Installing 50/30 Amp Service on Acreage.....?

My suggestion, use the pedistals you are talking about but run separate circuits to each outlet. If the runs are 75ft or less use#12 wire on the 20A circuits, 1 ea bulk, why, & green wire per circuit. For the thirty amp use #10 wire, one each, bulk, what, and green wire. For the fifty amp use #6 wire, two black, one white and one green. The black wires are your hot legs, the white is neutrals and green is ground. With the #6 wire you can just use all black then using electrical marking tape wrap both ends of one black wire with white tape one other wire with green tape. Make sure to wrap the wire far enough to get the green and white back into the.conduit so someone after you will know what the wires are. By doing this you get the full amp load from each receptical. If you are going over a hundred feet with all the circuits go up one size in your wire. 12 = 10'. 10 = 8, & 6= 4, this will account for voltage drop at the greater distance. All wires to one pedistals can be run in the same conduit, check with an electrician for the correct conduit size.

Sam Spade wrote:

D.E.Bishop wrote:
Isn't the typical 50/30/20 amp pedestal intended to service one site and not to do double or triple duty serving more than one site?

Yes absolutely not.

It would be interesting to see what the rating is on the breaker back at the distribution panel.
I'm betting on twin 50's.

Pedestals nowadays are typically loop fed from one to the next and the feeder between them is sized according to demand factors in the NEC. In the olden days, they used weatherproof panelboards distributed around a CG/RV park with a 30 amp sub-feeder cable to individual pedestals in a radial fashion. The old way is not as efficient as loop feeding multiple pedestals on the same feeder plus can result in excessive voltage drop. You can have say a 300 amp breaker feeding a number of loop fed pedestals. I can't recall the max. number of pedestals on a loop-fed run, but I think it's something like 8 at 50 amps. Pedestals are available with min. 70 amp up to 200 amp mains ratings. Pedestals can be configured in a number of different combos of 30 & 50 amp recepts. All pedestals are required to have a 20 amp recept.

Many good replies so far. Last year we installed a 100amp system to do just what you're asking. We have 2 trailers which use 50 amp and 30 amp respectively. After extensive research I purchased aluminum wiring, due to the cost of copper, rated to my needs and a dual 50/30 box (Connecticut Electric CESMPSC75GRHR 80-Amps/120240-Volt Circuit Protected RV Power Outlets.) I did all the work myself and ran the cable inside 3 inch PVC conduit but had an electrician do the final connections in my panel and to the new RV box. Easy peasy...

I liked the RV box because it's prewired so there's no magic in getting the wires powered correctly for an RV. Attach the feeds and the box splits it up accordingly.

Wiring in RV parks has to comply with NEC article 551. Load/demand and demand factors for pedestals is covered in article 551.73 This is for RV parks. The first recept. requires a 100 percent demand factor, two is 90 percent and so on. A 50 amp recept. has a 9600 watt demand, but this only in an RV park. A pedestal (for one site) with a 30 and 50 amp recept. would have a demand based on the 50 amp recept. only, not both. The NEC is woefully behind on RV demand today due to all the 50 amp RVs that people are buying. Only 20 percent of an RV park is required to have 50 amp pedestals. Voltage drop is a common problem as a result.

Providing receptacles for RVs in a residential dwelling is different and there are no specific rules for RV receptacle demand or multiple RV recepts. AFAIK, NEC article 220 would be used (and possibly one of the other articles?) and a load calculation (for main panel/service) has to be based on the amp rating of the load service (ie., no reduction allowed for demand factor). For a 50 amp recept., this would mean a demand of 12,000 watts. This can have a big impact on the size of a main panel (if complying with code). A 30 amp recept. at a home is usually not an issue due to the smaller 3600 watt demand. I am not sure if there an allowable demand factor reduction for multiple RV recepts. when the total load of them exceeds a certain KW amount (could be 10KW?).

