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Old 10-13-2013, 09:49 AM   #71
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I have a question about the difference between 30 and 50. My coach has power to everything when on 30amps (except the rear a/c maybe, I'll have to check it later) so if when plugged into 50 amps what does it power and or where is it separated because it would have to be or it would be a dead short? Or does it just give you more load capacity on that one leg? Inquiring minds would like to know.
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Old 10-13-2013, 10:07 AM   #72
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Originally Posted by jeepfreak View Post

I have a question about the difference between 30 and 50. My coach has power to everything when on 30amps (except the rear a/c maybe, I'll have to check it later) so if when plugged into 50 amps what does it power and or where is it separated because it would have to be or it would be a dead short? Or does it just give you more load capacity on that one leg? Inquiring minds would like to know.
Since you did not state whether your coach is 30 amp or 50 amp, based on the year and brand I will assume 50 amp.

When you are hooked to 30 amp shore power you are using a 30 to 50 amp Dog-bone. Inside that adapter is where the connections are combined.

A 50 amp pedestal is really TWO 120 VAC 50 amp lines of service using LEG 1 and LEG 2 which are never combined after your shore power cable.

A 30 amp pedestal is only one line of 120 VAC 30 amps. So that one line needs to service BOTH L-1 and L-2 of your coach. That is done inside the 30 to 50 amp Dog-bone.

Now you may or may not have a system inside your coach to monitor how many amps you are using when on 30 amp service. If you do then that device will drop off various devices as you start to exceed the 30 amps available at the pedestal. If you don't then YOU have to monitor what you are using and how much so that you don't burn up your Dog-bone or worse yet something else.

If your coach is 30 amp but wanted to plug into a 50 amp pedestal, there is another Dog-bone that is 50 to 30 amp which takes only ONE leg, either L-1 or L-2 to provide 120 VAC power to your 30 amp coach. Even though there are 100 amps available at the pedestal you will only be drawing a maximum of about 25-28 amps from the one leg.

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Old 10-13-2013, 10:11 AM   #73
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I have a question about the difference between 30 and 50. My coach has power to everything when on 30amps (except the rear a/c maybe, I'll have to check it later) so if when plugged into 50 amps what does it power and or where is it separated because it would have to be or it would be a dead short? Or does it just give you more load capacity on that one leg? Inquiring minds would like to know.
It's done in the 30-to-50 adapter. The 30 amp adapter feeds both legs of the RV. You still have only 30 amp to go around. Nothing different happens in the RV, except maybe some load management decisions.

OOOPs! Richard is faster and more thorough than I
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Old 10-13-2013, 10:27 AM   #74
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I have a question about the difference between 30 and 50. My coach has power to everything when on 30amps (except the rear a/c maybe, I'll have to check it later) so if when plugged into 50 amps what does it power and or where is it separated because it would have to be or it would be a dead short? Or does it just give you more load capacity on that one leg? Inquiring minds would like to know.
30 amp service is just that, 30 amps. You usually can't power both A/C on it and if you can, don't try to make popcorn or toast at the same time. 50 amp service is actually 2 'legs' of 50 amp service or 100 amps total coming into the RV. As long as the wiring in the RV is divided up so you never exceed 50 amps on either 'leg' you'll never trip a breaker. Newer rigs with more electric appliances like Washer/Dryers, electric cooktops, etc. usually have 50 amp service. We just returned from a month long trip in our rig with 50 amp service. I usually just signed up for 30 amp sites since I wasn't going to need both A/C., so it gave us a little savings.

A 30 to 50 amp adaptor just uses one leg of the 50 amp plug and your circuit breakers in your 30 amp RV limit the amount of power you use. You can't 'over power' an RV by hooking up to a higher rated service, just as turning on a 25 watt bulb won't burn out if it's screwed into a lamp usually used for a 75 watt bulb.
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Old 10-13-2013, 12:15 PM   #75
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The formula for calculating watts is amps x volts = watts.
On a 30 amp circuit at 120 there is (in theory) 3600 watts available for use.
On a 50 amp connection there is 6000 watts per leg available x 2 legs or 12,000 watts.
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Old 10-13-2013, 01:47 PM   #76
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30 amp service is just that, 30 amps. You usually can't power both A/C on it and if you can, don't try to make popcorn or toast at the same time. 50 amp service is actually 2 'legs' of 50 amp service or 100 amps total coming into the RV. As long as the wiring in the RV is divided up so you never exceed 50 amps on either 'leg' you'll never trip a breaker. Newer rigs with more electric appliances like Washer/Dryers, electric cooktops, etc. usually have 50 amp service. We just returned from a month long trip in our rig with 50 amp service. I usually just signed up for 30 amp sites since I wasn't going to need both A/C., so it gave us a little savings. A 30 to 50 amp adaptor just uses one leg of the 50 amp plug and your circuit breakers in your 30 amp RV limit the amount of power you use. You can't 'over power' an RV by hooking up to a higher rated service, just as turning on a 25 watt bulb won't burn out if it's screwed into a lamp usually used for a 75 watt bulb.
I'm a little confused on the 30 to 50 amp adaptor. If it just uses one leg wouldn't half the circuits be dead? Maybe I got it backwards. I am taking this to say 30 amp pedestal to a 50 amp plug?
I could see a 50 amp to a 30 amp adapter having only one leg hot, but not 30 to 50.
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Old 10-13-2013, 01:58 PM   #77
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I'm a little confused on the 30 to 50 amp adaptor. If it just uses one leg wouldn't half the circuits be dead? Maybe I got it backwards. I am taking this to say 30 amp pedestal to a 50 amp plug?
I could see a 50 amp to a 30 amp adapter having only one leg hot, but not 30 to 50.
I continue to learn something new daily on this forum.
Already explained by Dr4Film and loulong. 30 amp service is only one hot, neutral, and ground. 50 amp is two hot, one neutral, and ground. The adaptors are wired to deal with it.
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Old 10-13-2013, 03:43 PM   #78
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X2 on BFlinn181 post.

