Using Adaptors for power

[Camper_bob]

Originally Posted by Jmooney

I would not convert a 50 amp service down to a 30 amp cord. But you can convert a 30 amp service up to a 50 amp cord cant you?

Why not? I have 50A service (though it's not really necessary as I have the 2nd AC prep, but not the actual unit), and I imagine it's only a matter of time before I'm faced with a site that only has 30A service. I bought a dog bone at the dealer on delivery day specifically for that contingency, though I have yet to use it.

As long as you're not trying to pull too much amperage, you're okay right? And you'll trip the breaker at the post if you do try, right?

[Jmooney]

Originally Posted by Camper_bob

Why not? I have 50A service (though it's not really necessary as I have the 2nd AC prep, but not the actual unit), and I imagine it's only a matter of time before I'm faced with a site that only has 30A service. I bought a dog bone at the dealer on delivery day specifically for that contingency, though I have yet to use it.

As long as you're not trying to pull too much amperage, you're okay right? And you'll trip the breaker at the post if you do try, right?

I'm thinking its the end at which you are converting.


If your TT has 50 amp service, the master breaker inside will be rated at 50 amps

If you plug into 50 amp service, and convert down to a 30 amp cord, then pull 49 amps, neither breaker will blow, but the 30 amp cord will get very hot.

The other way: you plug into a 30 amp service, and convert up to a 50 amp cord. If you pull 30 amps, the breaker on the post will trip, but the cord will not have a problem....

No?

[t2daniel]

Just be careful what you plug into. A true 20A adapter would have 1 of the terminals spun 90° so the adapters allow you to plug into a 15 A or a 20 A circuit. Outdoor plugs are most likely a GFCI which can take a true 20 A plug but might be wired on a 15 A circuit. I have a 20A GFCI receptical, but it is a true 20A circuit with 12 gauge wire to the panel and a 20A breaker. I have run my AC with no issues, but if you are running all kinds of other things in the TT when the AC turns on, you could have issues with too much voltage drop.

If you are using an adapter, be smart about it and realize there may be some restrictions.

[Camper_bob]

Originally Posted by Jmooney

I'm thinking its the end at which you are converting.


If your TT has 50 amp service, the master breaker inside will be rated at 50 amps

If you plug into 50 amp service, and convert down to a 30 amp cord, then pull 49 amps, neither breaker will blow, but the 30 amp cord will get very hot.

The other way: you plug into a 30 amp service, and convert up to a 50 amp cord. If you pull 30 amps, the breaker on the post will trip, but the cord will not have a problem....

No?

Yeah, that sounds kind of right. Except that when you adapt 50 amp at the post down to a 30 amp plug, you actually only get 25 amps because the adapter only uses one side of the 50 amp service. At least that's the way I understand it. This would be an issue if a 30 amp rig pulls into a 50 amp only space, or a 50/30 where the 30 looks a little shady from too much use so you go into the 50 amp side because it's not as beat up. And if I'm correct, the bigger issue in that case is under-delivery of power rather than over loading the adapter.

But I don't have to worry about that because I have 50 amp service, so I can only go down.

[clutch]

Our trailer is 50 amp and when on the road I always use an adapter so I don't have to deal with the heavy 50 amp cord. I bought a 30 amp cord for travel and for the occasion when a 50 amp wasn't available.

Most people that have had trouble with a 15 or 20 amp hook up most likely are using too light of a cord. 25 or 50 ft of number 12 cord just won't do.

[Jmooney]

Originally Posted by Camper_bob

Yeah, that sounds kind of right. Except that when you adapt 50 amp at the post down to a 30 amp plug, you actually only get 25 amps because the adapter only uses one side of the 50 amp service. At least that's the way I understand it. This would be an issue if a 30 amp rig pulls into a 50 amp only space, or a 50/30 where the 30 looks a little shady from too much use so you go into the 50 amp side because it's not as beat up. And if I'm correct, the bigger issue in that case is under-delivery of power rather than over loading the adapter.

But I don't have to worry about that because I have 50 amp service, so I can only go down.

I'm pretty sure that you have 50 amps on both legs.

So even though you have gone to a single phase, you still have 50 amps, and potentially pulling 50 amps through a 30 amp cord is never a good idea. The 30 amp wire becomes a " 30 amp fuse " if you will, just a very dangerous one.

The rule should be that the smallest wire used between post and power center dictate the largest service / breaker that you should connect too at the post.

[Bob Landry]

Originally Posted by Camper_bob

Yeah, that sounds kind of right. Except that when you adapt 50 amp at the post down to a 30 amp plug, you actually only get 25 amps because the adapter only uses one side of the 50 amp service. At least that's the way I understand it. This would be an issue if a 30 amp rig pulls into a 50 amp only space, or a 50/30 where the 30 looks a little shady from too much use so you go into the 50 amp side because it's not as beat up. And if I'm correct, the bigger issue in that case is under-delivery of power rather than over loading the adapter.

But I don't have to worry about that because I have 50 amp service, so I can only go down.

There are lots of misconceptions and lack of understanding about 50A service. 50A is actually 100A, two 120V legs each capable of supplying 50A. That's the reason 50A shore cords are made with 6ga cable. 30A cable is 10ga. There is no reason not to use a 30-50 adapter, but use the dogbone made by Marinco or Camco. The small "hockey puck" adapters are famous for burning up and taking the power cord with them. When you plug a 30A adapter into 50A service, you still have 50A available at the pedestal but the 30A breaker at your power panel will limit you to 30A. Contrary to popular belief, the pedestal is not going to try to "push" 50A into your rig.
If your trailer is set up for 50A and you use an adapter to plug a 30A cord into a 50A service because you don't want to wrestle a 50A cord then you are not protected. The safe way to do that would be to build a breakout box protected with a 30A breaker. Many people use ad adapter to plug their 30A rigs into 50A because the contacts on the 50A plugs are usually in better condition, and there is no problem in doing that.
I added a second 30A service to my trailer and use a breakout box plugged into the 50A outlet and nothing overheats.