Demand factor for a 30 + 50 amp pedestal may very well have to be based on 3600 + 12,000 watts regardless of how low you think the actual demand in the RVs will be. This can result in a lot of cost for the copper for the feeder cable and some or which will not be utilized (due to unbalanced load). Being able to use the 30 and 50 amp recepts. in a pedestal is not the issue, it's the feeder and beaker size in the house panel that is.

You do not have to use an RV park type pedestal. You can use a standard raintight PVC box and the correct RV configuration recept. and mount them on a wood post. Should also use a disconnect switch at the recepts. in this case (motor/HP rated).

Sorry, but "your" electrical engineer is off-base. You need to hire either an engineer or qualified electrician to do the demand calculations and size everything. I think you should think carefully how much power you actually need on the 50 amp recept. while parked at home. Do you really need two ACs, or even one? What other higher demand appliances do you think will also be running in addition to AC units? It might be that a 30 amp, 120 volt recept. will be okay or maybe install a 2P-30 amp (240V) breaker in the house panel instead of 2P-50A. Don't forget to consider voltage drop from the house panel all the way to the panel inside the RVs. I'm an EE but not only have I been retired too long and not on top of things anymore, I was raised on the CEC not NEC. But I do know enough about the NEC and RV requirements that you need to hire the right electrical expert on this. There is also the Mike Holt electrical forum if you want to ask experts there. You don't want to end up making costly errors and you need to ensure it's a safe installation.

D.E.Bishop wrote:
Isn't the typical 50/30/20 amp pedestal intended to service one site and not to do double or triple duty serving more than one site?

Yes absolutely not.

It would be interesting to see what the rating is on the breaker back at the distribution panel.
I'm betting on twin 50's.

Isn't the typical 50/30/20 amp pedestal intended to service one site and not to do double or triple duty serving more than one site?

I know it must have been done somewhere that one pedestal serves more than one site, but with 60K miles or so traveling around this country I haven't run into one. If this pedestal is strictly for personal use and you are careful, it might be okay but I don't think it would meet code nor be satisfactory for commercial use.

I wouldn't be happy sharing a pedestal with someone that has a 50 amp RV and running two ACs while I'm running my single AC. Something is going to happen there. I agree with wa8yxm, No.

You can show this pictorial to an experienced Electrician and he will understand what is needed...



Then using the MULTIMETER you can measure each of the electrical connectors to get these exacting readings...

For 50A Service


For 30A-20A Service


The RV requirements deal with the NEUTRAL and GROUND differently than the HOUSE WIRING is done... Doing the RV side like the HOUSE WIRING is done will absolutely end up burning out many APPLIANCES. So if you are using a qualified Electrician be sure he is BONDED so his insurance will cover your loses when he wires it up like a HOUSE WIRING project... Make all of this known to him up front and you should be OK... This could easily be a $5-10K dollars mistake...

The 30A wiring is really the one that trips up the Qualified Electricians... Be sure to show them this pictorial...



Note how the HOT pins are wired different for RV verses HOUSE wiring details...

Just saying
Roy Ken

Better to install four boxes for four RVs. Just set up 2x 50a and 2x 30a and pull separate wire for each. Skip the combo boxes and just get simple 50 & 30 outlet box. Let them use an adapter if the wrong RV shows up. Double check your voltage drop calculations based on distance.

Can you hook up both a 50 and a 30 amp (And a 20) on the same pedestal at the same time?

Well, it depends.. on two things.. The branch breaker in the main power distribution panel and the wires from there to the pedestal.

If the wires are rated for 80 amps. and the breaker is 80 amps, and the 30 amp outlet and 20 amp are on differnet legs (How I'd wire that box but do check)

yes, you can

The RV park where I am each site has a 50 amp breaker back in the master panel. SO here.. NO.

I am not an electrical expert and never have claimed to be but this I do know; before you hook anything to any of the RV outlets a thorough test should be done to ensure they are done correctly as more than 1 (in fact many) professional electricians have done RV outlets wrong resulting in damage to the RV.