2 RV's on One Electrical Post

[DearMissMermaid]

Many electrical posts come with 50 amp and 30 amp outlets.

What happens if 2 RV's are on the same spot, can they both plug in or will they each have to load share the power?

 

[docj]

I'm not an electrician, but I believe that if a pedestal provides 50A, 30A and 20A outlets then in accordance with the National Electric Code it ought to be wired so that all of them can be used at full power at the same time.  I wouldn't bet that all RV parks are wired this way, but I believe they are supposed to be.  So if 2 RVs shared one pedestal one could have 50A power and the other 30A.

 

[John From Detroit]

Depending on the park.. If it is properly wired.. Everything works (Odds low) if the wires to teh pedistal are a bit anemic (odds high) then everything from low voltage to burned neutral (Why is it always the neutral?)


And in some parks.. A not so polite invitation to park elsewhere (Different RV park) as many have a rule against that.

In some parks however, one box is shared by as many as four sites... I might add,, these are usually short on power

 

[SeilerBird]

I would think the odds would be against the box working properly if the 50, 30 and 20 amp loads were being used to the maximum. So theoretically it would not work because the pedestal would have to be fed with wire that could handle all 100 amps. I doubt most of the pedestals are fed with wire that will handle 50 amps. However, in the real world very few people are running their RV anywhere close to maximum load so it would probably hold.

In other words a 50 amp RV is rarely running over 20 amps load at any given time. It would be hard for three RVs to max out a 100 amp wire.

 

[glen54737]

Generally you could use the 50a or the 20a and 30a but not all three together.
The feed coming to the post is 50a 220v normally.

John the neutral takes the hit because it's 2 power leads and one neutral of the same size to carry the load. It's not "in phase" but is close enough that it is overloaded.

 

[Wizard46]

Nothing in electrical code says all should or could be used at full amperage. Think about your home, you will usually have several 15Amp outlets on one 15Amp breaker. If you plug in several 15 amp devices you will most definitely trip the breaker.

 

[Gary RV_Wizard]

Wizard46 is correct - at most the NEC requires a sustained 80% of the peak rated load for any given device or circuit. Nothing in the NEC requires that the three outlets in the pedestal all actually operate at their max rating simultaneously. The code requires that the components be able to safely handle their rating, but not that they actually provide the full rated power.

The supply circuit has a rating too, and that would typically be 50A/240v.  I've worked in several RV parks and have done electrical maintenance in two of them with 50A pedestals and both of those were limited to a 50A/240v feeder to the pedestal. The standard wiring in a pedestal box with 20/30/50 outlets has a 50A/240v feed to the 50A outlet and the 30A & 20A outlets are tapped off one leg of the 50A feed. That complies with code because it handles the anticipated max load and the supply breaker trips if the anticipated load is exceeded.

A common example would be the convenience outlets in a home. Typically several 15A outlets are daisy chained on a single circuit, which is also rated at 15A.  If any one outlet is delivering 10A, for example, the others are limited to a combined maximum of 5a because the supply breaker won't allow more than 15A total. That protects the circuit wiring and every individual component of the circuit - the total can never exceed 15A.

 

[docj]

It turns out that the National Electric Code has a whole section on RV park wiring.  Here's an excerpt from a discussion of wiring 8 new outlets in an RV park:

A 30/50 amp RV load is calculated at 9600 VA per site. Also with up to 8 sites your demand factor is 55%. This means that 9600 VA X 8 = 76,800 VA. This breaks down to 42,240 VA or equivalent to about 176 amps. Based on a single phase 120/240 service.  So you could put all 8 on a 200 amp breaker in an outside panel.  In this example the circuit was wired with 4/0-2/0 URD cable (underground aluminum cable) which is rated at 225A.

The 20/30/50 pedestal is wired assuming a load of 9600 VA (which is equivalent to 80 A at 120V).  So the assumption is made that the "average RV" on a 50A breaker uses ~80A.  But what really matters is that multiple pedestals themselves are protected by circuit breakers.  So at a park that is wired in accordance with NEC using the pedestal to its maximum isn't going to cause a real problem unless everyone else is using their pedestals at the design current (80A) in which case the main breaker could trip.  Probably not a very likely occurrence.

