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Installing/understanding 30 and 50-amp RV service
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TOPIC: Installing/understanding 30 and 50-amp RV service

Installing/understanding 30 and 50-amp RV service 3 years, 10 months ago #14863

This is a great website to help you understand the differences between 30 and 50 amp electrical services you will encounter on your RV and at campgrounds. It shows you how to make inexpensive outlet testers, so you can test BEFORE you plug your camper into a campground service, that could possibly damage your trailer.

It will help everyone who may want to install RV service at their house for their campers.

I am going to make this topic a sticky.

www.myrv.us/electric/

I really liked the part on how to make an inexpensive, easy-to-read, 30 AMP outlet tester. It is so much easier to understand for our members who aren't familiar with using a digital or analog multi-tester.

www.myrv.us/electric/Pg/tester_30amp.htm


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Last Edit: 3 years, 10 months ago by LSUFan.

Re: Installing/understanding 30 and 50-amp RV service 3 years, 9 months ago #14898

This is my understanding of 50 amp service for trailers wired to utilize it (Ex. Selgoja's mansion on wheels). Let me see if I can put it in Layman's terms without getting too technical.

Most experienced camper owners fairly understand the common 30 amp service. It's 110 volt, and you are limited to using a total 30 amps of electrical stuff in your trailer at the same time. Most have learned that you have to turn some things off in your trailer.... when using toasters, hair dryers, and other things that take a lot of electricity to power or you will trip the breaker(s).

Now with a 50 amp service, common sense says that you now have 50 amps of total power, as the name applies, versus the 30 amp previously discussed....or 20 amps more than 30 amps. (20 + 30 = 50)

Now the fun part: You have more than 50 amps total when hooked to a 50 amp service. This 50 amp service is 220 volt (2 X 110), but the service is actually split into two 110 volt sides....EACH with 50 amps.

So, in reality you have TWO (2) fifty amp lines supplying power to your trailer....or a total of 100 amps when connected this way.....or as some voltage monitors say L1 and L2. This is over three times as much as a 30 amp service.

Because you have 100 total amps (over 3 times as much as a 30 amp), you can run all kind of electrical stuff at the same time now. 2 air-conditioners, water heaters, microwaves, toasters, hair dryers. etc. You are still going to be limited to the individual circuit breakers for each outlet. It's so much better than a 30 amp service.

Unless you get into some higher-end coaches, nothing in your travel trailer actually uses 220 volt, but everything works off of 110 volt either on your L1 or L2 sides. This is the part that confuses a lot of people.

The sides (L1, L2) share a common 50 amp double pole breaker and plug-in in the campground pedestal, so if there is a problem on either side, then the breaker trips....shutting down both sides. It might not be as confusing if the breaker had printed on it 50(x2).


Hopefully, this gives an easy understanding of the differences between 30 amp and 50x2 amp trailer service. It also is easy to understand why some campgrounds charge more for using the 50 amp service, as those campers have the potential to use over 3 times as much electricity as their 30 amp neighbor.
__________________


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Last Edit: 8 months, 2 weeks ago by LSUFan.
The following user(s) said Thank You: Dawson

Wiring for 30 amp service 3 years, 9 months ago #14904

I frequent several camper trailer forums. One of the things I read about that happens many times over, is when travel trailer owners decide to install a 30 amp service at their house so they can plug their trailers into it.......and wire it wrong. This mistake is made by professional electricians (who don't have experience with the 30 amp travel trailer plug/outlet) as well as many do-it-yourselfers.

The 30 amp trailer service is 110/120 volt..........and is NOT 220/240 volt. I repeat, it is 110 volt. The travel trailer plug is what confuses most people, as they are used to weird looking pronged plugs being 220 volt. Don't be confused. It is 110 volt.

When you wire an outside outlet for 220 volts and plug your 110 volt trailer into it, you are going to blow up (and it will most likely smoke) your DC converter right off the bat. This converter is what converts the 110 volt AC current into 12 volt DC current. Your lights, fans, battery charger, heater, parts of your fridge, and other things run off of DC current. If you blow up your converter, then nothing works in your trailer.

Also, you can ruin any appliances that run of off 110 volts...like your air conditioner, television, microwave, and/or anything plugged into an electrical outlet inside your trailer...........if you hook up to a 220 volt service.

As you see, you can have disastrous results if you don't have your outside service wired for 110 volt.

To make sure this doesn't happen to our members here (should they decide to have a 30 amp service installed at their house) I am adding a pdf file that everyone can print out that shows how to correctly wire for the 30 amp travel trailer service. You can use this as a reference guide, or hand it to an electrician who you may hire to install it for you.


This attachment is hidden for guests. Please log in or register to see it.


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Last Edit: 3 years, 9 months ago by LSUFan.

Re: Wiring for 30 amp service 3 years, 9 months ago #14910

Very good article and the PDF file is very accurate, including the wire size needed for the length runs. One word of advice would be to wire up the receptacle first before hooking up to the breaker to insure that end will not be hot. Good job LSUFan.
The glass is not half full or half empty, only twice as large as it needs to be.

