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Old 06-25-2018, 12:08 PM   #21
BB_TX
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Originally Posted by mtlakejim View Post
So if they had the A/Cs on separate legs would you be able to run both at a 30amp site??
Even though there are two hot legs in the trailer, they are both fed by the single leg from the 30 amp park breaker. A typical 15k A/C pulls 15 +/- amps. You MIGHT run two A/Cs at the same time. But even if you could it would be right on the edge of tripping the 30 amp breaker. And that would mean nothing else at all could be on ac power at the same time.

I can run my 15k A/C on a 20 amp house breaker but it will trip a 15 amp breaker.
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Old 06-25-2018, 12:20 PM   #22
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So just to be sure I understand this correctly, are you saying that 30amp service is just that but 50 amp is actually two separate 50s for total of 100?
Exactly. A 30 amp service has a single 120 vac hot leg protected by a single pole 30 amp breaker.

A 50 amp service has two hot legs protected by a 2 pole linked 50 amp circuit breaker. Each leg measures 120 vac referenced to neutral. But it is 240 vac measured one hot leg to the other. Everything in the trailer is connected to one 120 vac leg or the other 120 vac hot leg.

A 50/30 adapter simply connects both trailer hot legs to the single hot leg in a 30 amp outlet.
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Old 06-25-2018, 12:28 PM   #23
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That is exactly correct. Both hot legs are rated 50 amps, so together you have 100 amps. With the 30 amp system, you only have one 30 amp hot leg, and if you have a 50 amp system, which is two hot legs, connected with a 30 to 50 amp adapter, the single 30 amp leg is split to energize both the hot legs of the 50 amp panel. You are able to use any combination of loads with the 30 amps available, but can’t exceed 30 amps between the two hot legs in the 50 amp rig. On a house that has, say a 100 amp panel, you have two 100 amp legs, and this also applies to larger panels on a house, that you usually get two hotlegs of whatever the panel is rated at.
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Old 06-25-2018, 12:32 PM   #24
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Originally Posted by mtlakejim View Post
So just to be sure I understand this correctly, are you saying that 30amp service is just that but 50 amp is actually two separate 50s for total of 100?
30A service gives you a 30A leg @ 120V = 3600W
50A service gives you two 50A legs at 120V = 6000W each 12000W total
It is 100A total but still called 50A service
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Old 06-25-2018, 01:06 PM   #25
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Yes, to the best of my knowledge...anyone else have thoughts?
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Old 06-25-2018, 01:16 PM   #26
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Got cha

That being the case we are talking about a much larger difference in overall available power between 30 and 50 amp than someone less informed would infer
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Old 06-25-2018, 02:37 PM   #27
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Originally Posted by mtlakejim View Post
So if they had the A/Cs on separate legs would you be able to run both at a 30amp site??
I pull 16 amps on my 15k a/c and 14 amps on my 13.5k a/c so i doubt you could run both a/c's at the same time. With only 30 amps you would have to have both a/c's not exceeding 30 amps together and nothing else running at all. The biggest problem you would have is when just 1 is running then the other kick on. My 30 amps is running amps but when getting a surge when 1 a/c kicks on while the other is running you would exceed the 30 amps. You always have to allow for the fact that your converter/inverter can kick on at any time and would draw more amps. Rule of thumb is 1 a/c = 30 amp service. You might find 1 a/c with 50amp service but never 2 a/c's with 30 amp service on an rv.
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Old 06-25-2018, 06:22 PM   #28
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Hi

The last class I attended disagrees with the 100 amp idea.

A 240 Volt 100 amps stove requires a 100 amp breaker.

The amperages doesn’t multiply the wattage does.

In simple math 50 amps at 120 v = 6,000 watts

50 amps at 240 V = 12,000 watts.

You can produce more “work” at the higher voltage than at the lower voltage without changing the amps.

Here is a picture of the transformer used in the U.S. for a 240V service.
As you see when you add load to the 120V legs as you increase the load on L2 the circuit become a 240V circuit and produces more “Work” for the same amps.

Remember we are working with Alternating Power or AC so when leg 1 is + Leg 2 is – and will only carry 50 amps without tripping the breaker. When leg 1 becomes – the leg 2 become + and can only carry 50 amps without tripping the breaker.

