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Topic Closed50amp to 30 amp dog bone

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Shane View Drop Down
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Direct Link To This Post Topic: 50amp to 30 amp dog bone
    Posted: 30 Jan 2020 at 3:01pm
I made reservations at a site for this July 4th and all they had was a 50 amp available. I did buy a 50 amp to 30 amp dog bone. My question is are they SAFE to use. I am using a plug protector on my pod. I have yet to use it so this will be my first time using the dog bone.
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Direct Link To This Post Posted: 30 Jan 2020 at 3:59pm
Lot of discussion on this topic. They have been in use for years, I own one and have used it on occasion. Having said that - there is an opportunity for issues - the issue occurs IF there is a fault in the power line that exceeds 30 Amps but is less than the near 50 Amps to kick the 50Amp CB in the power stantion. I have yet to see the issue reported, but it could. That's been the discussion. Personally I will continue to use my dogbone when required. IMHO.
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Direct Link To This Post Posted: 30 Jan 2020 at 4:02pm
There is a debate on this question, on this forum and elsewhere. 

Here are the facts, so you can make your own decision.

The 50A circuit at the campground has a circuit breaker on the pedestal that will trip at 50 amps. The trailer panel has a circuit breaker on it that will trip at 30 amps which will protect everything downstream of that. In between the dog bone and the breaker in the trailer panel is your cable with a connector on each end, a receptacle on the trailer, and wiring between that receptacle and the circuit breaker in the trailer, all of which is rated to handle 30A but not 50A. 

So, if you get a short in between the dog bone and the trailer circuit breaker that allows more than 30A to flow but less than 50A you can overheat the cable, connectors, receptacle, or wiring which could cause a fire. If the short is more than 50A the circuit breaker on the pedestal will trip. 

Because of this potential risk there is a label next to the trailer receptacle which says not to connect it to a circuit that can provide more than 30A. The plug protector you have protects from some other things but not from this particular risk. And the dog bone manufacturer is not responsible if there is a problem, they meet the requirements they need to meet to sell their product. its up to you how you use it. 

Is such a short circuit (less than 50A but greater than 30A) possible? Yes, I have seen similar shorts on other circuits but not on RV's. Is it common? Not at all, very uncommon on RV's if its happened at all. 

So, there you have it, up to you to decide what you're comfortable with based on your risk tolerance. 




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Direct Link To This Post Posted: 30 Jan 2020 at 4:16pm
I've been looking for an in-line circuit breaker or fuse setup that could be plugged in to the electrical line between the pedestal and RV receptacle to no avail.  I'm a bit befuddled that someone doesn't make one.

Edit:  Maybe this??

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Direct Link To This Post Posted: 30 Jan 2020 at 4:35pm
I would guess that no it doesn't monitor for current as it only says it protects from voltage spikes or surges. 
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Direct Link To This Post Posted: 30 Jan 2020 at 4:48pm
So I continue to be somewhat confused by the 50-to-30 dogbone thing.  I found this:

The option to run a 30-amp recreational vehicle, or RV, from a 50 amp outlet is useful to many RVers. To avoid catastrophic damage to appliances, equipment and wiring circuits, and a real danger of fire, the amperage must be stepped down to 30 amps. This is easily done, by using a 50-male to 30-female connector, referred to by RVers and manufacturers as a "dogbone" connector, because it has two bulbous terminals joined by a short, slender cord. Dogbone adapters comprise a heavy-duty three-conductor wire between a 50-amp plug and a 30-amp outlet. They work by leaving one of the 50 amp outlet's two positive 120-volt legs unconnected to the 30-amp outlet.


So if this is correct and the dogbone actually steps the current down to 30 Amps right out of the pedestal, is there really any danger?


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Direct Link To This Post Posted: 30 Jan 2020 at 5:40pm
I disagree with the step down remark. Each leg of a 50 Amp service has 50 Amps available. So the connection from a 50 Amp service to 30 Amp service, eliminates one leg of the electricity from the 50 Amp service. So you have a 50 Amp availability coming into a 30 Amp service. Again, I have not seen one instance of an issue with this hook up or the use of a dogbone. BUT - electrically it could happen if the conditions I spoke about occurred. We just have to be aware it COULD happen. So can a tornado.
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Direct Link To This Post Posted: 30 Jan 2020 at 11:06pm
Why not make a box with a 30A breaker in it to connect to the dogbone.  On the down stream side it can have a 30A plug into which you can plug your 30A cable.  Go from 50A to the box with the breaker, and then to your trailer.  The risk is still there between the 50 amp plug and the length of the dogbone wire, but on the other side of the 30A breaker you should be protected.  If you catch the dogbone wire on fire for lack of 50A protection it's not likely to hurt anything but the dogbone. Presumably the dog bone wires are of a gauge that they can handle the 50A input for the distance to the box.
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Direct Link To This Post Posted: 31 Jan 2020 at 7:22am
Originally posted by Pod_Geek

So I continue to be somewhat confused by the 50-to-30 dogbone thing.  I found this:

The option to run a 30-amp recreational vehicle, or RV, from a 50 amp outlet is useful to many RVers. To avoid catastrophic damage to appliances, equipment and wiring circuits, and a real danger of fire, the amperage must be stepped down to 30 amps. This is easily done, by using a 50-male to 30-female connector, referred to by RVers and manufacturers as a "dogbone" connector, because it has two bulbous terminals joined by a short, slender cord. Dogbone adapters comprise a heavy-duty three-conductor wire between a 50-amp plug and a 30-amp outlet. They work by leaving one of the 50 amp outlet's two positive 120-volt legs unconnected to the 30-amp outlet.


So if this is correct and the dogbone actually steps the current down to 30 Amps right out of the pedestal, is there really any danger?



The claim is bogus. A full 50 Amperes is available to the 30 Amp connector. MCarter is correct. The real world risk is minimal but not zero. BTW I use a dogbone adapter and sleep very well Smile.
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Direct Link To This Post Posted: 31 Jan 2020 at 8:06am
Yes, that claim is nonsense. Overcurrent protection requires a circuit breaker of fuse, so Lostagain’s solution would work.

I just saw this on NorthernTool’s website. It appears to have an inline 20A breaker, not a Gfci. 20A should be fine for our trailers, with the possible exception of running the microwave and the a/c at the same time. It should be located as close as possible to the pedestal.

For the price it might be a good solution even if you had to change out one or the other connectors to make it compatible with your other cords and adapters. I might be tempted to cut off both ends, get a 50A plug and put it on one end, and a 30A on the other so it would replace the dog bone and connect directly to the trailer shore power cord.

https://m.northerntool.com/shop/tools/product_200722091_200722091?&utm_source=google_PPC&utm_medium=NT%20DSA%20Feed&utm_campaign=DSA%20Feed&utm_content=&gclid=Cj0KCQiAvc_xBRCYARIsAC5QT9mSyXx-jxpvWeFQytjcIQ-hF5i7qWr9iO_103AaBVH7GOKJVC8mf8EaAlrIEALw_wcB&gclsrc=aw.ds
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