BAHTAH
Senior Member
- Location
- United States
It?s been twenty years since my last RV Park installation so I thought I would post this for some confirmation or criticism on my method of calculation. A friend asked me to do some calculations for his new RV Park and this is what I have done: He wants 35 spaces total and exceeds all the minimum requirements for size of pedestals since he wants 14 at 50amps and the balance at 30amp. So 14 pedestals with be 20/30/50 and the remainder will be 20/30. I have used demand factors no less than 80% since it seems RV?s in general continue to come equipped with more goodies every year and there will be road-way lighting load to be added. Because of the distance of the feeder runs, most feeders only have 4 pedestals. I will give one feeder example: Four 30amp pedestals calculated at 100% demand. The distances from the feeder breaker to the pedestals is: ped-1 (220?), ped-2(280?), ped-3(340?), ped-4(400?). I figured the sum of the ampere/ft and load amps for the pedestals and then divided the sum of the ampere/ft by the sum of the amp load to get the load-center-length. 33000af/120a=275?LCL. Then I figured the feeder amps (not the same as the LCL amps) based on 3600VA for each pedestal and two pedestals on each phase of the 120/240V feeder. 7200VA per phase=14400/240=60amps. Then I did a voltage drop calculation using the Load-Center-Length, keeping the voltage drop below 3% (5% is allowed) using #1/0 AL. My voltage drop calculation came out at 7 volts or 2.76%. The end result would be a 100/2 breaker feeding (3)#1/0 XHHW-AL & #4 Copper ground in 2? PVC-Sch-40. I have not been to the site in awhile, managed to get injured and end up in the hospital, its been over a year of recovery, this getting old is not all it's cracked up to be. Any comments would be appreciated. Thanks!