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Old 04-03-2019, 09:54 PM   #1
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30 Amp and AC use with 50 Amp RV

I have a 50 amp RV (5th wheel) and have a question about ac use. I seem to remember that if I’m at a 30 amp campground and use a 50 to 30 amp adapter that I can only use the ac in the living room (15kw) but not the bedroom. I seem to remember that the thermostat will not even allow me to select zone 2 (bedroom).

I know I could not run both at the same time but I don’t know how the the RV would know what the input power is and disable the bedroom ac.

Am I just not rembrring this right or is the front ac not even selectable when on 30 amps?

The reason I ask is I’m looking at a generator that will run the bedroom ac but not the main ac. Can I select which ac to run while using 30 amp?
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Old 04-03-2019, 10:11 PM   #2
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I think you can run what you want.

We have a 2018 Hathaway.

50 amps is two 50’s or 100 amps. 30 is 30 amps. Our ems indicates sometimes we draw over 30. Sometimes 35.

You have to manage your rv usage. We run two ac’s all the time on 30 amp service. If necessary you can run the rear during the day and front at night.

We wait until the converter settles down first. Not max charge. Check your meter. Turn off the electric water heater. We have a gas/electric fridge.

Then you can run two ac’s. The DW sets the two units to different temps to prevent both starting simultaneously. Very careful on first start up. We turn the front off. Then on after 10 minutes.

We also try to stay in state parks with trees. Need less ac. Many have only 30 amp.

The DW even runs the washer/dryer.

Got to plan.
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Old 04-03-2019, 10:31 PM   #3
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I think you can run what you want.

We have a 2018 Hathaway.

50 amps is two 50’s or 100 amps. 30 is 30 amps. Our ems indicates sometimes we draw over 30. Sometimes 35.

You have to manage your rv usage. We run two ac’s all the time on 30 amp service. If necessary you can run the rear during the day and front at night.

We wait until the converter settles down first. Not max charge. Check your meter. Turn off the electric water heater. We have a gas/electric fridge.

Then you can run two ac’s. The DW sets the two units to different temps to prevent both starting simultaneously. Very careful on first start up. We turn the front off. Then on after 10 minutes.

We also try to stay in state parks with trees. Need less ac. Many have only 30 amp.

The DW even runs the washer/dryer.

Got to plan.
We have a 2016 Cedar Creek Silverback. I beloeve the 30 amp to 50 amp adapter ties the the two 50 amp legs together to the 30 amps.

What you say makes sense but I seem to remember when I have been at 30 amp campgrounds my domestic thermostat doe not allow me to go do anything with zone 2. I may just be mistaken...
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Old 04-03-2019, 10:49 PM   #4
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Not sure what thermostat you have but our RVcomfort thermostat will allow you to run either one. At first I couldn't get to work that way, took some trial and error but finally got it to work properly. Now when on 30 amp I run the bedroom air during the day and the living area air at night just to stay away from the noise from the units.
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Old 04-04-2019, 02:13 AM   #5
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Originally Posted by dalford View Post
We have a 2016 Cedar Creek Silverback. I beloeve the 30 amp to 50 amp adapter ties the the two 50 amp legs together to the 30 amps.

What you say makes sense but I seem to remember when I have been at 30 amp campgrounds my domestic thermostat doe not allow me to go do anything with zone 2. I may just be mistaken...
I really think your mistaken or your 30 to 50 adapter is shot.

Do the Cedar Creeks come with a Power Management System?
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Old 04-04-2019, 04:01 AM   #6
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I would doubt that any coach is going to bar you from using both of your a/c units just because you are 'only' on 30amp service - it's still 120v power coming into your rig, and that's what any a/c unit uses - it's thermostat only uses 12v power.

Some EMS(electrical management systems) could be designed to limit the usage of more than one roof air unit while on less than 50amp service, but it's doubtful it would completely remove one from usage - maybe not both at the same time, but YOU would control which unit you want to use.
EMS's are designed to 'shed' certain devices or appliances when the total amps approaches the 'limit' of your available service. It usually, though, doesn't 'automatically' know how 'much' amps you are limited to, without your direct input, only that you are not on 50amp service, which is TWO legs of power. You would have to tell it that you are then on 30amp or 20amp or 15amp, etc.

Most of us with 50amp coaches don't have any EMS system to limit us. When we are using an adapter to plug into 'less than' 50amp service, it's completely up to us to decide 'what' devices and appliances we want to use. Our coaches don't have any way to limit our usage, but using too much at the same time can TRIP breaker(s)...usually the breaker to the outlet you are plugged into.

I don't think you have any problem turning on both a/c units, no matter what 'size' amperage service you are plugged into. What you want to do, though, is not turn them on at exactly the same time.
Most roof a/c units are 13.5 or 15kw sized....either one is less than 15amps when it is fully up to speed. Both of these together are certainly less than 30amps of power.