Re: Wiring for 30 amp service 3 years, 9 months ago #14911

I'm sure glad the i did it correct. however, where was this info when i did mine.

i just looked on the packages. and used a plug on both ends.
Last Edit: 3 years, 9 months ago by fishingmcman.

Re: Installing/understanding 30 and 50-amp RV service 3 years, 9 months ago #14913

Most experienced camper owners fairly understand the common 30 amp service. It's 110 volt, and you are limited to using a total 30 amps of electrical stuff in your trailer at the same time. Most have learned that you have to turn some things off in your trailer.... when using toasters, hair dryers, and other things that take a lot of electricity to power or you will trip the breaker(s).


That's Patches...& that's why you see an orange electric cord running from the pedestal thru my window when I'm using my electric skillet!


Support bacteria--it's the only culture some people have.

Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16408

That would require two separate 50 amp breakers on the same bus bar. But your 30 amp plug doesn't have two poles. If your way worked you would create what is called a multi line branch circuit but by using the same bus bar you would create a neutral overload. im trying to figure out if the adapter for the 50 amp four plug wore probably only uses one side of the 50 amp plug because there are only three prongs on the other end. The reason it works for you is because it is idiot proof and won't allow 220 back on the 30 amp side. Or in your case the 120 volt that you have on each of the L1 and L2 only one side is being used. Take a volt meter set it to check continuity. That's where it beeps when you touch them together. My bet is that one of the lines on the 50 amp plug doesn't run threw the adapter, but I'll find out tomorrow

Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16409

A 220 volt plug 50 amp four prong can have be plugged in and my guess is that it only uses one hot phase the neutral and ground. I am putting in a 50 amp plug with four prong and the adapter to step down to 30 amp only has three prongs. My guess is that I could take 2 50 amp 110 breakers and put on the same bus bar to prevent the chance of 240 getting into the camper but I'm positive that even if the plug is 50 amp 220 and the adapter has only three prongs that one of the hot phases can't get threw. In other words idiot proof. However this doesn't matter because stepping down from 50 to 30 means everything from the adapter is still only rated 30 amps so just because you have more kick from the plug you are likely to cause more resistance at places like where the 30 amp plug meets the 50. I bet those of you who use them a lot notice at your plug it probably gets hot. I won't know till tomorrow but my guess is the adapter is idiot proof. For example if you were visiting family you could plug in where their range is and it won't matter that it's a 220 volt plug because the adapter will only use one hot one neutral and a ground if they have it.

Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16410

Louzy wrote:
That would require two separate 50 amp breakers on the same bus bar. But your 30 amp plug doesn't have two poles. If your way worked you would create what is called a multi line branch circuit but by using the same bus bar you would create a neutral overload. im trying to figure out if the adapter for the 50 amp four plug wore probably only uses one side of the 50 amp plug because there are only three prongs on the other end. The reason it works for you is because it is idiot proof and won't allow 220 back on the 30 amp side. Or in your case the 120 volt that you have on each of the L1 and L2 only one side is being used. Take a volt meter set it to check continuity. That's where it beeps when you touch them together. My bet is that one of the lines on the 50 amp plug doesn't run threw the adapter, but I'll find out tomorrow


Louzy, 50 amp 120/240 volt split phase service has two hot lines, a shared neutral, and a ground. Each hot line is utilized by the RV as a separate 120 volt lines and never together for 240 volts. The shared neutral works due to load balancing. It's hard to get your mind on this but this link will better explain 120/240 volt split phase service to you and the all important load balancing affecting the neutral (no overload). A double pole breaker is in essence actually two separate breakers (one on each bus). They are tied together, so that if there is an overload on one circuit, with the shared neutral, it trips both legs at the same time.

This link will help you understand the load balancing and shared neutral. I'll explain the adapters in a following post.

www.rvtechmag.com/electrical/chapter3.php

Here is also a couple schematics that may help you see what is being discussed:





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Last Edit: 8 months, 2 weeks ago by LSUFan.

Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16411

Here is also a link I refer many camper to in an RV forum that I am a site team member of. it has a lot of useful information

www.myrv.us/electric/

Now for your adapter. If you are using an adapter to plug into 120/240 volt 50 amp split phase outlet...then to go to a 30 amp single phase....then the adapter just takes as you surmised one leg (say L1) of the the two legs available, and provides power. It use a ground and neutral too. The second leg is just terminated inside the adapter and has nowhere to go. You will have 50 amp capability from the outlet into the RV's electrical panel, but would then be limited to only 30 amps by the RV's main power circuit breaker from there on.

If you are plugging a 50 amp RV into a 30 amp outlet (which some places only have 30 amp outlets), then what the adapter does is jumps the only hot leg (say L1) over to the L2 side too. This way your 50 amp RV will have both buses fed by the same 30 amp L1....and you will have power to both legs but 30 amps total....instead of the 50 amps per leg or 100 amps total as normal when connected to a 120/240 volt 50 amp split phase service.

