Rv outlet, how long before derating

[signcrafter]

Going to be adding a 30 amp 110 RV outlet either on the outside or inside of the garage for our travel trailer. This will be about 60 to 65 feet from the sub panel in the garage by the time I go up and over and back down. Is 10-2 romex good enough or do I need to derate for that distance? I have lots of 10-2 romex so hoping that will work and wont have to buy 8-2 since I'm guessing that will add up fast. But also want to do it right. Thanks

 

[pattenp]

You're fine with #10 romex.

 

[Shiftless]

I calculated a bit more than 3% voltage drop if your RV is drawing your full 30 amps. (125 volts) Most of the time I suppose you will be using a fraction of that amount. You’ll be fine.

 

[nadogail]

There is ample copper in 10 AWG, for your load at that length.

 

[wyliesdiesels]

Should be fine with the #10

 

[dcg9381]

Suggestion:

I dunno your full use case, but these days I run 10/3 to a 14-50R (Standard 50A RV outlet) on a 30A breaker. I put a label of "30A @240V" on the plate. This gives you twice as much available power if you're ever landing 50A RVs at your place or need to run a welder. 50A RVs really don't need 50A unless they are 3 or 4 AC "monster class" RVs.

You use the standard 50A to 30A adapter that I'm sure you already have to plug in your RV.

 

[signcrafter]

Suggestion:

I dunno your full use case, but these days I run 10/3 to a 14-50R (Standard 50A RV outlet) on a 30A breaker. I put a label of "30A @240V" on the plate. This gives you twice as much available power if you're ever landing 50A RVs at your place or need to run a welder. 50A RVs really don't need 50A unless they are 3 or 4 AC "monster class" RVs.

You use the standard 50A to 30A adapter that I'm sure you already have to plug in your RV.

I kind of like this idea. I would like a 50 amp outlet in case friends stay over with there camper. But is this code compliant?

 

[dcg9381]

I kind of like this idea. I would like a 50 amp outlet in case friends stay over with there camper. But is this code compliant?

I'll let someone else answer that. I don't know of any prohibition for using a 50A receptacle on a 30A circuit with an appropriate breaker. I've seen some comments that the outlet itself is (perhaps) misleading, which is why I put a label on it. I "believe" this is allowed with a single breaker / single outlet scenario. The sparkies will know better than me. I believe it's covered under NEC 210.21(B)(1) - it's allowed as it's a non-branch circuit, so you can't overload it without tripping the breaker.

 

[Bert_]

Suggestion:

I dunno your full use case, but these days I run 10/3 to a 14-50R (Standard 50A RV outlet) on a 30A breaker. I put a label of "30A @240V" on the plate. This gives you twice as much available power if you're ever landing 50A RVs at your place or need to run a welder. 50A RVs really don't need 50A unless they are 3 or 4 AC "monster class" RVs.

You use the standard 50A to 30A adapter that I'm sure you already have to plug in your RV.

It technically a code violation but it's really a good option and I have done exactly that before.

If someone wants to argue a safety concern I would ask how it's different than plugging a 50A adapter into a standard 30A RV outlet

 

[Norcal]

It technically a code violation but it's really a good option and I have done exactly that before.

If someone wants to argue a safety concern I would ask how it's different than plugging a 50A adapter into a standard 30A RV outlet

It's not "technically" a code violation, is flat out a code violation, a 50A receptacle is only permitted to have 40A or 50A overcurrent protection, but the worst that can happen is the breaker trips, which in the annoyance category. The problem is the 50A to 30A adapters, and 30A to 20A adapters, none of them are listed for good reason.

 

[dcg9381]

It technically a code violation but it's really a good option and I have done exactly that before.

Can you guys cite code on where it's a violation? It has to be expressly prohibited. NEC 210.21(B)(1) is a branch circuit deal. If it's not prohibited, it's allowed.

If someone wants to argue a safety concern I would ask how it's different than plugging a 50A adapter into a standard 30A RV outlet

I'd claim the danger is the opposite, using a 50A adapter on a 50A protected 14-50R to go down to a 30A RV outlet, which is pretty common in the RV space. You'd smoke wires before tripping a breaker.

 

[Bert_]

It's not "technically" a code violation, is flat out a code violation, a 50A receptacle is only permitted to have 40A or 50A overcurrent protection, but the worst that can happen is the breaker trips, which in the annoyance category. The problem is the 50A to 30A adapters, and 30A to 20A adapters, none of them are listed for good reason.

