RV Community Load Caculation

[DaveO]

I am looking for some help doing a Service load calculation for a 280 site RV Park. The owner wishes to install 210 sites @ 50Amps and the remainder 70 sites @ 30 Amps. There will be no tent sites. The 210 sites are for Park Model homes with all gas appliances and are service rated at 50Amps.

 

[masterinbama]

First thing I would do is talk the owner into using the combo 50-30-20 pedestals and go from there.

Something like this.


http://www.midwestelectric.com/product/rvs.htm#parkranger

 

[buzzbar]

Look at table 571.73 for the proper demand factor. With over (36) sites, your demand factor is 43%. If you have a 50A circuit at a given site, you should definitely install the 50-30-20 combo, as not all campers use 50A, or have adapters.

 

[kbsparky]

Where is this park located? In many areas, the heat waves of summer are bearing down. A fully occupied RV park would have most of the units running their A/C's full blast in this type of weather.

While it may be permissible to apply demand factors, I have seen that go out the window under such extreme conditions, and the entire park's mains tripping out from overloads.

SO be sure to allow for enough wiggle room to handle the conditions of your area when calculating your service loads.

 

[broadgage]

I would agree that in a hot area, A/C loading could be a problem, it would be resonable to assume that almost every unit will use A/C at the same time in a heatwave.

I would calculate as per the NEC, but also calculate the maximum likely load with near univeresal air conditioning.
What is the largest likely or standard A/C unit that will be used ?
Presume that 95% of the units will run the A/C at the same time (even in a heat wave, a few units will be empty, or the air conditioner not used), Then make an arbitary allowance of say 5 amps per unit for lighting and small appliances.

If the NEC figure is larger use that.
If the figure calculated on the basis of 95% A/C use plus small appliances and lighting is larger, then use that.

 

[masterinbama]

The reason I recommended the 50-30-20 at all sites is so the owner and the users weren't stuck not having the right hookups when needed. The cost of this would be minimal given the size of the job and would make keeping or getting repair parts much easier.

 

[kwired]

The reason I recommended the 50-30-20 at all sites is so the owner and the users weren't stuck not having the right hookups when needed. The cost of this would be minimal given the size of the job and would make keeping or getting repair parts much easier.

Installation is simpler too. Just run a feeder from unit to unit, all the branch circuits are done for you within the unit.



While air conditioning load will be high during heat wave, lets remember that air conditioning is not 100% of the calculated load. Air conditioning is a major percentage of load on most RV's with a 30 amp supply, but is probably only 50% max of circuit capacity on a 50 amp supply in most cases.

 

[haskindm]

Remember the NEC is a MINIMUM. Although derating is allowed, you may end up with an installation code compliant but inadequate.

 

[suemarkp]

While air conditioning load will be high during heat wave, lets remember that air conditioning is not 100% of the calculated load. Air conditioning is a major percentage of load on most RV's with a 30 amp supply, but is probably only 50% max of circuit capacity on a 50 amp supply in most cases.

Another reason to install the 50/30/20 pedestals at each spot. Calculate per the NEC with every spot as a 50A load and you should be able to handle a full park with AC units. Some of the spots will only have the 30A or 20A trailers which will offset the demand factors they allow you to use.