This diagram may help you envision that scenario:



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Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16413

I invite any/all mutual RV'ers/geocachers over to www.forestriverforums.com.

We have a wealth of information on about all camping/RV subjects. My handle there is wmtire.


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Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16414

Louzy wrote:
For example if you were visiting family you could plug in where their range is and it won't matter that it's a 220 volt plug because the adapter will only use one hot one neutral and a ground if they have it.


If you don't want to fry your converter, microwave, and television (and potentially more).....then I strongly advise reading all the links in the www.myrv.us/electric link.

The older appliance 240/220 volt outlets are only three wire...as well as many welding outlets. That is a two 120 volt hot lines and either a neutral (no ground) for appliances...or a ground (no neutral for) for welders.

You try to plug into these type of outlets, then most likely you are going to be putting a 120 volt hot leg onto either your neutral or ground wire feeding the 30 amp....... as well as the other 120 volt hot leg feeding the normal hot line. You will have 240 volts feeding into the RV this way and WILL burn stuff up this way.

If you plug into any 240 outlet with an adapter, it has to have 4 correctly connected wires to function. Two individual 120 volt lines, one neutral and one ground.

Please, Please, read the welder and appliance tabs on the rv.us link above before damaging anything. It will also tell you what you must do in order to use either of these type outlets for your RV.

We have had many professional electricians wire the outlets wrong in the forestriver forums and horror stories abound of people messing up their RV's by not knowing better. This is why I started this thread here in the first place.

Please take the time to learn this.


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Last Edit: 8 months, 2 weeks ago by LSUFan.

Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16415

Why use 2 240 volt plug. If you say that a 50 amp plug on an rv has four prongs why design it to fit into a plug that can put out 220 when it would be simple to not have that happen. I'm an electrician a master electrician and I'm just saying that people get paid to think up these things. I seen a 50 amp to 30 amp adapter it could be plugged into a 220 and not put that on the rv. There is no point of having to hot 110 prongs on a cord. If you put those on separate breakers and on the same bus bar you would create a neutral overload. I'd like to see the schematics for a 50 amp rv. Why use a plug that can be plugged into something that would ruin your rv. Why not use a different plug. I'll read your suggestion but the picture I seen showing a 4 prong on one breaker and both lines on the plug were on the same phase. In that case if both prongs were being used you couldn't step down to a three wire 30 amp adapter. The 50 amp four prob I checked today only used one of the hot prongs it could have been plugged into a 220 plug at grandmas range and done no damage to the rv. Although it had four wires only three of them came inside the fourth was just there for looks. As well as the adapter for 50-30.

Re: Installing/understanding 30 and 50-amp RV service 8 months, 2 weeks ago #16416

Louzy wrote:
Why use 2 240 volt plug. If you say that a 50 amp plug on an rv has four prongs why design it to fit into a plug that can put out 220 when it would be simple to not have that happen. I'm an electrician a master electrician and I'm just saying that people get paid to think up these things. I seen a 50 amp to 30 amp adapter it could be plugged into a 220 and not put that on the rv. There is no point of having to hot 110 prongs on a cord. If you put those on separate breakers and on the same bus bar you would create a neutral overload. I'd like to see the schematics for a 50 amp rv. Why use a plug that can be plugged into something that would ruin your rv. Why not use a different plug. I'll read your suggestion but the picture I seen showing a 4 prong on one breaker and both lines on the plug were on the same phase. In that case if both prongs were being used you couldn't step down to a three wire 30 amp adapter. The 50 amp four prob I checked today only used one of the hot prongs it could have been plugged into a 220 plug at grandmas range and done no damage to the rv. Although it had four wires only three of them came inside the fourth was just there for looks. As well as the adapter for 50-30.


I'm not following you anymore. All the schematics as well as the distribution panels for the house/campground...as well as the 50 amp distribution panels for the RV are shown above.

If you are a master electrician as you say, then you should know how a breaker box is set up and how a double pole breaker grabs 120 volts from L1 and 120 volts from L2. The pictures above in post #16410 shows how a 50 amp RV utilizes the L1 and L2 separate. The links I also gave, explain this. Don't know what else I can do to help you. It's all there.

Here is a pic of 50 amp electrical distribution panel inside an RV. It has a 50 amp double pole main breaker (which is two breakers) that provides 120 volts 50 amps to L1 and the same holds true for L2...and it is 100 amps total.



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Last Edit: 8 months, 2 weeks ago by LSUFan.

Re: Installing/understanding 30 and 50-amp RV service 8 months, 1 week ago #16428

LSUFan I want to say thank you for all the information you have posted and shared. The graphs are great. I am an electronics tech, but educating myself more on AC electrical. I have an old 1965 Scotty Tonga Camper (Canned Ham) that I am partially restoring. The electrical in it is terrible compared to todays standards. I just want to update it some.

So, once again thank you for all that you have shared.

and

Gigem Aggies.

Edward Brackin
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