, with the 30' RV cable plugged into the generator. You can't see the other end of this 30' cable, which is plugged into a short cable with a female receptacle which comes attached to the Autoformer. You can also see the new, short cable plugged into the Autoformer, which is going onto the RV breaker box. This places the Autoformer in the path from the power source (park or generator) to the RV.
<.jpg "Bypassing the Autoformer")
This picture shows the Autoformer being bypassed. If needed, I could remove the Autoformer completely from the RV now. You also see the short input cable plugged into the female receptacle of the 30' cable. The other end of the 30' cable would be plugged into the RV park power, or the generator (I don't have an automatic power switch - I manually move the cable as needed).
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