[t2daniel]

Originally Posted by Bob Landry

There are lots of misconceptions and lack of understanding about 50A service. 50A is actually 100A, two 120V legs each capable of supplying 50A. That's the reason 50A shore cords are made with 6ga cable. 30A cable is 10ga.

Bob,

Just for my understanding. When a trailer has a 50 A plug it is 50 A 220V (total of 50 A on each 110V leg)? The reason I ask is my 30 A in my White Hawk is 30 A 110 V. That is a huge step up from 30 A to 100 A!!

[Bob Landry]

Originally Posted by t2daniel

Bob,

Just for my understanding. When a trailer has a 50 A plug it is 50 A 220V (total of 50 A on each 110V leg)? The reason I ask is my 30 A in my White Hawk is 30 A 110 V. That is a huge step up from 30 A to 100 A!!

That's correct, but 30A service consists of a single 120V leg, a neutral, and a safety ground. 50A service is two 120V legs each providing 50A, a neutral, and a safety ground, so it's two wire as opted to a single one. The 50A is wired with 6ga wire, thus allowing 50A per leg.

[wwsmith111]

Bob is correct. 30 amp service = 3600 watts vs. 50 amp service = 12,000 watts of power. Big difference. I recommend that everyone should study up on this somewhat in order to have a basic understanding of how RVs hook up to power as it isn't straight forward especially if you plan on using adapters. I think this is why Jayco says not to use adapters because one can get into trouble if one doesn't know what one is doing. I have just about all the common 50, 30 and 15/20 amp adapters going both ways and have used them all from time to time. I test the service I am about to hook to before hooking to it with a tester and a volt meter. I measure each hot leg to neutral and ground and if a 50 amp service I measure between each hot leg for 240 volts. Old camp grounds and State Parks are notorious for their power problems. But I have had problems at brand new RV parks as well with bad neutrals or grounds. I have a tester and plug in volt meter that I leave plugged in inside the camper so I can monitor it. It is amazing how much the voltage fluctuates and I have seen it get too low and too high.

[havnfun]

Bob Landry- I went to CW today and bought 2 dog bones based on your post about the adaptor burning cords etc. You definitely got my attention! That's why I read the JOF as much as possible...so I can learn from you knowledgable experts in the RV arena. Thanks all.

[Jmooney]

So what I think I understand Bob to say is that you can convert down from a 50 amp source to a 30 amp wire, provided that you have a 30 amp breaker in line somewhere, either because your TT power center is 30 amps, or you have added an inline 30 amp breaker.

But a 50 amp feed to a 50 amp power center, (breaker) running through a 30 amp wire is still a potential problem


Am I clear on that?

[Bob Landry]

Originally Posted by Jmooney

So what I think I understand Bob to say is that you can convert down from a 50 amp source to a 30 amp wire, provided that you have a 30 amp breaker in line somewhere, either because your TT power center is 30 amps, or you have added an inline 30 amp breaker.

But a 50 amp feed to a 50 amp power center, (breaker) running through a 30 amp wire is still a potential problem


Am I clear on that?

You are correct. There would be no protection for the 10g a wire which is only rated for 30A.

[Jmooney]

Thanks Bob. This was a long thread with lots of counter points. In the end I wanted to make sure both I, and a future casual reader , would get the most important message: how you do this is important, not doing it right could be very dangerous.

Just cause they sell adapters , doesn't make it safe.

[Parcany]

Been thinking about going to a state park with only 50 amp. So what I have to do is hook up a dog bone to the 50 amp source, [50 to 30] then hook up surge protector 30 amp then hook up trailer cord 30 amp. Time we are planning to go is Oct so air conditioning will not be used. Is this right.

[Jmooney]

What is the rated breaker in the power center in your TT.

If it's 30 amps, or less, , you are fine, it will provide protection, cause the TT can't draw more than 30 amps without tripping the main breaker in the TT power center, therefore, never drawing more than 30 amps through the wire used to connect to the post.

You will still need an adaptor to go from a 50 amp plug to a 30 amp cable to the TT

The risk that I was describing is when you have a 50 amp breaker at both ends, and a 30 amp wire in between

[Jmooney]

Power surge or clean power at the camp ground is a different problem altogether, and if you have concerns, then you need to add appropriate surge and voltage protection devices as Bob described

[Parcany]

J- here is what I have. Trailer 30 amp. Plug in power at campground 50 amp. Dogbone goes from 50 amp to 30 amp, then hook up 30 amp surge protector then hook up 30 amp trailer.

[Jmooney]

Originally Posted by Parcany

J- here is what I have. Trailer 30 amp. Plug in power at campground 50 amp. Dogbone goes from 50 amp to 30 amp, then hook up 30 amp surge protector then hook up 30 amp trailer.

Excellent!

[cekkk]

I'v kept our Eagle plugged into the barn with an adapter most of our short summers for three years without a problem. That said, even though I'm only running the fridge, I pull out the 30 amp cable so it's not curled up (thanks, Parcany) and use a short, heavy gauge extension cord.

As the lawsuits pile up it's becoming more and more difficult to know whether an instruction in a manual is instructing us on how to use a product or is butt cover from the legal department.