Tuesday, September 26, 2023


RV Electricity – Just Ask Mike (J.A.M.): Dogbone adapter confusion cleared up – Part 1

By Mike Sokol

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM.

Dear Readers,

I’ve had several postings this week over on my RVelectricity Facebook group about dogbone adapters. No, these are not the bones that you actually feed your dog. But you’ll see below that they sort of resemble the cartoon version of a big juicy bone any cartoon dog would love.

In the RV world these are AC power adapters that allow you to plug your 50-amp shore power RV into a 30- or 15-amp pedestal outlet. Or you can go the other way ’round and plug your 30-amp shore power RV into a 50-amp pedestal outlet.

Power to the people…

But I’ve noticed some confusion in the naming of these adapters. For example, about half of my readers would call this male 30-amp to female 50-amp adapter a 30- to 50-amp dogbone since it allows you to use a 30-amp pedestal to power a 50-amp RV. However, the other half of you will call it a 50- to 30-amp dogbone adapter since it allows you to plug a 50-amp RV into a 30-amp pedestal.

This isn’t just some argument about semantics and double spacing after the period at the end of a sentence. (Yes, our editor, Diane, and I discuss this all the time, and I throw in the occasional double space just to see if she’s paying attention. [He does, and then uses that as his excuse. 🙄 —Diane])

Who’s on first?

For example, take a look at this next dogbone adapter, which is the reverse of the previous one shown. Note that it’s a male 50-amp to female 30-amp adapter. So do we call this one a 50- to 30-amp dogbone because it lets you use a 50-amp outlet to power a 30-amp RV? Or do we call it a 30- to 50-amp dogbone since it lets you plug your 30-amp RV into a 50-amp outlet?

TNSTAAFL (There’s No Such Thing As A Free Lunch)

Now in neither of these cases do these dogbone adapters actually give your RV more amperage. That’s determined by both the circuit breaker capacity of the pedestal outlet, and well as the circuit breaker capacity of the RV’s load center. So a 30-amp RV plugged into a 50-amp outlet is limited to 30 amperes of current (or at least it should be) by its own inlet breaker. And a 50-amp RV plugged into a 30-amp pedestal with an adapter can only use 30 amperes of current because it’s limited by the pedestal’s outlet circuit breaker.

Let’s take a poll

This is so interesting (and confusing) that I’m going to take a poll to see what you call the dogbone pictured below. I’ll give you the results of the poll next week along with how I would name it. So please take this poll (seriously) as I’m trying to determine the best way to write about this simple (yet confusing) adapter.

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
Join Mike’s popular and informative Facebook group.
And you don’t want to miss Mike’s webcasts on his YouTube channel.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign



  1. Personally what circuit you plug into determines what you call it. If you plug into a 30A circuit it is a 30A to (whaterver) adaptor. The plug and breaker on that plug determine the circuit type and then the female end determines what it goes to.

    Just how I do it.

  2. I don’t refer to them as a “dog bone”, I use the term “step down” or “step up”, helps increase the understanding.

  3. I have a 50A to 15A dogbone which I use to keep batteries charged when rig is in storage. Lately I have noticed that if I turn on my DC switch inside the rig my Hughes surge protector trips with an E6 error code that means ground and neutral reversed. This only happens when rig DC switch is turned on. With it off I get no errors and I have AC flowing fine in rig. Any ideas?

  4. Gee, you forgot those of us who have a twist on 50-amp. But we, too, have to use an adapter when at a park with only 30 amp service. The other question therefore: do you use the adapter at the rv or at the post? We use it at the rv to avoid having to lift that 50 amp cable out.

    • I’ll cover twist-lock connections at a later date. And generally it’s okay to either use the adapter at the post so you can utilize your existing shore power cable, or carry an extra 30-amp shore power cord and place the adapter closer to your RV. However, using your 50-amp shore power cord for a long run to the pedestal can reduce the voltage drop in your shore power cable by 40% compared to a 30-amp shore power cord.

  5. Is it just my conservative thinking? I just don’t think it’s a good practice to be able to plug a 30 amp rated cord into a 50 amp receptacle protected by a 50 amp breaker. That goes against all electrical best practices. Hopefully the main breaker in the unit will trip before burning up the cord. All too many times I have seen breakers fail.

    • Yes, that’s correct. And it certainly is a code violation on paper. However, every RV adapter manufacturer sells that type of product, and the inspectors seem to look the other way.

