Question About 30 AMP Shore Power and AC

Kevin, maybe you could clarify something for me. I understand an RV 50 amp service has 2- 120volt sources. I don't understand "one to each side".

My house's electric service is 200 amp. There is a left and right side of the panel. Each side is fed by a separate 120 volt source.

My RV electric service looks like it doesn't have two sides, like my home panel, only one. The panel is fed through a 50 amp breaker. The 50 amp breaker is two halves or separate breakers tied together by a single handle. Each half is fed but a 120 volt wire, one black and the other red.

How does the power in my RV feed two sides if there is only one row?
I think I answered my own question. I just looked up the manual for my PD4500 Power Control Center.

It seems instead of a left and right side, like my home's electrical panel, my RV splits it upper and lower. The 50 amp breaker on the incoming power feed is in the center. There's one AC on the upper half and one AC on the lower half.
 
No since the fan is on the same breaker as the compressor. There is only 1 120v Romex feeding each unit. If anything on one of the two fans would work since they are on separate legs in the breaker panel.
Grumpy, I’ve been wondering about that. When I start the generator the fans come on in the AC’s. Then after 90 seconds the timers activate the power to the AC’s and the compressors start. So, I was thinking it might be on different circuit. But in a 50 amp they would not have that right?
 
Kevin, maybe you could clarify something for me.

How does the power in my RV feed two sides if there is only one row?
In your house, you have two bus bars that have fingers pointing toward the middle alternating. So, L1 is the top two breakers one on each side. Then L2 is next and then they alternate all the way down.
You are correct. In an RV 50 amp, you have a 2 pole circuit breaker in the center of the vertical line of horizontal breakers. The top half of the 50 feeds bus upward and the lower half of the 50 feeds down.
Since there are no 240 volt loads in RV’s like these, the panel needs not be like in your home.
 
My pedestal is at least 100' from the sub panel, and the subpanel is ~ 200 yards from the main supply panel.

The orange wire is direct bury, and was there in 2010. The actual age is unknown. I wonder if the insulation is degraded after all these years.
Now this is very concerning!
What size breaker is in your main panel feeding this sub panel 600’ away? If you have a 30 amp load at the sub panel and it has #10 copper conductor, it will have a 17.6% voltage drop. 120x.176=21.12percent 120-21.12=98.88 volts.
Then you have another 100’ after that!
We may have found out why your AC’s will not run.
Some clarification please.
 
At my home setup, I have a 30a pedestal. It feeds my 50a rv with a 30-50 dog bone. We can run anything in the rv with that setup with the exception that only one ac at a time can be run. It's been used that way for 15 years with not any problems. We rarely run the microwave when at our home.

If we attempt to run both units, the pedestal 30a breaker will trip.
 
Can you tell the people with 50 amps what dogbone you have? It seems the cheap ones do not necessarily power both lines of the 50.
 
Grumpy, I’ve been wondering about that. When I start the generator the fans come on in the AC’s. Then after 90 seconds the timers activate the power to the AC’s and the compressors start. So, I was thinking it might be on different circuit. But in a 50 amp they would not have that right?
If you have the Power Management System that would be the difference.
 
The only possible answer that meets all of the information provided is that there is a Power Management System in place and it realizes that there is not enough voltage\current to run the compressor(s). Likely there is a setting for the Power Management's configuration although I would be cautious with changing any settings without more information.

I base this on the understanding that some Power Management systems only control the compressor and not the fan, and that if there wasn't a power management system, when trying to start the AC(s) that there would be an obvious starting attempt (likely very obvious) for the compressor that isn't occurring. Without some controlling component the compressor would at least attempt to start and from what I have read from the OP, there is no mention that the compressor even tries to start.

