Can I use any 50 amp extension cord?

Building a 50A RV extension cord can be a bit tricky, mostly because the "receptacle" part is not easy to find. The male "plug" is very common as all 50A motor homes have one. The PLUG is a NEMA N14-50P. The other end of the extension cord can terminate with a NEMA N14-50R or a NEMA N14-50C. The N14-50R you will find, such as at Home Depot, etc. are designed to be mounted in an electrical box of some sort. The best way to terminate the cord is to use the N14-50C, but that item is difficult to find, with your best bet being an electrical supply house. As you can see, the N14-50C can be connected directly onto the rubber cord without the use of a box and cover. Rubber cord would probably be 6/4 SEOOW, or similar.



NEMA N14-50P





NEMA N14-50R



NEMA N14-50C



6/4 SEOOW



Current price $4.39/ft

handy2sum wrote:
Is the 50amp receptical in the barn a 3-wire or a 4-wire with neutral? RV needs 4-wire.

It’s a 4 wire as we put it in when we got the RV.. In hindsight we should have put it a bit closer to the door.

valhalla360 wrote:
Make sure it's actually an RV receptacle. If not, it could damage your coach.

Also, how long will the cord be and what are you running? If you are just running the fridge, TV and a fan, likely not a problem. If you are trying to run 2 air/con units, hot water heater on electric and the microwave, voltage drop can be an issue if you are connecting up multiple extension cords to reach the outlet.

That was a question I had. But I do notice that the welder’s cords seem to have a 3 prong connection where my RV one is 4. Maybe that’s to keep morons like me from doing such things.

DrewE wrote:
If the cord does have the same connectors and wire size ("6/3", or 6 awg), it's equivalent to an "official" RV extension cord will work fine. There may be differences in the type of cable used (how resistant it is to abrasion or prolonged UV exposure, etc.) ...

The best quality cords would be labeled SOOW. (Big and heavy !). Second best woul be SJOOW. Anything else would be their, BUT that is not to say it is bad ! It won't be as flexible in cold weather and may not hold to being soaked in oil.

Do double check that you're getting the right connectors.

This is the MOST important thing !

Is the 50amp receptical in the barn a 3-wire or a 4-wire with neutral? RV needs 4-wire.

If it worked correctly on your RV without the extension and the extension has the same configuration, yes.

Hard to mess up 50A receptacle wiring....4 wires
2 hot, 1 neutral, 1 ground

30A is where it gets messed up
Dryer/welder.....3 wires 240VAC
2 hot, 1 neutral

30A RV...3 wires 120VAC
1 hot, 1 neutral, 1 ground


50A Cord/plug....
Ground is Round
Hots are blades/slots on each side
Neutral is blade/slot opposite the ground

As long as the shoe fits you are good to go. Should say NEMA 14-50 on the outlet.
Be cautious about using adapters or an owner installed system.

Make sure it's actually an RV receptacle. If not, it could damage your coach.

Also, how long will the cord be and what are you running? If you are just running the fridge, TV and a fan, likely not a problem. If you are trying to run 2 air/con units, hot water heater on electric and the microwave, voltage drop can be an issue if you are connecting up multiple extension cords to reach the outlet.

Please be sure it is a RV 50 amp service and not for a welder/dryer/etc which will probably fry your coach.