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50 Amp From 30 Amp And 20 Amp Circuits


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#1 wigginsjsr

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Posted 09 July 2012 - 04:53 PM

Has anyone had experience with the electrical device which claims to provide 50 amps by connecting it to a 30 amp plus a 20 amp circuit or by connecting to two 30 amp circuits?

It is just too hot to use only 30 amps, but some campgrounds only offer 30 amp service, particularly up north.

Is this device a practical solution?

Thanks for your input.
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#2 wolfe10

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Posted 09 July 2012 - 05:00 PM

First, even if it works in a particular campground, it would provide HALF the power of a regular 50 amp outlet. A 50 amp outlet has TW0 50 amp hots so it provides 100 amps of available power. 20 plus 30 is 50 or one half a regular 50 amp.

Second, electric codes for a LONG time have called for GFI protection for any 15 or 20 amp outlet. If the 15 or 20 amp outlet is a GFI protected, this device will not work-- it instantly trips the GFI.

Are there some older CG's that are not GFI protected-- a few.

But, many of these older CG's have limited power and view the cheaters as just that-- cheaters.

Check with CG's you are considering to see if they are allowed and their 15/20 outlets are not GFI protected.

Brett
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#3 kingfr

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Posted 09 July 2012 - 05:16 PM

To answer your specific question, yes it works if: 1 - There is no GF protection on the 20 AMP circuit, and 2 - There is a circuit with a large enough breaker feeding the pedistal. I have seen more than one pedistal with a 30 amp and a 20 amp plug have only a 30 amp breaker feeding it. If you are able to operate this way, you still have to practice energy management, but you can run two A/C untis with this setup. FWTW we have been running this way since March, and yes, the CG is aware that that we are doing it.
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#4 wigginsjsr

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Posted 09 July 2012 - 07:52 PM

Sounds like it will work sometime and not always. I would notify the CG if I were to use this method, but I certainly don't consider it "cheating." The CGs have the option to upgrade to current standards to maintain their business. I don't stay where there is only 30 amps unless there are no reasonable options.
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#5 RVerOnTheMove

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Posted 09 July 2012 - 08:37 PM

You may have gotten some information that you did not clearly understand. Brett gave you the exact correct information. You CANNOT get 50 amp service by plugging into a 20 and a 30 amp circuit. 50 amp service give you 50 amps on each leg of your coaches electrical circuits or 100 amps. Even if you could get that combiners to work (and it's unlikely that you will) you would only have a total of 50 amps available with 20 amp being available on one leg and 30 amps available on the other (not 40 amps on any leg).
What can work very well if is you have 2 - 30 amp circuits to plug that adapter into. In this case there is no GFCI involved and you would have 30 amps available on each leg or a total of 60 amps.
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Bill

#6 bizsmith@yahoo.com

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Posted 10 July 2012 - 06:10 AM

The replies have said it all. If you have GFI on the 20 amp breaker, forget it. I have one I'll sell cheap.

I have found two places I could use it in about seven years.

Those two places have upgraded to GFI on the 20's so it wouldn't work there now.
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#7 desertdeals69

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Posted 17 July 2012 - 11:39 AM

I have been using my "cheater box" that I have designed, at the current campground we are at for the past 2 weeks. We are in northeast Ohio and its been in the 90s on occasion. Both airs are running just fine off the pedistal which has a 30 and a 20 gfi. As I have posted before it is possible. Everything in the coach is wired electrically correct to allow this type of connection.
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#8 TBUTLER

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Posted 17 July 2012 - 01:27 PM

Another factor is that some coaches (ours is an example) have a computer (intellitec) which analyzes incoming power. If the two hot feeds are in the same phase (i.e. same incoming line or even two incoming lines that are same phase) it reads the power as 110V and will not allow more than 30A usage. The computer automatically adjusts the load on the line if we are near exceeding the incoming power. In other words it shuts off our appliances in a prearranged order to keep our usage from tripping the breaker on the campground post. We were in a campground where the 50A current was wired from feeds that were in phase and all we could get was 30A power. If the two legs are out of phase the computer will read the current as 220V (nothing in the coach uses 220V) and we get 50A usage. I don't know how the computer would react if one leg was 20A and the other 30A but I know that if the two are in phase it will not allow more than 30A usage. I am guessing that most 30A/20A boxes/posts are wired from a single line which would be a single phase feed.