Yes the code says 40 can use a 50A receptacle. Why is a 40A circuit OK but a 30 is not? If there is a safety issue why not require 40A receptacles? No doubt the industry could make one.

I use the word technically to mean it is a code violation but not a safety issue. The original intent of the code is to cover safety not design issues.

 

[wyliesdiesels]

Yeah i dont see a safety issue with that. Wonder what the CMPs reasoning behind that code was...

 

[Stuff]

It's not "technically" a code violation, is flat out a code violation, a 50A receptacle is only permitted to have 40A or 50A overcurrent protection, but the worst that can happen is the breaker trips, which in the annoyance category. The problem is the 50A to 30A adapters, and 30A to 20A adapters, none of them are listed for good reason.

Which code section do you see that in? NEC states "A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit." The verbiage about 40 and 50 amp circuits and the receptacle table is for multiple-outlet branch circuits.

 

[Bert_]

I checked my codebook and what I thought would not allow this installation, 210.21(B)(3), applies to circuits with (2) or more receptacles. A circuit with a single receptacle would not apply. I can't find anything else on the subject.

Unless someone else has something I am going to say a single 50A receptacle on a 30A circuit is code compliant

I have done this exact install before and assumed it did not meet code, but apparently it was fine all along!

It's not "technically" a code violation, is flat out a code violation, a 50A receptacle is only permitted to have 40A or 50A overcurrent protection, but the worst that can happen is the breaker trips, which in the annoyance category. The problem is the 50A to 30A adapters, and 30A to 20A adapters, none of them are listed for good reason.

 

[theoldwizard1]

Suggestion:

I dunno your full use case, but these days I run 10/3 to a 14-50R (Standard 50A RV outlet) on a 30A breaker. I put a label of "30A @240V" on the plate.

I agree ! About 40¢/ft difference.

 

[dcg9381]

I agree ! About 40¢/ft difference.

Around here 6/3 is almost 2x per foot over 10/3.

 

[Norcal]

Which code section do you see that in? NEC states "A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit." The verbiage about 40 and 50 amp circuits and the receptacle table is for multiple-outlet branch circuits.

See table 210.21(B)(3). But as I wrote the worst that can happen is a tripped breaker, not like putting a 15A on a 50A circuit which is bad.

 

[Stuff]

See table 210.21(B)(3). But as I wrote the worst that can happen is a tripped breaker, not like putting a 15A on a 50A circuit which is bad.

That table is only used for 210.21(B)(3) - "Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3)"

The 2023 NEC clarified this by updating the table's title.

 

[Bert_]

See table 210.21(B)(3). But as I wrote the worst that can happen is a tripped breaker, not like putting a 15A on a 50A circuit which is bad.

I thought that at first too. The table is for (2) or more receptacles.

 

[dcg9381]

I thought that at first too. The table is for (2) or more receptacles.

Again, I argue, "where is this prohibited"?

In the context of NEC, if it's not prohibited, it's allowed.

I'm not arguing that it's "smart" but a 50A rated receptacle on a 30A breaker is at worst going to be "confusing" (despite my 30A label on it) but it's not unsafe or unreasonable.

The number of worn out RV plugs I've seen astounds me. There are so many RV parks running under voltage or just that have worn out plugs.. I'd rather run 50A rated plugs and pull 1/4 of their rated output, seems "not dumb" to me.

 

[Bert_]

Again, I argue, "where is this prohibited"?

In the context of NEC, if it's not prohibited, it's allowed.

Why argue when I agreed with you in multiple posts?

 

[dcg9381]

Why argue when I agreed with you in multiple posts?

Apologies, not speaking to you directly. Speaking to those that say it's a "violation". Requesting citation of violation (politely) - just like I'd do with any local code inspector who is dead *** wrong.

 

[Norcal]

I thought that at first too. The table is for (2) or more receptacles

Might be right, I would not lose sleep over it.

 

[FredWanaker]

here any electrical cable to a trailer in a yard or at the street is the code violation. You can run one to charge the battery but it can't be an overnight thing.

 

[signcrafter]

here any electrical cable to a trailer in a yard or at the street is the code violation. You can run one to charge the battery but it can't be an overnight thing.

HOA rules? I could see some codes to keep people from living in campers. But I use mine for when cleaning it before and after a trip. A lot of times its 80 to 90 degrees so being in it without AC on is cruel. Also will turn the fridge on to get it cooled down since it takes a while to get it to temp after being off. We do get guests every so often that will stay in there for 2 to 3 nights also.