I f you load only one leg to 50 amps the neutral will carry 50 amps but as you add load to the other leg the neutral carries less.

What happens to your trailer when you lose the natural if you are carrying 50 amps on L1 and 20 Amps on L2 the current for the high load flows thru the appliance with the lower ability to carry the load and the little one like your TV becomes a toasted critter.

In my case when I lost the neutral I toasted the Converter and the TV lift the AC’s didn’t sustain any damage.

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Old 06-25-2018, 07:22 PM   #29
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Hi, Mike Sokol from the No~Shock~Zone here. There's so much confusion about 120 or 240 volts for a 50-amp RV service that I just published this article showing how it actually hooks up, and how NOT to do it. https://rvtravel.com/can-i-use-a-wel...-amp-rv-power/


As a number of you have already alluded to, most RVs in the USA don't actually use any 240-volt appliances internally. So while there are two legs of 120-volt power going into your RV from a properly wired pedestal which COULD be wired as 240-volts from leg-to-leg, you can really treat it as a 100-amp/120-volt service for wattage calculations and such.
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Old 06-25-2018, 08:16 PM   #30
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Scottz is right. See link

http://www.myrv.us/electric/
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Old 06-25-2018, 08:35 PM   #31
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I tend to think of the 50 amp RV power as being 100 amp equivalent. You can get 50 amps of 120 vac thru hot leg 1 and/or 50 amps of 120 vac thru hot leg 2. That gives the equivalent of 100 amps of 120 vac (12,000 watts). Or you could even get 50 amps of 240 vac (also 12,000 watts). But there is never more than 50 amps of current ever passing thru any given wire. The center neutral really confuses things unless you really fully understand current flow with two hot legs out of phase.
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Old 06-26-2018, 05:26 AM   #32
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[QUOTE=h2ojocky;1103928]Scottz is right. See link

Hi

Scottz is not correct you add the voltage not the amperage to obtain the 12,000 watts.

120V 50 amps on leg 1 and 120V 50 amps 0n leg 2 only works because the neutral no longer conducts power and the voltage is a total of 240v X 50 amps = 12,000 watts.

See the wiring diagram of the transformer.

The amperage remains at 50.

Here is a modified drawing of the transformer that may help.

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Old 06-27-2018, 02:09 PM   #33
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Originally Posted by mtlakejim View Post
So just to be sure I understand this correctly, are you saying that 30amp service is just that but 50 amp is actually two separate 50s for total of 100?
Yes. 30a is just that. 50a is 50a on 2 legs, so yes, you have 100a available.
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Old 06-27-2018, 02:17 PM   #34
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Yes. 30a is just that. 50a is 50a on 2 legs, so yes, you have 100a available.
It's 6000 watts at a voltage of 120 volts..Instead of 3600 watts at 120 which is the same as most portable rv gensets.... Its' not 220.. its not 12000 watts.. It is 120 volts of 50 amp service.. 25 amps on each leg.. comes to 6000 watts... of equal portable generator or built in power...
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Old 06-27-2018, 02:29 PM   #35
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50/30 adapters

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Mixed in the discussion of campgrounds prohibiting using a 50/30 adapter to connect a 50 amp RV to a park 30 amp outlet, there was a side discussion on whether there was actually 240 vac available in a 50 amp RV. I guess like everything else there is no consistency.

Someone mentioned that their distribution panel did not allow installing a double pole breaker for 240 vac. Mine however does. It is an IOTA IDP-240 120/240 VAC ELECTRICAL DISTRIBUTION PANEL. I suppose the 120/240 means it is configured for either voltage using the appropriate breaker. The breaker spaces alternate between hot 1 and hot 2 just like a home electrical distribution panel. So if I wanted to install a 240 vac clothes dryer (or any other 240 vac device) all I would have to do would be install a 2 pole linked circuit breaker and run the appropriate wire to my dryer closet. Not that I have any reason to do that, but it is possible.
doesn't matter due to most are split into 120 volt systems with two legs so if you use an adapter you're only limited by the amount of amps you use which if you go over will trip the campground breaker at the pole. Unless the campground is doing something shady it shouldn't be a problem!
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Old 06-27-2018, 03:48 PM   #36
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It's 6000 watts at a voltage of 120 volts..Instead of 3600 watts at 120 which is the same as most portable rv gensets.... Its' not 220.. its not 12000 watts.. It is 120 volts of 50 amp service.. 25 amps on each leg.. comes to 6000 watts... of equal portable generator or built in power...
You are not correct. It has been explained multiple times above.

