By Mike Sokol
Love your newsletters and thank you so much for your hard work! My wife and I have been full-timing in our 5th wheel since retiring a couple of years ago. We have a “home base” in Wesley Chapel, Florida. Our neighbor was telling me that a 50-amp service barely powers his 45-ft. Essex motorhome. He told me about this new park here in Florida that provides 100- and 150-amp service. See the link to the Keystone Heights RV resort HERE.
My first house only had 100-amp service! Is this a new trend to provide higher amp services for RVs? Wouldn’t a higher amperage pedestal require a heavier cable? Thought it might be a article that you might be interested in.
Thanks. —Bob Sapio
I believe this is a case of mistaken identity that I discussed last year. As William Shakespeare wrote, “A rose by any other name would smell as sweet,” and Shirley Ellis would write “The Name Game.” Yes, you should listen to this fun song HERE to prepare yourself mentally for this tutorial. And re-read my JAM Session on 100-amp pedestals HERE.
First things first
First of all, did you realize that a standard 240/120-volt by 100-amp service in your home is actually 200 amps at 120 volts? And a 200-amp home service is actually 400 amperes at 120 volts? So when we plug into a 50-amp campground pedestal we have to make some adjustments in the amount of power we use.
But do resorts really offer 150-amp pedestals?
While it’s certainly possible that a resort that’s offering spots for Park Models can offer 100-, 150- or even 200-amp electrical service, I don’t think there’s any RV (or even a large coach) that requires more than what a standard 50-amp pedestal can supply. And if there’s a portable pedestal to plug into, then it’s going to have a NEMA 14-50 outlet rated for 50 amps at 240 volts, which is actually 100 amps total at 120 volts. And here’s why…
Take a look at this standard 50-amp pedestal which I’ve renamed as a “150-amp” pedestal. While it certainly can’t supply 150 amperes of current on a single conductor, it can indeed supply 50 + 50 amps (100 amps total) on the “50-amp outlet,” and should be able to supply an additional 30 amps on the TT-30 outlet, plus an extra 20 amps on the 20-amp “home” outlet. Add it all up and it comes to 150 amps at 120 volts.
I have heard of a few campgrounds that call it a 100- or 150-amp pedestal, which is not the traditional nomenclature. We all call it a 50-amp pedestal, because that’s the most current at 240 volts it can supply from the NEMA 14-50 outlet. And yes, that does indeed add up to 100 amperes total current at 120 volts.
But can I get 150 amps from a pedestal?
Getting 150 amps from a pedestal is really not what these campgrounds (and the NEC) intend you to do. To make that happen would require you to connect up with three separate shore power cords (50, 30 and 20 amp), which is an NEC violation. And in any event, there’s just no way to combine a GFCI-protected 20-amp outlet with the 30-amp outlet without tripping the GFCI protection circuit.
Is this a case of mistaken identity?
I think it’s a marketing mishap where campgrounds and resorts may be offering 150 amps at 240-volt service (300 amps total at 120 volts) for Park Model Homes, but still provide the traditional 50/30/20-amp campsite pedestals – which adds up to 150 amps of current at 120 volts that you can’t really access all at once.
Yes, as noted above, a properly installed 50-amp pedestal outlet should be able to supply a total of 100 amperes of current at 120 volts, but nothing more.
Gloom, despair and agony on me?
But all is not lost. Just remember that ANY properly wired 50-amp pedestal outlet can provide 50 amperes of current at 240 volts, or 100 amperes of current at 120 volts. And since virtually all RVs (with only a few exceptions) use 120-volt power exclusively, you have 100 amps of current at your disposal, albeit in two separate circuits of 50 amps each.
I’m not sure what your friend’s issues are that’s causing them to barely be able to power a 45-ft. Essex motorhome from a 50-amp campground outlet, unless it’s totally electric with a instant-on electric water heater and perhaps electric heat. And having a 240-volt electric clothes dryer could also be part of their energy black hole. If someone from Essex wants to contact me about their power usage, I would be glad to incorporate the amperage requirements in a future article.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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Looking at the website for Keystone Heights, the Amenities page shows “100 Amp Electric,” not 150. https://www.keystoneheightsrv.com/amenities
i need 120 ampage for my park model with an addition. this is a park model with a meter that is stationary, We do not travel with it.. How can I make that happen without having to have a custom built pedestal?
Keep in mind what the circuit breakers are for – to protect the wiring from the socket out to what it connects to. Not to add up their capacities to determine what the pedestal can potentially supply – that is a bit more involved.
Mike talking about RV pedestal pwr, we use the 50a plug & at same time 20 plug for outside the MH gadgets & has always worked fine. But 1 RV park that we have stayed at 3yrs in a row the 20a gfi plug would trip the gfi. 3 different RV sites same results. Talked to park manager & says can only use 1 plug on pedestal at a time. Is he right & other parks wired wrong or is his pedestals all wire wrong?
Did you forget the %80 rule? 50 amps less 20% is 40 amps.
My neighbor has an all electric NEWMAR ( no propane at all) and works just fine on the 50 amp plug
An Essex is one of Newmar’s upper line of diesel pushers. We have one in our park and it’s uses the same 50-amp shore power cable as I use in my all-electric Allegro Bus. There have been a couple of times when cooking in the summer, where a couple of ACs, the cooktop, the convection oven, and the electric water heater have all conspired to require a little boost from the batteries/inverter when one leg of the 240 was overloaded for a few minutes.
It was that we were using more than 100 amps of 120 volts. It was a balance issue between the two legs. It has only happened a handful of times so I haven’t studied it enough to see if I need to swap breakers around to get back in balance.