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#161285 - 04/01/07 10:11 AM R.V . Park Calculations  
Yoopersup  Offline
Member
Joined: Mar 2003
Posts: 831
Michigan
7 sites on a Feeder in a RV park with a (Total of 35 sites in the park.) This feeder has 9600VA then 80ft 9600VA then 80 ft then 5 3600VA sites each 100 ft apart then 100ft to the breaker . Alum. wire.
9600-80' 9600-80' 3600-100' 3600-100' 3600-100' 3600-100' 3600-100'feeder brk 100'
Alum wire Question size of wire , Size of Feeder Breaker? Checking myself here.
Breaker to last site 680 feet.
Thanks Guys The Yooper


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#161309 - 04/01/07 03:49 PM Re: R.V . Park Calculations [Re: Yoopersup]  
Yoopersup  Offline
Member
Joined: Mar 2003
Posts: 831
Michigan
No one wants to take a Crack at this one????


#161313 - 04/01/07 04:04 PM Re: R.V . Park Calculations [Re: Yoopersup]  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Ernie- I don't understand the problem. Maybe you could word it a little differently and I'll take a crack at it. What are the actual loads at each site and how lond are the runs? Maybe it's just me but I can't follow you. Sorry.


George Little

#161316 - 04/01/07 04:19 PM Re: R.V . Park Calculations [Re: George Little]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,126
Estero,Fl,usa
I think the problem with RV parks is the load changes every time they rent a spot. When I was still looking at these with state they had times when all the spots were using an appreciable portion of the allotted 50a. They originally assumed 50% but that was not a good number on a hot night when these land yachts had both A/C units going full blast and every light, TV and other doodad on.


Greg Fretwell

#161324 - 04/01/07 05:19 PM Re: R.V . Park Calculations [Re: gfretwell]  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
The size of the breakers is quickly determined by 551.73.

Figuring conductor sizes to compensate for voltage drop gets more complicated.

IMHO this is a time when I would figure voltage drop assuming 100% loading of the feeders.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#161329 - 04/01/07 06:39 PM Re: R.V . Park Calculations [Re: iwire]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,126
Estero,Fl,usa
I see where he is going now. The state was too dumb to actually adjust the size of the feeder as they went along.
This is something you could plug into an excel spread sheet and tune for load any way you want. Maybe Steve has something.


Greg Fretwell

#161332 - 04/01/07 08:11 PM Re: R.V . Park Calculations [Re: gfretwell]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,126
Estero,Fl,usa
How did you get the loads? is the 3600 a 30a @ 120? That will change things a little. Putting the big loads at the end will cost you too. I am guessing 120v spots at 30a and 240v spots at 50a (using 40 for the load calc).


Greg Fretwell

#161333 - 04/01/07 08:58 PM Re: R.V . Park Calculations [Re: gfretwell]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,126
Estero,Fl,usa
OK Yooper, here you go. If you start out with a 150a breaker the smallest wire will be 3/0 al. Use that for the first 80' hop from the end. You drop .8 volts. Then go 4/0, 4/0 4/0 for the next 80 and two 100' hops. That drops 1.2, 1.9v, and 2.2v respectively.
Then use 250MCM for the next two 100' hops dropping 2.1 and 1.7 respectivly. Run 350MCM back to the losd disconnect for another 1.9v.

I think that is 11.8v or just a shade under the 5%.


Greg Fretwell

#161335 - 04/01/07 09:20 PM Re: R.V . Park Calculations [Re: gfretwell]  
Yoopersup  Offline
Member
Joined: Mar 2003
Posts: 831
Michigan
The 3600 watts comes out of the code book,see 551.73
Thats about what I came up with. I just wanted to make sure. The owner wanted the same size from start to finish so I went with 300 mcm in my Calcs.


#161358 - 04/02/07 07:48 AM Re: R.V . Park Calculations [Re: Yoopersup]  
john p  Offline
Member
Joined: Nov 2006
Posts: 32
Bemidji,MN.USA
Its hard to find rv eguipment that you can loop any thing larger than 250's thru so use 250 mcm with a full size nutral. I use 250/250/4/0 USE direct burial and use the 4/0 as the ground, reidentify with green tape and run a single 250 with the group for the nutral and reidentify with white tape.
I would just start out with a 200 amp breaker hit a terminal box.The runs are to long to just use one feeder. so break it up and run multipal feeders from the terminal box.you may have to run a feeder all the way to the farthest pedistal just because of voltage drop. I hope this helps.

John P


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