Look at the circuit breaker. It is a two pole circuit breaker, 50 amps on each pole. 50 amps thru hot leg 1 plus 50 amps thru hot leg 2 = up to 100 amps 120 vac capability = up to 12,000 watts.

And it is 240 vac measured hot leg 1 to hot leg 2.

http://www.myrv.us/electric/Pg/50amp_Service.htm
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Old 06-27-2018, 04:15 PM   #37
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50/30 adapters

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Originally Posted by BB_TX View Post
Even though there are two hot legs in the trailer, they are both fed by the single leg from the 30 amp park breaker. A typical 15k A/C pulls 15 +/- amps. You MIGHT run two A/Cs at the same time. But even if you could it would be right on the edge of tripping the 30 amp breaker. And that would mean nothing else at all could be on ac power at the same time.

I can run my 15k A/C on a 20 amp house breaker but it will trip a 15 amp breaker.
The 240V input circuit is divided in your trailer to two 30 amp circuits on two legs, this is by design so the breaker in the trailer trips before you overload the circuit. Using a 50 to 30 adapter only means you have 30amps to work with instead of 50amps. you can play the math anyway you like but bottom line is you have 60amps to work with.
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Old 06-27-2018, 04:32 PM   #38
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The 240V input circuit is divided in your trailer to two 30 amp circuits on two legs, this is by design so the breaker in the trailer trips before you overload the circuit. Using a 50 to 30 adapter only means you have 30amps to work with instead of 50amps. you can play the math anyway you like but bottom line is you have 60amps to work with.
This is really not that difficult. Please read the detailed description in the link below to understand RV 50 amp and 30 amp service.

http://www.myrv.us/electric/
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Old 06-27-2018, 04:41 PM   #39
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Everybody has their own image of what the electrical connections are for the RV, and, remarkably, most of them give the right result, or close to it. The trouble comes in trying to understand someone else's description. Let's try one more and hope it simplifies things.

Imagine the 30 amp park connection as an extension cord plugged into a 120 V 30 amp receptacle. Imagine the RV as two separate plug strips, each with a 50 amp circuit breaker. If I plug one strip into the extension cord, I'll power up anything plugged into it, until I reach a maximum of 30 amps (3600 W). Then the park circuit breaker trips.

If I plug the second strip into the extension cord, too, then I'll also power up anything plugged into that one, but still with a maximum of 30 amp draw until the park breaker trips. If I'm careful, I can get everything in the trailer to work, but maybe not at the same time.

The park's 50 amp connection is like having two extension cords, each on a separate 50 amp 120 V circuit. I can plug each of my plug strips into its own extension cord and draw up to 50 amps (6000 W) on each strip until the circuit breakers in the strips, or the circuit breakers in the park, trip.

Now if it were as simple as that, the park would have to supply an awful lot of current over those 120 V circuits and use very, very large gauge wire. So they use a 240 V circuit instead, which neatly splits into two 120 V circuits because of the power transformer, and their wiring only has to carry half as much current. You can mostly ignore this.

What you can't ignore is that in your 50 amp extension cord, the two neutral wires from the plug strips are combined into one. If that wire comes loose or breaks, you now have one 240 V circuit coming into the RV, not two separate 120 V circuits. That means that across everything plugged into those plug strips, you've got more or less than 120 V, and a lot of those things don't like that, especially motors and electronic circuits. The smoke escapes, and they stop working. Some things that have external power supplies that operate from 120 V to 240 V, like some computers and televisions, probably don't care, fortunately.

So, as someone has already said:

30 amp circuit, 30 amp total.
50 amp circuit, 100 amp total, but don't lose the neutral (get a cheap circuit checker).

And for the purist, you can talk about the power factor and how much current the neutral carries, but who cares?
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Old 06-27-2018, 04:45 PM   #40
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Yes it is there are two 110 feeds
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