    • I’ve started using a 50 to 30 plug almost every time I hook up now. It seems most people, at least in the past, have a 30 amp hookup and the receptacles reflect that heavy use. The 50 amp receptacle is less used and, I think, provides a better connection in most cases. I don’t try to use more stuff than I do when hooked to a 30 amp receptacle so I don’t see the harm. But, I could be wrong . . .

  6. I rather imagine that what you call it depends on what amperage your RV actually uses. As a diesel motorhome 50 amp’r I would call it 50 amp to 30 amp since that’s how I’d use it. On the other hand (note 2 spaces after the period) if I had a 30 amp trailer I would probably call it 30 amp to 50 amp since that’s what I would then be trying to do. Doesn’t help the discussion but it works for me.

    • 😆 I think extra spaces after periods are automatically removed in this commenting program. But thanks for thinking of me. 😉 —Diane at RVtravel.com

        • Good morning, Bobby. Mike just likes to give me a hard time about my being so persnickety about typos, etc. The spaces are when you hit the space bar after a word or a period. When I learned to type back in the Dark Ages (60+ years ago), two spaces were required after a period (between sentences). And as a legal secretary/paralegal since 1966, I put millions of double spaces between sentences over the years — until I started working for Chuck in 2013. In journalism there is only one space after a period — so it took me quite awhile to reprogram my brain (and my right thumb!) to just put in one space between sentences. (Chuck got a kick out of catching two spaces between sentences. 😆 ) What a long story about a little space! Sorry. Have a great day, and stay healthy. 🙂 —Diane at RVtravel.com

          • 😆 Yeah, I heard about that. But in my case, when I was trying to restrict my brain/thumb to one space between sentences, it was more like “Chuck has spoken” — because he would certainly let me know if there was an extra space. BTW — My long-time attorney boss (of 45 years) was a friend of Bill Gates’ father, and his sons went to school with Bill. And an investment group my boss was in had briefly considered investing in Microsoft at the very beginning. They decided not to invest because “it wasn’t going to amount to anything.” If any of those investment club members are still alive, they’re probably still kicking themselves. 😯 —Diane at RVtravel.com

  7. All these silly names. Being in the marine business for years…never heard any adapter cable called a “dog-bone”. It’s either a 50 to 30amp adapter or a 30 to 50 amp adapter. Crazy

    • Don’t shoot the piano player, he’s doing the best he can. 🎹 Yes, I never heard of a dogbone adapter either until I started writing for the RV industry 10 years ago. So I only report what my readers ask me.

  8. Many older campgrounds in the USA and especially in Canada and Alaska, only have 30 Amp service at best. In our many travels we have even been in Fairgrounds that only had 120 V 20 Amp service. Our first Class A had a 30 Amp power cord, so we had dogbones that went from 50 Amp service to 30 Amp and also 125 Volt 20 Amp service to our 30 Amp cord.

    Our 2nd and now on our third Class A both are 50 Amp coaches. So we carry dogbones that go from a 30 Amp service to our 50 Amp cord and also a 120 Volt 20 Amp service dogbone that plugs into our 30 Amp dogbone that plugs into our 50 Amp cord.

    I suggest everyone carry all varieties of proper dogbones that will provide your RV with the lowest 120 Volt 20 Amp to the highest 50 Amp service. You never know when you will need them. Be prepared and you won’t regret it.

    Oh, the dogbone in the poll is a 30 Amp to a 50 Amp power cord.

    Stay well, Stay safe.

    • Sorry Dick and Sandy, as an Alaskan for the last 52 years, I can tell you that it is true that most of the older, smaller RV parks have only 30 amp, we have many parks that also have 50 amp pedestals.

  9. Trick question and answer. I’d call it 30 to 50, but no way are you going to get the 50 amps in your RV out of 30 amp plug at the pedestal. The 2nd response is correct in name only, not in practicality. The first response is correct in application, but the wrong nomenclature “name”.

  10. I’ve always called out adapters by going from what you have to what you need. Like socket wrenches. You have 1/2” drive, need 3/8. So it’s 1/2 to 3/8.
    Or, you have a 15 amp ext cord, need to adapt to 30. I would call it a 15 to 30


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sign up for the

RVtravel Newsletter

Sign up and receive 3 FREE RV Checklists: Set-Up, Take-Down and Packing List.