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Wot size wire for buried cable to 50A RV receptacle at home?

joebedford
Nomad II
Nomad II
I'm planning on putting a sub panel in my shop on the side of the house where my RV is stored during the summer. Not worried about the gauge of wire from the main panel to the sub panel - a problem for another day.

I'd like to bury a power cable and install a 50A receptacle right next to the RV. It's going to be about 60 cable-feet from the subpanel to the receptacle on the post.

My hot tub is 60A and the electrician installed and the inspector approved 6 gauge wire for a similar length run.

Is 8 gauge allowed or should I be burying 6 gauge?

I'm planning on burying it in 1-1/2" PVC.
16 REPLIES 16

aruba5er
Explorer
Explorer
NEC (code) requires that the conduit run be complete before pulling wire. And no more than 4 90 degree bend or equalvent. and too many do it yourselfer's use plumbing fittings rather than electrical fittings. Yes, they put wire in drain or vent elbows. And btw pipe is in 10 ft lengths. not 8 ft.

westend
Explorer
Explorer
Hey myredracer,
Are you in the trades?

I know about Mex, he's just an old genius down there at his bungalow that's had more electrons spin through his hands than most of us combined.:B
'03 F-250 4x4 CC
'71 Starcraft Wanderstar -- The Cowboy/Hilton

Empty_Nest__Soo
Explorer
Explorer
kaydeejay wrote:
NEC code says #8 wire is good for 40A, so that is what I have with a 2-pole 40 amp breaker for plugging in at home. . .


+1

I figured that was more than enough for anything I'm likely to want to power up at home.

Wayne
Wayne & Michelle

1997 Safari Sahara 3540

MEXICOWANDERER
Explorer
Explorer
Make your own Chinese fingers. Use SPECTRA twine. Start a foot from the end and work toward the end. One loose wrap, Tuck under then another wrap a half-inch further toward the end. Keep tucking the long lead under as you wrap over and over again. Spectra is incredible. Twine can be attached to a bumper of a car and 800 lbs of force applied without breaking it. Available at Marine chandlers. I pulled eight triples of 10/2 wire through 1-3/4" ABS over 300' (100 meters) when I was running the RV park electrical down here. The Spectra didn't even yawn.

myredracer
Explorer II
Explorer II
For 50 amp service, you could also use larger gauge aluminum, #4 (needs to be terminated properly and conduit size may need to be increased). #6 Al *might* possibly work but check NEC table 310.16. Alum. can be much cheaper than copper.

The conduit at 1 1/2" size appears to be overkill. It looks like according to the NEC, you can get 3 #6 + ground in a 1" conduit (with copper wires). 1" conduit would simplify the work and be cheaper.

As mentioned, perhaps 50 amps is unnecessary and 2p-30 amps will be just fine which would save $$ and make the install much easier. You could still size the conduit for 50 amps in case you decide you want 50 amps in the future.

I highly recommend installing a disconnect switch at the RV receptacle so you aren't plugging the shore power cord in live which will eventually damage the blades on the plug. Should be rated heavy duty or a circuit breaker.

wnjj wrote:


I ran 3 strands of 1-o plus a smaller ground through 100' of 2" for my shop. Tied a string to a plastic grocery bag, shop vac'd it through, then tied a rope to that then finally the wire.


This is an easy method for the average person as long as you have a shop vac. Depending on length and number of bends, a fish tape can work (cheap at Harbor Freight). Pulling wire and gluing the pipe one length at a time is not the normal way of doing it but would work if careful.

To pull the wire, a wire sock works the best and will not let go - these don't cost much. Bending the wire over at the end or taping the pull cord to the wire bundle can be too fat inside the conduit and make it hard to pull. Ordinary liquid dishwashing soap can be used as a lube if needed.

wnjj
Explorer II
Explorer II
lanerd wrote:
I ran #6 copper through 1-1/2" pvc, 24" deep trench for about 100'. My inspector passed that with flying colors. I ran the wire through each 8' section of pvc and then once all wire was through the pvc, I then glued the pvc ends together one at a time in the trench. Trying to run #6 wire through a already glued pvc would be really, really difficult.

You had better contact your inspector to make absolutely sure on the #8 wire.
Ron


I'd much prefer to glue first, then pull. If you glue with wire there you may have glued the wire to the pipe and cannot easily pull it out if at all. If it's too tough to pull, use a larger size of pipe and/or use lube.

I ran 3 strands of 1-o plus a smaller ground through 100' of 2" for my shop. Tied a string to a plastic grocery bag, shop vac'd it through, then tied a rope to that then finally the wire.

kaydeejay
Explorer
Explorer
joebedford wrote:
Big Katuna wrote:
You will never use anywhere near 50A on each leg. Rarely over 25 per leg unless you run microwave, hair dryer and an electric heater.

You could use dual 30 breakers and drop the wire size to 8. You could still run both ACs microwave and fridge.
I hadn't thought of that. Given that it's rarely used in that location 30A per leg would be plenty.
NEC code says #8 wire is good for 40A, so that is what I have with a 2-pole 40 amp breaker for plugging in at home.
Local inspector signed off on it.
Keith J.
Sold the fiver and looking for a DP, but not in any hurry right now.

joebedford
Nomad II
Nomad II
Big Katuna wrote:
You will never use anywhere near 50A on each leg. Rarely over 25 per leg unless you run microwave, hair dryer and an electric heater.

You could use dual 30 breakers and drop the wire size to 8. You could still run both ACs microwave and fridge.
I hadn't thought of that. Given that it's rarely used in that location 30A per leg would be plenty.

joebedford
Nomad II
Nomad II
smkettner wrote:
Are you running from the hot tub sub-panel? Because it may not have a neutral and you must have all 4 wires.
No - there's no subpanel for the hottub - just a 60A breaker in the main panel then #6 through a service switch to the tub. 4 wires with neutral. It's at the other end of the house.

Empty_Nest__Soo
Explorer
Explorer
Dannyabear1 wrote:
3- #6 & 1- #8

For a 60' run @ 50 amps: 3- #6 copper, for the 2 hot legs and neutral. If aluminum, #4.

#8 will work for ground, although I think #10 copper ground will meet the current code requirements.

Wayne
Wayne & Michelle

1997 Safari Sahara 3540

MEXICOWANDERER
Explorer
Explorer
Your hot tub is not as voltage sensitive as your R.V.

Code violation may be costly. Say you experience a damaging electrical event and your insurance is set to foot the bill. All they need to do is send someone to verify the loss....

Electrical codes exist for your protection.

Dannyabear1
Explorer
Explorer
3- #6 & 1- #8

Big_Katuna
Explorer II
Explorer II
You will never use anywhere near 50A on each leg. Rarely over 25 per leg unless you run microwave, hair dryer and an electric heater.

You could use dual 30 breakers and drop the wire size to 8. You could still run both ACs microwave and fridge.
My Kharma ran over my Dogma.

time2roll
Nomad
Nomad
#8 is good for maybe 10' max. You need #6.

May need to oversize the conduit if using a bundled cable.

Are you running from the hot tub sub-panel? Because it may not have a neutral and you must have all 4 wires.