Power control system by Precision Circuits Inc
So I learnt sumthin today. Surprised even me :=) We arrived at the campsite and it was advertised as a 30 amp site. I was surprised to find 50, 30 and 15 amp outlets with associated sized circuit breakers. So I counted myself a lucky man and plugged directly into the 50 amp outlet. My Progressive Industries EMS indicated 126 VAC on L1 and L2 and 0 errors. Sweet! I proceeded to turn on the AC breakers in the coach. Being the OCD nut job that I am, I did not turn on any breaker whose connected appliance I was not going to use. Ran both AC's all night and got it meat locker cold in the coach! I forgot to mention that we are in Alabama where the Devil hangs his nether regions, so hot and sweaty, YEP!
Got up this morning and decided to do some laundry. I turned on the breaker for the dryer, washer, and hot water heater. The Precision Circuits Power Management System flashed on and indicated 30 amps then promptly cut off my life sustaining air conditioning. I thought, what the heck! I turned the dryer, washer, and water heater breakers off and the PCPMS promptly indicated 50 amp service and went back to sleep. 2 minutes later the AC came back on.
Long story short. Even though the pedestal outlet was 50 amp and the breaker was 50 amp for that outlet it was not 50 amp service but 30 amp service. How did I figure this out? I read the manual for the PCPMS. It stated that the way it determines if you have 30 or 50 amp service is by measuring the voltage between L1 and L2. If 50 amp then L1 to L2 should measure 240 VAC. If 30 amp then L1 to L2 should measure 0 VAC. In my 2015 Aspire the PCPMS measures this at the dryer circuit and the water heater circuit. If you do not have these breakers ON then the PCPMS does not know if you have 30 or 50 amp service and cannot perform its function which is to shed AC loads when the coach is connected to 30 amp service to prevent overloading and tripping the pedestal breaker.
Hope this helps someone and is clear enough to understand.