RV Park pedestals

[Electron_Sam78]

I took an electrician position at a local lake and will be taking care of the electrical equipment within campsites/RV parks. I need to brush up on load calculations and stuff in case we need to rewire some site loops. How do I do load calculations to determine feeder size? For example let's say there are 3 park loops with 15 RV sites each. The pedestals each have 1 50a RV receptacle, 1 30a RV receptacle, and 1 20a GFCI duplex receptacle fed from a 50a, 30a, and 20a circuit breaker (at the pedestal) respectively. I need to know how to calculate the feeder or the service (I'm not sure how it's set up yet) for the load center supplying the loops. I think right now they have 3 or 4 pedestals per 100a CB in the load center. I want to check the math, NEC articles on this setup.

 

[barbeer]

Article 220 would be key.........550 may apply depending on your park.

 

[Electron_Sam78]

Actually it's 551 for RVs/ parks. 550 for mobile homes/parks. Does anyone have experieince laying out the electrical distribution for an RV park? Here's one of 4 of my RV Parks: http://www.mvs.usace.army.mil/rend/Maps/MarCamp.html

 

[augie47]

Actually it's 551 for RVs/ parks. 550 for mobile homes/parks. Does anyone have experieince laying out the electrical distribution for an RV park?

more than I want :smile:

Here's one of 4 of my RV Parks: http://www.mvs.usace.army.mil/rend/Maps/MarCamp.html

You will need a list of exactly what receptacles are available at each site (551.71 will gibe you the minimum requirement) and then follow 551.73 for demand.
If, as you say, you have 4 pedestals, each with a 50 amp, the 100 amp breaker would be a bit undersized. (If I did my math correctly it would require 120 amps)

 

[Electron_Sam78]

As you can see the campground has nearly 150 sites, all with electrical power. I'm wondering do you apply the demand factor when detrmining the service for all of them from the POCO transformer and then again at each distribution panel? For instance the 147 sites multiplied by 9600VA = 1,411,200 then divided by the demand factor of 41% = gets a 2,646 amp service requirement for the park- just the RV sites alone not including the buildings. When I calculate again for the individual loops do I apply the demand factor again to distribute the 2646 amp service to several panelboards which will feed the individual loops through branch circuits? Or does the demand factor only get applied once for the total service?

 

[augie47]

my opinion would be that you look at it as two situations. Use the demand factor for each feeder then, forget the individual feeder loads and use it for the service adding the total pedestals.