Generator Size for Three RV's

[dadgumitjimbob]

Hello,

We have a spot on our farm that we would like to setup for three campers. We are wondering if we could buy one generator to power all three.

One is a 50 amp with two A/C's
Two with 30 amp and one A/C

What size generator would we need? I'm not an electrician and I didn't stay at a Holiday Inn Express last night, but if the normal size Gen in most RV's is 4000 watts, wouldn't a 15,000 watt Gen cover them all? Again not an electrician, so I'm sure there are some complicated calculations to figure this out.

Thanks in advance for any help!!!

[NinerBikes]

I'd tell them to all camp somewhere else, unless they are footing the bill for all it takes to get electric in there. Why don't they all go buy their own EU3000I's and the big dog with the 50 amp job sort it out himself?

[BurbMan]

I would have utility drop a separate 200a service. What about water, sewer and cable TV?

[Salvo]

I agree. Instead of going worst case and adding all max currents together, I would RSS (Root Sum Square) them.

That means:

I = square root(100^2 + 30^2 + 30^2) = 109A

Power = 109A * 120V = 13 kW

15 kW should be fine.

Chris Bryant wrote:
A 15KW will be fine- people rarely use the full capacity of their electrical system. I've run 10 rigs off a 30KW genset with regularly with no problems.

15 KW is actually more power than I have ever used in my all electric house and shop, with several rigs plugged in.

[Peralko]

Another issue not mentioned is that the generator has to be capable of putting out 240 volts if you want to furnish 50-Amp RV service. As mentioned 50-Amp RV service is two legs of 50 Amps with 240 volts between the legs.

[Chris_Bryant]

greenrvgreen wrote:

For three RVs, I would get three or four of the Champion 3500/4000 watt gennies. Same total amount of power, but now you're not driving all that iron just for the little stuff. In the morning and overnight I would only run one of them and make everybody share, or make them buy the fuel.

A big diesel is far more fuel efficient than the small sets-I could run my 30 kw set with its Cummins 4B and use less fuel than my Onan 4kw- just over 1 gallon per hour. Those small sets are so inefficient it's not funny.
Looking at new Chi-com diesel sets, you can get 15kw for about 1 gallon per hour- full load.

[greenrvgreen]

My reading of the OP is that these spots are for family or friends, so I would assume some measure of co-operation on electric use could be expected.

Like others said, I would investigate the cost of stringing utility electric to your site. When I inquired I would not mention the RV spots, but only ask about residential service, say for a future home--in case there are any fed subsidies available.

I would not go at this with a single generator under any circumstances. If you size a single gennie for your peak power needs you will be burning maximum fuel even when one RV is hooked up with only reading lights.

For three RVs, I would get three or four of the Champion 3500/4000 watt gennies. Same total amount of power, but now you're not driving all that iron just for the little stuff. In the morning and overnight I would only run one of them and make everybody share, or make them buy the fuel.

Since a member of the Noise Police has already chimed in, I would mention that you want these gennies as far away as possible, and with a decent wall or berm between you. That means you're stringing a lot of costly wire.

I ran a pair of Champions for a week straight during a power outage, and even though I love and defend the Champ, by the end of the week my head was throbbing from the constant drone.

[MEXICOWANDERER]

Having a Kubota with one the last 12 turn 12.5 KW Katos ever made, I don't know if your accountant's hat is sitting square but you may be looking at 20 - 30 gallons of diesel per day. Run time between oil changes, varies, but I use a C750L Luberfiner soot removal bypass filter and an adapter fitting for a Baldwin B88 oil filter for an 855 Cummins. All done to reduce soot buildup in the oil and maximize runtime between oil changes.

No matter how I run the numbers what you are looking at is going to be insanely expensive/a horrible maintenance-time-eater and a potential land mine in customer relations with RV space renters. It just does not fit.

If your spaces are within reasonable distance a pair of three phase 240 to 600 volt transformers, overhead poles and lines, aluminum conductor, then a Scott Connection transformer on the RV end would be the most cost effective. Set concrete 7 meter poles with vertically oriented insulators 24" spacing. The separate Scott Connection transformers (one tickler) will convert 3 phase to single phase 240, or you'll never balance phase load (school of the hardest generator knocks). I did four multi-RV commercial installations in the Sierra Nevada mountains at summer resorts, including the engineering studies, only the installations were not commercial power but gensets remotely located because of noise and fume isolation. The gensets powered resort stores, and utility services as well.

Running overhead lines, you have to incorporate lightning protection, no matter what the power origin, commercial or private. You have a big job ahead of you.

The Walker Lake project used LPG fuel, one Wisconsin 37.5 HP V-4, with an Onan 15.0 KW backup. Even 30+ years ago, this larger project LPG 24 2-volt cell batteries and twin Trace 5548 inverters consumed more LPG fuel than I would ever care to deal with. The owners were always complaining about fuel usage.

Best of Fortune to you

[mena661]

imadtchmn wrote:

I always thought the 50 amp service was two 30 amp legs and two grounds, not two 50 amp legs. I've lost my mind and still trying to find it.

Nope. Two 50 amp legs at 120V each (220V total).

[WayneLee]

I have a friend that has a remote ranch. He chose to use a 15KW LP generator. He decided to use LP since he gets regular deliveries by his LP supplier already for heating, cooking, etc., so he just added another tank to fill.

[imadtchmn]

Bobbo wrote:

naturist wrote:
No, the computations are pretty simple. 50+30+30=110 amps. At 120 volts, that would be 120 x 110
= 13200 watts, so yes, a 15,000 watt generator would cover you.

I agree with the earlier posts that the 50 amp rig is 2 legs of 50 amps each, so the math is

(50+50) + 30 + 30=160amps = 19,200 watts.

You can get a generator smaller than 20,000 watts continuous duty, but remember that you won't be able to run all 3 RVs at full capacity at once. Few 50 amp RVs run at full capacity, but many 30 amp RVs do, or nearly so.

I always thought the 50 amp service was two 30 amp legs and two grounds, not two 50 amp legs. I've lost my mind and still trying to find it.

[Bobbo]

naturist wrote:
No, the computations are pretty simple. 50+30+30=110 amps. At 120 volts, that would be 120 x 110
= 13200 watts, so yes, a 15,000 watt generator would cover you.

I agree with the earlier posts that the 50 amp rig is 2 legs of 50 amps each, so the math is

(50+50) + 30 + 30=160amps = 19,200 watts.

You can get a generator smaller than 20,000 watts continuous duty, but remember that you won't be able to run all 3 RVs at full capacity at once. Few 50 amp RVs run at full capacity, but many 30 amp RVs do, or nearly so.

[n7bsn]

So the generator would run $3000 to $5000, depending on size and maker.
Plus install (unless you are really good at DIY)
Plus a fuel costs, this type of install is usually propane for a reason.

VRS
Having the power-co bring in power and paying them for the power.

I'm going to guess, that unless the pull is over a mile, the power-co is going to be cheaper, both in the short and long run.

[Chris_Bryant]

A 15KW will be fine- people rarely use the full capacity of their electrical system. I've run 10 rigs off a 30KW genset with regularly with no problems.

15 KW is actually more power than I have ever used in my all electric house and shop, with several rigs plugged in.

[MrWizard]

50 amp service is really TWO LINES of 50 amps each
So it's 160 amps total, need a 20kw generator
Me.. I would install a 15kw, and Three 30 amp outlets
Everybody can be equal, and the big rig will just have to learn power management
The extra watts from the generator will provide some overhead, and nobody will have low voltage , nor will the generator struggle when somebody turns on the MW while the a/C is on
He might trip his breaker, but he won't bother the generator