Wire Sizing for 50a RV Outlet

[encantotom]

howdy all,

i am perplexed on how to size the wire for a 50a rv outlet. i know how to use wire size calculators and how it takes into account voltage drop etc. and i am familiar with how to wire them.

the perplexion is this.

I want to have full 50a at the rv if needed.

RV's are 4 wire with 2 hots, neutral and a ground and use a 240v outlet and plug. rv's are mostly all 120v pulling off of each leg. for example, i have 4 air conditioners. each are 120v and 2 are on each leg. when all 4 are on and blasting, they can draw almost 25a on each leg.

so.....if i am running 125' inside a building and using romex.....

do i use the wire size calculator for 120v 50a leg and size the wire for that

or size the wire using using 240v in the calculator

it makes a big difference in wire sizing. if i use the 240v it comes back as 3 # 6's and ground (6-3 romex)

if i use the 120v it comes back as #3 wire.

i talked to an electrician and he said 8/3.....

it is possible for me to run nearly 50a on a 120v leg at max.

any wisdom from the gurus here?

tom

 

[sberry]

This is a 4 wire feed to a panel in an RV. While its may be that all the loads are 120 some of it is opposite leg and balanced. If you tend to run the place wide open you need a 6 wire.

 

[Aceman]

6-3 Romex is rated for 55 amps. That is what I would run.

 

[Speedy Petey]

#8 is OK if conductors in conduit. If cable you must use #6. So 8/3NM is out of the question.

 

[encantotom]

Thanks. I talked to electrical PE this afternoon and he explained it all to me. 6/3 ROMEX will meet code.

Tom