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#188587 - 08/19/09 01:25 PM RV Park Calculations Art. 551  
Yoopersup  Offline
Joined: Mar 2003
Posts: 822
Feeders Can be derated by number .551.73 Table.
Is it one feeder when you use pass thur lugs at each pedestial??or go by number of Pedestial?? I'd say 3 pedestails = 80% on feeder.
Also when you have 3 and use 80% do you still have to go by 125% load for continous duty??Another words (load 9600VA x 3 = 2880 x 80%= 23040 Divided by 240 = 96 amps.
then 96 x 125 % continious duty = 120 amps. I think you stop at 96 amps.
This is using Pass thur lugs at each Pedestail rated for amperage passing thru.

2017 / 2014 NEC & Related Books and Study Guides

#188589 - 08/19/09 02:29 PM Re: RV Park Calculations Art. 551 [Re: Yoopersup]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,103
This is a feeder and the pedestals are feeder taps.
I agree you can use the table as your "design guide" but do it at your peril. The guys in the Florida park system will tell you these new RVs can use a significant part of their power cord rating and when you have a full house, those tables may not get you enough power to get through the night.

Greg Fretwell

#188593 - 08/19/09 04:43 PM Re: RV Park Calculations Art. 551 [Re: gfretwell]  
Yoopersup  Offline
Joined: Mar 2003
Posts: 822
There going with 100% 50 amp plugs way over the 20% code requires. Most RV parks nowadays have 80 to 100 % 50 amp Ped. Codes way behind in the area.

#188594 - 08/19/09 07:04 PM Re: RV Park Calculations Art. 551 [Re: Yoopersup]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,103
It may not be a big issue up there in the UP but the A/C units in those big "pushers" can really drag down a feeder.
That seems to be the biggest single addition to the load in an RV park. Lights and TVs are minimal, "heating" appliances are usually gas.
It is when you have a hot night and every buttons up and turns on the "air" that voltages sag.

Greg Fretwell

#188595 - 08/19/09 08:17 PM Re: RV Park Calculations Art. 551 [Re: gfretwell]  
renosteinke  Offline
Cat Servant
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
My experiences this past year suggest that this is an area that really, really needs to be addressed- by code panels, code enforcement, and park managers.

Power runs that usually have no problem supplying a dozen spaces are tripping out with just one or two "RV's" plugged in. Some of these monsters have, besides air conditioning, every appliance known to man - including hot tubs.

Internet sites are awash in clever ways to either bypass the OCPD, or to draw power from multiple circuits - or even to cobble a generator onto the PoCo feed. Codes? Safety? What do you want - it works, don't it?

Nor are park operators innocent. I just left a fur-ball where the park owner has been sneaking mobile homes into RV spaces.

As best I can tell, your typical park has an over-stressed service the day it opens.

#188596 - 08/19/09 10:00 PM Re: RV Park Calculations Art. 551 [Re: renosteinke]  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,103
There is a loophole in the HUD regs that allows you to call a sub-standard mobile home an RV just to get around stricter requirements. Some of that may be going on too.
I know because they tricked my son in law into buying one. We were just lucky that they never got hit by any kind of storm (fire or whatever)before they could dump it and buy a real house.

Greg Fretwell

#188604 - 08/20/09 12:29 AM Re: RV Park Calculations Art. 551 [Re: gfretwell]  
Joined: Mar 2004
Posts: 251
Kingwood, TX USA
Down here in the Gulf coast, From Galveston Tx and eastward, there are 100s of FEMA supplied trailers. They were supplied by FEMA after hurricane Rita and then IKE. Many of them are set up in the front yard of a damaged home. The electrical feeds span from a code approved connection (In the city of Galveston as an example) to wires stuck on a buss bar of a disconnect on the side of a flood (salt water) damaged home. Most were only supposed to be used for 4-6 mo. till the home could be rebuilt or repaired. Rita hit in 2005, Ike 2008, most are still here.

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