Besides what he stated in his post here is a link that you should BOOKMARK and refer to often.

RV Electric

Then here are two more that you need to BOOKMARK that pertain to the 12 VDC portion of the RV.

The 12volt Side of Life (Part 1)

The 12volt Side of Life Part 2

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Old 10-13-2013, 03:56 PM   #79
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30 amp service is just that, 30 amps. You usually can't power both A/C on it and if you can, don't try to make popcorn or toast at the same time. 50 amp service is actually 2 'legs' of 50 amp service or 100 amps total coming into the RV. As long as the wiring in the RV is divided up so you never exceed 50 amps on either 'leg' you'll never trip a breaker. Newer rigs with more electric appliances like Washer/Dryers, electric cooktops, etc. usually have 50 amp service. We just returned from a month long trip in our rig with 50 amp service. I usually just signed up for 30 amp sites since I wasn't going to need both A/C., so it gave us a little savings.

A 30 to 50 amp adaptor just uses one leg of the 50 amp plug and your circuit breakers in your 30 amp RV limit the amount of power you use. You can't 'over power' an RV by hooking up to a higher rated service, just as turning on a 25 watt bulb won't burn out if it's screwed into a lamp usually used for a 75 watt bulb.

Although there are adapters that allow you to hook up a 30 amp service to a 50 amp pedestal I am very much against doing that except for a very short time period. Possibly if you are stopping overnight at a busy campground which only has 50 amp service available. I really disagree with the other posters who seem to feel that it is very benign to do this. I think you are taking a risk every time you do it.

Keep this thought in mind. EVERY time you hook a 30 amp cable into an adapter and then hook it to a 50 amp pedestal you are hooking a cable into a breaker that can take more current than the cable can handle before it trips. Basically you are turning your cable into a 30 amp fuse. If it gets more current than it can handle through it then it is going to melt with whatever consequences that entails
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Old 10-13-2013, 04:14 PM   #80
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Although there are adapters that allow you to hook up a 30 amp service to a 50 amp pedestal I am very much against doing that except for a very short time period. Possibly if you are stopping overnight at a busy campground which only has 50 amp service available. I really disagree with the other posters who seem to feel that it is very benign to do this. I think you are taking a risk every time you do it.

Keep this thought in mind. EVERY time you hook a 30 amp cable into an adapter and then hook it to a 50 amp pedestal you are hooking a cable into a breaker that can take more current than the cable can handle before it trips. Basically you are turning your cable into a 30 amp fuse. If it gets more current than it can handle through it then it is going to melt with whatever consequences that entails
The 30 amp breaker in the RV prevents you from drawing more than the 30 amp shore cord and adaptor can handle. My house is connected to more power than my power lines can handle, the breakers in the service panel limit how much I draw, same set up as a 30 amp RV plugged in to a 50 amp pedestal.
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Old 10-13-2013, 04:41 PM   #81
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The 30 amp breaker in the RV prevents you from drawing more than the 30 amp shore cord and adaptor can handle. My house is connected to more power than my power lines can handle, the breakers in the service panel limit how much I draw, same set up as a 30 amp RV plugged in to a 50 amp pedestal.
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Old 10-13-2013, 05:20 PM   #82
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I do have a 50 amp RV. So when plugged into a 30 amp using the 50 to 30 adaptor both sides of the RV breaker panel are powered by the same 110 volt leg ? And when plugged into a 50 amp it's feeding 1 leg with 110 and 110 on another phase to the other leg and it's done thru the way the adaptor and or main cord cap is made? is that correct?
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Old 10-13-2013, 05:40 PM   #83
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"And when plugged into a 50 amp it's feeding 1 leg with 110 and 110 on another phase to the other leg and it's done thru the way the adaptor and or main cord cap is made? is that correct?"

30 amp service is divided between both legs of your 50 amp RV shore cord by the adaptor. Each 'leg' of 50 amp service provides 120 v at 50 amps. They are 180 out of phase with each other so the neutral line is still only 'seeing' 50 amps power at any given instant. 50 amp plug and cord both have two 50 amp 'hots', neutral, and ground. No adaptor needed.
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Old 10-13-2013, 05:53 PM   #84
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Thanks ! It all makes sense now. I think I was confused because nothing in the RV is wired for 240 so there couldn't be a dead short .
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