We are struggling with 30A power from time to time this summer. There are many things that can be done to reduce the load that the sun puts on the air coinditioners. Using awnings, sun screens, curtains, etc. can limit incoming heat through windows. Also parking position can help. Park facing north if at all possible that keeps the sun off the windshield as much as possible. Sun on our rear end warms the engine and our closet. Much better insulated than the windshield. I also make a habit of opening the engine compartment when we park after driving to help vent engine heat away from the motor home. I do the same with the generator when it has been running before we park. We also run the air to lower the temperature early in the morning to get a "running start" on the heat of the day. We have a Vornado compact floor fan which we carry with us all the time. It helps to give the air some additional movement. Limiting indoor cooking other than the microwave also helps. Think about other appliances which get hot during use, hair dryers, TV's, etc. Finally, eliminating as much moisture from the motor home will assist the air conditioners with their work. Removing water from the air takes a good deal of the cooling capacity of the air conditioner. Shower at the park showers, dry towels and swimwear outdoors, if you shower in your rig, squeege the shower walls and floor to get the water down the drain. Don't boil water on the stove. All these things will help the air conditioner keep you cooler.
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#9 desertdeals69

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Posted 18 July 2012 - 03:19 PM

What I am using will work on most non computer controlled coaches. When I plug in my 20 amp cord I have an automatic transfer switch which energizes the rear air and a couple of outlets. I have about $65 invested including the 30 foot 12/3 cord and switching relay, etc.
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#10 RVerOnTheMove

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Posted 18 July 2012 - 08:09 PM

I doubt that your setup can be translated into usable information for any other RVer. Since you did your own coach conversion to make your 30 amp coach use 50 amp and since you built your own "cheater box" to work with the system you designed, it's unlikely that a production cheater box would work as you describe with an RV with a production 50 amp service.
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#11 desertdeals69

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Posted 19 July 2012 - 02:28 AM

I know a production cheater box won't work, thats why I had to design a different way of doing it. With a couple of changes it will work with a production coach because electricity is electricity. Its really pretty simple.
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#12 mrboyer

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Posted 19 July 2012 - 07:45 AM

Do you have or can create an electrical diagram for the device you have designed?
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#13 desertdeals69

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Posted 19 July 2012 - 10:26 AM

I would love to but because of legal liability issues I can't. Something that is not very well known is that if you modify any manufactured product you become, in the eyes of the law, legally liable if a problem results in a court case. I was in the RV and marine repair business for over 50 years and that is what was preached at all of the service schools when changing anything on your own that was different than the way it was manufactured. If anyone would like to see it in operation let me know as we are headed towards the Boston area, Sturbridge to be exact.
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#14 chucknewman

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Posted 19 July 2012 - 08:56 PM

What desertdeals69 says is correct. The mod is fairly simple and can be done per ANSI RV code. I did so in a bus conversion. But would not do so in someone else's coach. The key is you are not splitting or combining anything at the post. You're splitting one AC feed or other loads away from the coach's sub-panel distribution -- when necessary. Hence no differential current imbalance to trip a GFR at the post.

On our present coach we just don't need it. If we spend one or two nights somewhere 30A is fine. But most of the time we stay somwhere two to six months or more. And we may be running one AC, the microwave, coffee pot, washer-dryer, electric HWH, and/or one or two space heaters if it's cold. If they don't have 50A we go and spend our money at a park that does.

I built a dual 30A plugs to a 50A receptacle in a box and have never used it.
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#15 RVerOnTheMove

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Posted 19 July 2012 - 10:11 PM

What is being referenced above might be confusing to the casual user (reader). You "can" make a cheater box work if you do some custom wiring to your coach and your box. For the 99.99% of the rest of us, the reality is that a production cheater box will not work with a production coach 50 amp circuitry.
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#16 desertdeals69

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Posted 20 July 2012 - 07:01 AM

I think we've beat this subject to death. To say that you can't get 50 amps from a pedestal with a 30 amp and a 20 amp gfi is not correct, however if that's what you believe that's fine. For the rest of us we will continue to enjoy using 2 airs when needed.
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#17 wolfe10

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Posted 20 July 2012 - 08:18 AM

I think we've beat this subject to death. To say that you can't get 50 amps from a pedestal with a 30 amp and a 20 amp gfi is not correct, however if that's what you believe that's fine. For the rest of us we will continue to enjoy using 2 airs when needed.


I would state that just a little differently: You can't use an off the shelf adapter to get 50 amps from a pedestal with a 30 amp and a 20 amp GFI.

A knowledgeable electrician can re-wire a coach to split the circuits in the coach to use both the 30 and 20 GFI outlets to provide up to 50 amps of 120 VAC-- HALF the amps a standard 50 amp outlet provides.

Brett
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#18 chucknewman

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Posted 28 July 2012 - 11:25 AM

Yep! It is what it is.
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#19 desertdeals69

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Posted 21 August 2012 - 05:31 PM

Just checked into the Wilmington Oh Thousand Trails which has 30 and 20gfi on the pedistal. Plugged in both the 30 and 20 amp cord and am running both airs.
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#20 RVerOnTheMove

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Posted 21 August 2012 - 06:55 PM

DD69,
I think we all understand that your custom wired coach with a custom wired combiner works with your setup.
This is not going to be the case for anyone using a factory wired coach and a mass produced combiner.
Additionally, it's important that those reading don't confuse the topic listing (50amp from 30 and 20 amp) with the ability to make a 30 amp coach a 50 amp coach. In your setup you will have 30 amps available on one leg of your wiring and 20 amps available on another. A 50 amp coach has 50 amps available on each leg for a total of 100 amps.
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