 

[Bill B]

Doc's got this nailed ---except, The neutral is also allowed to be derated more. Remember that it is carrying the unbalanced load.

Now to play the what if game. Many of the bigger coaches come with inverters, which will run most everything in the coach. All coaches will run off 30 amps (not everything (second air) but the "normal" stuff.

I've never done a survey, but I would bet a coffee that 95% of most everything in the coaches are all wired to L1 side of things.

And I would throw in a donut and say that most of the parks are wired the same way.

So, most of the load is on the L1 (in the trailer, MH) and the neutral (undersized - legally) in the pedestal, hence your neutral "problems". I flipped the power wires in our coach (L1 and L2) and played (built my own adapter) with the cord, and we seem to have a lot less power problems than other people. But then, I tend to monitor things and

 

[tvman44]

If wired properly, no.  Some parks cheat and take short cuts to save money then the answer is yes.

 

[John From Detroit]

True story... Park I am in just now lost around half a dozen sites to an open neutral a few years back.. I assisted slightly in the burying of the new wire.  (Basically I helped hold the boxes straight while the crew taped dirt around them).

I looked at the wire the manager buried to feed those boxes

They can take it, and likely that much more.. I said to him: "do not want to have to do it again do you" and he said "NO"

Next week,,,, Not only did he have to replace one run of the wire, but a sewer pipe too as a long term camper (Some sites here still have over 60 years left on the lease) drove some REBAR into the ground to anchor some Rail Road Tie borders.

Right into the wire  and the brand new sewer pipe.

 

[Gary RV_Wizard]

I've never done a survey, but I would bet a coffee that 95% of most everything in the coaches are all wired to L1 side of things.

How do you measure the 95%? Quantity of outlets and appliances, actual amp load, or max amp load? My 50A coach has the water heater, washer/dryer and rear a/c on L2. If they are all running, they pull about 40A, which is roughly what the amp load is on L1 with a lot of stuff running. But I average a higher amp load on L1 than on L2. Typically (on a hot summer day) around 24A on L1 and 12A on L2.

 

[Ned]

Our loads are balanced very well on the two legs:

L1 has Rear A/C, Inverter, Block heater
L2 has Front A/C, Refrigerator/Bedroom outlet, Water heater

The inverter circuit has most of the outlets on it.

 

[John From Detroit]

I've never done a survey, but I would bet a coffee that 95% of most everything in the coaches are all wired to L1 side of things.

Humm, let me look.....

On my house even number breakers are L-2, odd L-1 by default. Mains are breakers ZERO for this list

Breaker 1: (dual half size) Rear AC and 20 amp outlet (for heaters when I do not need A/C)
Breaker 2: Xantrex Prosine This covers Televisions et-al, Microwave and GFCI chain
Breaker 3: Water heater
Breaker 4: Front AC
Breaker 4: One of the two TT-30 extension outlets I added and the washer (I use it for a 2nd space heater since I do not have a washer)
Breaker 5: The other TT-30 and another HD outlet for another space heater
Breaker 6: no connection
Breaker 7: Bedroom outlets and Converter (1KW load)

Looks fairly balanced to me

Now I added two drops and the two HD outlets.

Camping world added (And screwed up) the Xantrex (they put both A/C's on the same leg, Damon originally had 'em split)

A lot depends on which technician wired it I suspect... As I said, I re-balanced after CW messed it up making sure the two A/C's were on different legs and splitting between the Water Heater and Prosine (MIcrowave, TV and GFCI chain).

I added 4 outlets 2 TT-30 one on each leg and two 15/20 for heaters one on each leg.

The Frige is on the bedroom loop.. Which by the way can be MANUALLY switched to the inverter (Prosine) output if I choose.. I do this when I want power to the bedroom outlets when boondocking after locking the fridge on GAS.