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Discussion Starter · #1 ·
looking at wiring 16 50 amp rv sites. According to my calcs its 376 amps. Im looking to use a 400 amp loadcenter with 50 amp breaker to each site. See anything im missing, thx
 

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looking at wiring 16 50 amp rv sites. According to my calcs its 376 amps. Im looking to use a 400 amp loadcenter with 50 amp breaker to each site. See anything im missing, thx
How are you getting that low of a number?
 

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I'm not looking at the code book but I think art551. What do you come up with ?
I'm not looking at the code book but I think art551. What do you come up with ?
16 * 50 = 800 * % allowed by NEC.

376/800 = 47%. I'm pretty sure that using the 16 outlet count is more than 47%. My code book is packed away.
 

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On a hot night, at full capacity, I'd assume that 16 fifth-wheels with both their air conditioners running would exceed that number.
 

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Discussion Starter · #6 ·
47% is the demand factor for 16-19. But that is some of my concern also. But its already been bumped up from previous code of 9600 va to 12000 va per site. I'm with you on that but I would think the code engineers would have already thought about that ?
 

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47% is the demand factor for 16-19.
I figured it would be higher than that, I would have bet (and lost) money on that.

So, based on what you've said, code says you are good to go but ... that is the minimum and I think you should try to upsell the customer, but a 400-amp service may hold up just fine.

But more important would be voltage drop considerations.
 

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Years ago before the nec2017 adaptation, 2014NEC... 6, 50amp sites would suffice a 200amp service at 240volt. After 6 the load calc was generous at allowing up to 10 on a 200service.
Last year I upgraded a 200a to 400/ 320 with 12 sites mixed with 50s and 30s. BUT! during the 4th of July I read 210 amps on A phase and only 80 on B.. its so hard to balance with some campers having 30 and some with 50 with 3 RTUs. Good luck, but the allowable ampacity used to drop all the way to 25% after 12 camp sites
 

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I have seen RV's that only had the A/C on 240 volts and all 120 volt loads on 1 phase. Always thought the 30 amp ones should also be 120/240 volts. So many times the 30 amp ones also have an extension cord plugged into a 15 amp receptacle for such as a microwave.
 

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Discussion Starter · #12 ·
Yeah I'll figure something out. It's hard to wire for "what ifs". Thx everyone for all the input
 

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I'd personally look at putting those 20/30/50 panels at each site, then you got all your bases covered. But those get fed with a 100amp so not sure that would effect your load calculation. I just put one in for a guy in a garage so he has a spot for his rv and fish house.
 

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Most of the power pedestals I've wired (for marinas) would have the 120V receptacles wired off of A phase. So if you have all of your 30A receptacles all on A phase you will have a hard time balancing the loads. IF you are using power pedestals you might want to wire black to A phase on 1/2 of them and wire black to B phase on the other 1/2.
 

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Note: when using a 20/30/50 panel, you do not need to be overly concerned with feeding the pedistal with more than 50 amps because if a 50 amp trailer is using it, they are unlikely to need any other power.
 
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