What you may find, though, is that some 30amp breakers can be 'weak' from overusage by so many campers using the site. The breaker will then 'trip' much more quickly than it should, sometimes leading the owner to believe that they are using too much power.... the reality is that a new replacement breaker may easily solve the problem. It has for us on several occasions.

The other problem, when on 30amp or less service, is that some owners forget that some 'silent' power usage can be going on behind the scenes, such as the Battery Charger and the Electric Water Heater, etc. These devices and appliances, if on, immediately start using a LOT of amps when you plug in. If you have these running while also trying to use multiple air conditioners, you may find yourself quickly tripping breakers.

When on 'less than' 50amp service, you have to understand and manage your electrical draws, ESPECIALLY in either very HOT months, or very COLD months, as both Air Conditioning and Heating are primary users of a LOT of power.
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Old 04-04-2019, 06:54 AM   #7
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^^^^^
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Old 04-04-2019, 07:11 AM   #8
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We have a 2016 Cedar Creek Silverback. I beloeve the 30 amp to 50 amp adapter ties the the two 50 amp legs together to the 30 amps.

What you say makes sense but I seem to remember when I have been at 30 amp campgrounds my domestic thermostat doe not allow me to go do anything with zone 2. I may just be mistaken...
A 30 to 50 adaptor takes the 30 amp leg of the PED and applies it to both the 50 amp legs of your power cord. You get only 120 volts of electricity shared across Both legs of the 50 amp service but you only get 30 amps because the 30 amps ped will trip over that amount.

A 50 to 30 adaptor works differently. It takes only ONE leg from the Ped and applies it to a 30 amp 120 volt cord. The cord has 50 amps available (To use the famous RV world language) but it only goes as far a the 30 amp main breaker in ones 30 amp service.

Your T-stat has no way of knowing what size service you are plugged into.

30/50 and 50/30 are two different adaptors. The first # designates what you are plugging into.
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Old 04-04-2019, 07:28 AM   #9
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Your breaker panel is in a sense two circuits.

I know some 30 to 50 amp dog bones were made connecting to only one circuit. Mine is correct. Is one side dead?

Our Dometic thermostat it is a constant fight to make operate. We hate it. You likely have the same one. As a new owner I am confident you do not know how to make it work correctly. They are that complex. Both the DW and I are engineers.

Yes, in the past some houseboats and other rvs had systems set up to only allow one unit to operate. I doubt you have that. I think that was a rental thing.

Our systems are simple. You have to be in control. Done on purpose.

We have no issues on 30 amp service. Read my earlier posts.
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Old 04-04-2019, 08:02 AM   #10
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Sorry. Did not notice the 16 rv.

Not new?

We have that Dometic thermostat that has four individual settings for two zones. Way more complicated than necessary. We do not need setbacks on a recreational vehicle. Automatic switching between heat and ac. The damn thing does not have a simple override all settings as a fall back. Standard in the past.

We use our fancy 50 amp ems with the 30 amp plug. Interesting to see the amps on the two,legs.

Hang in there. You will figure it out.
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Old 04-04-2019, 08:34 AM   #11
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Thanks for all the replies. I agree with all of you and I must have had a short between the headphones when I looked at it last time.
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Old 04-04-2019, 08:40 AM   #12
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Sorry. Did not notice the 16 rv.

Not new?

We have that Dometic thermostat that has four individual settings for two zones. Way more complicated than necessary. We do not need setbacks on a recreational vehicle. Automatic switching between heat and ac. The damn thing does not have a simple override all settings as a fall back. Standard in the past.

We use our fancy 50 amp ems with the 30 amp plug. Interesting to see the amps on the two,legs.

Hang in there. You will figure it out.
No, I have the thermostat figured out..lol. I just seem to remember that when I was on 30 amp service that when I pushed the zone button for zone 2 it would not allow me to cycle thru the modes for the zone 2. I must have been mistaken and have ‘assumed’ for what ever reason that was the case and never tried again. Thanks for you help.
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Old 04-04-2019, 07:44 PM   #13
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Dalford:
You actually have this reversed. If you tie both legs of a 50 amp service off of the park pedestal together, you will have a dead short with breaker(s) tripping off & maybe some smoke, ha ha!

However, if you tie both legs of the 50 amp power cord from your RV together, and then plug it into a 30 amp park pedestal, you will have a useable 30 amp service to your RV, however, you will NOT have 240 volts available in your RV. So, if you have a bigger rig with an electric dryer inside your unit, the dryer will NOT have 240 volts. It will have zero volts. But the washer should work. I’ve heard other people on this website say this & they are dead wrong. It’s Dangerous to be giving electrical advice if you aren’t sure what you are talking about.
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Old 04-04-2019, 08:20 PM   #14
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A 30 to 50 adaptor takes the 30 amp leg of the PED and applies it to both the 50 amp legs of your power cord. You get only 120 volts of electricity shared across Both legs of the 50 amp service but you only get 30 amps because the 30 amps ped will trip over that amount.

