48windsor
Well-known member
Im thinking of running power from shop to a trailer about 100 ft away.
Has anyone done this ?
Advice
Has anyone done this ?
Advice
RV power run
- Thread starter 48windsor
- Start date
TurnipTruck
Well-known member
I’m not sure its possible for your question to be more vague.
nadogail
Well-known member
I once, in 1970, made a 12 Gauge extension cord that was the entire length of the SO Cable in the box. It was to power the radio equipment in a vehicle parked alongside a runway.
The alternative would have been to keep the engine running.
The alternative would have been to keep the engine running.
What are the power requirements of the trailer? 30A 120V, 50A 120/240V?
mike93lx
ALLIANCE MEMBER
Guess he could have omitted the 100ft piece, but that's about it...
@48windsor come on, add some detail. Is this a cord laying on the ground, trenching for buried wire, temporary, permanent, power requirements...?
rooster59
Well-known member
Need more info. Permanent wiring, RV weatherproof panel? Voltage, amperage? Assuming wire buried in conduit.
dave*99
Well-known member
Yes
PopcornSutton
Well-known member
If you don't want to run the A/C or microwave, a simple 120V 20 amp will keep things maintained.
My advice:
- I would use the right size breaker and wire for the amperage required in the RV.
- If you're not capable of doing the project correctly, then I recommend hiring a professional electrician.
- Don't skimp on projects, especially electrical projects.
- If a project is worth doing.... then it's worth doing correctly.
Steve from Socal
Well-known member
I would suggest making the run a 50 amp setup. The material cost is not much higher and it future proofs tha site.
mike93lx
ALLIANCE MEMBER
Any chance 240v would be helpful there? If so, and you actually need 30a, I'd probably run 4x #8 copper xhhw or thwn in 1" conduit. Should be able to do a #10 egc instead of an 8,though.
If you don't really need to pull 30a, and will never need 240v, I'd do 3x #10 copper xhhw or thwn, also 1" conduit, but 3/4 could work if it's a straight shot
I'd also put in at least one, but probably two ground rods
wyliesdiesels
Well-known member
And #8 THWN would allow for 50a circuit
mike93lx
ALLIANCE MEMBER
Yeah. I was mainly thinking of voltage drop. If it really is 100ft, then up sizing may not be worth it
dcg9381
Well-known member
All day long.. It's really not any different than installing any other power drop. Use the right breaker, and wire for the length of the run.
Is this a 30A @ 120V or 50A @240V RV?
My "cheat" is to install a dual-pole (240V) 30A circuit, 30A breaker. "50A" RVs are really only 120V - they don't use both hots... You'll be able to run them just fine on 30A 240V circuits and 14-50Rs.
As I read the voltage drop tables, if you use copper, you'll need 6-8AWG wire for 100 feet though at 30A. If @wyliesdiesels says you can get away with #8 THWN at 50A, that seems to be the way to go as you'll need similar wire for a 30A circuit.
75gmck25
Well-known member
I would guess the one in your picture is quite expensive. Something like this might be less expensive, and would still be very flexible.
dcg9381
Well-known member
I use the Siemens Talon all over the place. Used to be able to buy this for $150-$175. Inflation I guess. It has more slots than the GE panel.
reader2580
Well-known member
Are you basing this on the 75c rating? Every time I've seen wiring for 50 amp RVs it is 6 AWG. I had a bunch of leftover 8 AWG so I used a 40 amp breaker on my RV circuit. I've never tripped the breaker since RVs rarely pull a full 50 amps.
mike93lx
ALLIANCE MEMBER
6 if it is nm-b because that is at 60 degree. Thwn in conduit is fine for 75 degrees
reader2580
Well-known member
I used 8 thhn/thwn in conduit and used a 40 amp breaker because everything I saw was 6 AWG to do 50 amps for an RV.
mike93lx
ALLIANCE MEMBER
They must have been for nm-b cable. You are fine for a 50a breaker
wyliesdiesels
Well-known member
VD @ full 50a load (which wont happen with an RV) would be 2.9%... will be fine
wyliesdiesels
Well-known member
yes because the terminations are almost always 75°c rated. I havent seen a 60°c rated terminal in years
wyliesdiesels
Well-known member
most likely because they had no clue how to read 310.15(b)(16) or it was a very long run. my money is on the latter
wyliesdiesels
Well-known member
doubt it since nm-b cant be used outdoors or underground
mike93lx
ALLIANCE MEMBER
Not all RV receptacles are outdoors, though
Innovate1
Well-known member
I think your statements could confuse people not familiar with RV wiring. 50A RVs certainly do use both hots, they just typically don't have any 240V equipment except in VERY high end rigs. 50A RV feed is both legs with 240V between them. Doesn't change the wiring to the RV receptacle from what would be a typical 240V drop. If you can run a 50A RV on 30A circuit with both legs depends on the RV and what all you want to run at the same time. With a little attention to what all is running at the same time it would be ok.
If you are going to run #8 copper for the 30A 240V circuit (due to voltage drop when using only one leg) why not put in a 50A breaker and have a standard RV 50A drop? Your "cheat" doesn't even save any money on the cost of the breaker.
Steve from Socal
Well-known member
This is correct with this exception, to do the 50 amp service you need a neutral along with the two hot legs. The 50 amp circuit is a 4 wire while the 30 amp is a three wire.
dcg9381
Well-known member
Agreed. And I've seen electricians wire RV outlets wrong.
Putting it simply, you can use a 3 wire (hot, hot, neutral, ground) connection to a 14-50R at 240V@30A and it will power up what the RV people call "50A RVs".
As long as the RV has no more than 2 air conditioners, it should run just fine on 30A @ 240. A full 50A @240V RV circuit will pull 4 ACs.. But we're talking "Willie Nelson" bus size here...
@wyliesdiesels I trust more than the voltage drop calculators. If he says you can use #8 copper, then I buy that. I use #6 copper. When I did the 100 foot calculation, it looked like you had to up-size the wire.
My "cheat" is for shorter runs, you can get away with 10ga wire for 240V@30A. It's way cheaper (wire cost) and easier than running 6ga copper and doing 50A.
Last edited:
reader2580
Well-known member
I would suggest always wiring up a 50 amp RV receptacle as 240 volt. The L14-50 receptacle could end being used for something other than a RV that expects 240 volt.
wyliesdiesels
Well-known member
i did the calcs myself using the formula i posted in the FAQ sticky. i dont bother with online calculators because they can have so many "behind the scenes" variables programmed into them its hard to know what formula theyre using.