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14-50 extension cords okay?

Are actual RV extension cords safe to use with the mobile charger (14-50 adapter). Our outlet reaches but it is like 5 feet too short of where its ideally located which makes us do a few 3 car maneuvers to get it to work with all the cars. Was hoping to get a 25 foot 14-50 cable and use the slack to get the cables out of the way. Is this any safe? Will be plugging it in almost all the time.


Active Member
Supporting Member
Jul 29, 2018
'Safe' is a relative term, but yes, a 14-50 extension cord should be fine. Keep it as short as is reasonable.

The problem is that the adapters for the UMC have a temperature sensor in the plug, to try and detect when/if the outlet overheats. By moving that out to the end of an extension cord, it won't be able to measure the outlet temperature anymore.
If it gets warm enough to be questionable just make up your own extension cord upsizing the wire to the next bigger size. You want an "SO" type cord-- they come in many variants, if you have a choice an oil-resistant, cold weather flexible one might be best (SEOOW). I'd use locking connectors on it to ensure solid connections.


Well-Known Member
Oct 2, 2020
If an extension cord is left on the ground under certain conditions condensation can get into the plug connection. In some cases this will trip a GFCI. (You do have GFCI protection on the NEMA 14-50 charging circuit, right?)

Amazon sells extension cord covers, you might be able to find one that will fit the NEMA 14-50 extension cord, else figure out some way to keep the connection dry. You would have to modify the cover to accept the larger extension cord.
I have a fifth wheel with a 50 amp service. On occasion we've had to use an extension cable added to the regular 25 ft cable that came with the fifth wheel, in order to reach the campsite's service box, and we've never had an issue. Our trailer has two air conditioning units, microwave, coffee maker, etc. So we're pulling a lot of amps. We use a Progressive Industries 50 amp power protector for the trailer. What trips it is undervoltage conditions more than anything else. IMO you'll be fine with a good quality RV 50 amp cable.
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