A 50 to 30 adaptor works differently. It takes only ONE leg from the Ped and applies it to a 30 amp 120 volt cord. The cord has 50 amps available (To use the famous RV world language) but it only goes as far a the 30 amp main breaker in ones 30 amp service.

Your T-stat has no way of knowing what size service you are plugged into.

30/50 and 50/30 are two different adaptors. The first # designates what you are plugging into.
Is that not what I said? When I said a 30 to 50 amp adapter I may have stated both 50 amp legs were connected to the 30 amp leg. That is the same as the 30 amp leg is connected to ‘both’ 50 amp legs. At some point the two 50 amp legs are shorted/connected to the 30 amp leg. 120 volts on each 50 amp leg but only 30 amps total available to be shared by each 50 amp leg. Sorry if I did not state it clearly.

That is why I started questioning why I thought the second air would not work because I knew voltage was there. Short between the headphones...lol.
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Old 04-04-2019, 08:26 PM   #15
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Dalford:
You actually have this reversed. If you tie both legs of a 50 amp service off of the park pedestal together, you will have a dead short with breaker(s) tripping off & maybe some smoke, ha ha!

However, if you tie both legs of the 50 amp power cord from your RV together, and then plug it into a 30 amp park pedestal, you will have a useable 30 amp service to your RV, however, you will NOT have 240 volts available in your RV. So, if you have a bigger rig with an electric dryer inside your unit, the dryer will NOT have 240 volts. It will have zero volts. But the washer should work. I’ve heard other people on this website say this & they are dead wrong. It’s Dangerous to be giving electrical advice if you aren’t sure what you are talking about.
Well I appreciate the insult at the end of your post. Welcome to the forum. I never said anything about a 50 amp service. I only talked about a 30 amp service and a 30 amp to 50 amp adapter. May have been a little confusing in how I said it but what I said was true.

And as far as I know there is no 240 vac used in any RV. Washers/Dryers are all 120 volts.

And last, I did not give any advice. I was asking questions and stating what I believe was the case. Nothing I said was dangerous...
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Old 04-05-2019, 06:54 AM   #16
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It’s that thermostat. Hate that thing.

Woke up in Kentucky a couple of weeks ago as the blessed thing was not heating the rv. It was 25 degrees outside. Took the DW twenty minutes to get the heat on. She is not so pleasant at 3 am.

We have a fireplace and small heater in the bedroom. Not enough at 25 degrees.

Anybody know of a simple two zone 12 volt thermostat?
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Old 04-05-2019, 09:08 PM   #17
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Is that not what I said? When I said a 30 to 50 amp adapter I may have stated both 50 amp legs were connected to the 30 amp leg. That is the same as the 30 amp leg is connected to ‘both’ 50 amp legs. At some point the two 50 amp legs are shorted/connected to the 30 amp leg. 120 volts on each 50 amp leg but only 30 amps total available to be shared by each 50 amp leg. Sorry if I did not state it clearly.

That is why I started questioning why I thought the second air would not work because I knew voltage was there. Short between the headphones...lol.
Well, it appears that your wording was confusing to at least 2 of us in this thread. Sbossrman and myself. It came across as tieing the 50 amp legs at the ped. I was just trying to clear up the confusion of different adapters that I are on this forum all the time. Many here do not know the difference or how they work. You post was a good pleace to get it out.

This from your post #15

And as far as I know there is no 240 vac used in any RV. Washers/Dryers are all 120 volts.

The new Maga Land Yatchts' do in fact use 240 volts for dryers and convection kitchens.
Just trying to clear this up.
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Old 04-05-2019, 09:44 PM   #18
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Well, it appears that your wording was confusing to at least 2 of us in this thread. Sbossrman and myself. It came across as tieing the 50 amp legs at the ped. I was just trying to clear up the confusion of different adapters that I are on this forum all the time. Many here do not know the difference or how they work. You post was a good pleace to get it out.

This from your post #15

And as far as I know there is no 240 vac used in any RV. Washers/Dryers are all 120 volts.

The new Maga Land Yatchts' do in fact use 240 volts for dryers and convection kitchens.
Just trying to clear this up.
Thanks Cavie, I respect your posts and look forward to your knowledge. Sorry my post was confusing.

Ok, make me liar for 1 RV out of thousands...lol...so only 99.9% don’t use 240 vac...but your point well taken.
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