Electrical Design for an RV Park

[UFGatorEE]

Hello all. I am new to the forums but have come here many times in search of NEC code interpretations and help on design related issues. I have a specific problem I am trying to work through at this moment and need some guidance.

I am currently working on the electrical design for an RV park (30 RV sites, 4 tents sites, service voltage 240/120V single phase). A little background is necessary to understand the magnitude of my problem. We received this job as a result of a botched design build attempt of an inexperienced contractor, meaning the sites are already set and the main distribution panels are installed. The contractor ran #12 copper conductors to every site from two panels located side by side in the concession/restroom building by the parking lot of the park. Also, he terminated the conductors at waterproof quad receptacles at the RV site posts, so all of the RV sites are 20 amps only. To summarize, he has improper hardware at the sites and the owner is experiencing herendous voltage drops at the majority of the sites.

I have laid all my sites out, having two 50 amp sites and twenty eight 30 amp sites, per NEC artcile 551. However, I am running into the same issue the contractor had, my voltage drop calculations at the majority of the sites are ranging between 8% and 15%. I am toying with the idea of dropping a couple pole mounted panels in two or three different places throughout the park and subfeeding them from the main panels to cut down on these drops.

Has anyone ever designed an RV park electrically before? If so, how
did you tackle the voltage drop issue?

 

[bdarnell]

Welcome to the forum. It was a pleasure having all of the Gators in Indy this past week for the Final Four. Congrats on your 1st NCAA Championship!

On to the question. You do have you hands full, don't you ? I have designed a couple of KOA's in the past, but it's been a long time. As I remember, we used a couple of distribution centers to cut down on voltage drop issues, just as you mentioned. We ran a lot of aluminum URD to the sites and the minimum as I recall was #2, even for a 50 amp site. We used 400 amp distribution centers and our goal was no more than a 3% drop at the distribution center.

Break it down into segments and it gets easier. Like I said, we used aluminum and that helped with the cost issue a little.

 

[don_resqcapt19]

There are pedestals available where you feed in and out with large conductors and the site breaker is tapped from that terminal block and feeds the site receptacle. Some of them have loop feed lugs for 350kcmil.
Don

 

[bdarnell]

Don is right on track. Midwest makes such a pedestal.

Find them HERE

 

[iwire]

I have never been involved with wiring a RV park but I find these discussions interesting when they come up.

I have to imagine that the RV park developer has no idea what kind of money the electrical is going to cost and has a coronary when the bids from legitimate contractors come in.

The service calculations get big quickly and the fact you must distribute 50 amps or 30 amps far distances at low voltage has to make the conductor costs extreme.

 

[jtester]

I've done a number of RV parks, and voltage drop is always a problem. First though

I have laid all my sites out, having two 50 amp sites and twenty eight 30 amp sites, per NEC artcile 551.

My NEC requires 20% of the sites to be 50 amp, you have less than 10%. After you resolve that, I agree with Don and Bob, I often run 200 amp feeders and tap into pedestals that have either 30 or 50 amp breakers.

Jim T

 

[UFGatorEE]

Thanks all for your replies. They have been helpful. One last question for those of you who have worked on RV Parks before. Are direct burial conductors (Type UF) permitted to be used? I was planning on using this type of cabling and simply running them to a rigid metal conduit elbow at the sites. Then it will be enclosed in rigid metal conduit up to the box. Code states in article 551-80 (b) that conductors only need to be protected when entering or leaving a trench. Am I interpreting this correctly?

 

[tshea]

Here's another idea for an RV pedestal http://www.milbankmfg.com/images/rv_pwr_outlets/u5000.htm