There are other things that could be checked and tested, but none of them meet all of the conditions reported so far (more voltage measurements could be of value) other than that there is likely a Power Management System in place and configured to not allow power to the AC compressor(s) under the connection conditions the RV has when the AC compressors will not even "attempt" to start. It is possible to change the settings although more information is needed regarding a Power Management System or confirmation that there isn't one (which I highly suspect there is one). ~CA
 
Last edited:
For the OP, if you can grab a few pictures of your control panels and the area they are located then I may be able to confirm if you have a Power Management System. It may be labeled for you as Power Control, or Power Management, or similar or it could be a part of a larger system. ~CA
 
With the distances given for the sub panel feed and the branch circuit length, unless someone upsized the conductors to 100 ampere rated, the voltage drop would be the issue. Testing voltage at the end with no load would be near original voltage. Put 20 to 30 amps on it, the voltage drop will show up, especially if it was run in #10 copper.
 
Grumpy, I’ve been wondering about that. When I start the generator the fans come on in the AC’s. Then after 90 seconds the timers activate the power to the AC’s and the compressors start. So, I was thinking it might be on different circuit. But in a 50 amp they would not have that right?
After working on my RV this past weekend, I do remember that one AC breaker is above the main 50 amp input, and one AC breaker below.

When I'm on a good 50 amp shore power, or generator power, either AC fans will start immediately, but there's a short delay before the compressor(s) kick in. My Firefly panel has either a fan icon or a snowflake icon.

The first time I had a problem with my AC, at this particular campsite, was a few weeks ago. I thought the AC was running, but it was only the fans.
 
For the OP, if you can grab a few pictures of your control panels and the area they are located then I may be able to confirm if you have a Power Management System. It may be labeled for you as Power Control, or Power Management, or similar or it could be a part of a larger system. ~CA
I'll get some pictures, but it may be a while. I dropped my RV off at the dealership yesterday. It looks very similar to a Progressive Dynamics PD4500, and is located in the foot of the bed.
 
After working on my RV this past weekend, I do remember that one AC breaker is above the main 50 amp input, and one AC breaker below.

When I'm on a good 50 amp shore power, or generator power, either AC fans will start immediately, but there's a short delay before the compressor(s) kick in. My Firefly panel has either a fan icon or a snowflake icon.

The first time I had a problem with my AC, at this particular campsite, was a few weeks ago. I thought the AC was running, but it was only the fans.
Maybe you do have a EMS in that rig. Why not contact Jayco and ask.

 
The only possible answer that meets all of the information provided is that there is a Power Management System in place and it realizes that there is not enough voltage\current to run the compressor(s). Likely there is a setting for the Power Management's configuration although I would be cautious with changing any settings without more information.

I base this on the understanding that some Power Management systems only control the compressor and not the fan, and that if there wasn't a power management system, when trying to start the AC(s) that there would be an obvious starting attempt (likely very obvious) for the compressor that isn't occurring. Without some controlling component the compressor would at least attempt to start and from what I have read from the OP, there is no mention that the compressor even tries to start.

There are other things that could be checked and tested, but none of them meet all of the conditions reported so far (more voltage measurements could be of value) other than that there is likely a Power Management System in place and configured to not allow power to the AC compressor(s) under the connection conditions the RV has when the AC compressors will not even "attempt" to start. It is possible to change the settings although more information is needed regarding a Power Management System or confirmation that there isn't one (which I highly suspect there is one). ~CA
Is there a popular brand of power management system? What would one look like?

When I get my RV back from the dealer, I can look for one.
 
I'll get some pictures, but it may be a while. I dropped my RV off at the dealership yesterday. It looks very similar to a Progressive Dynamics PD4500, and is located in the foot of the bed.
That is the best bet overall. Let the dealership check it all out and before you leave with your RV, be sure to ask about the location and settings for the Power Management System, then if they show it to you, you will know for sure. ~CA
 
Just to recap as I remember things or they become clearer in my mind, both AC's work on generator power or "good" 50 amp shore power.

At my seasonal campsite, I can't get either AC to work. I believe low voltage is the problem. I also have trouble with one slide fully retracting.

What I don't understand is why neither AC will work at my home's 30 amp outlet. That outlet is run with 4 gauge copper. Maybe there's some sort of time delay on an EMS that I need to wait a little longer.
 
Just to recap as I remember things or they become clearer in my mind, both AC's work on generator power or "good" 50 amp shore power.

At my seasonal campsite, I can't get either AC to work. I believe low voltage is the problem. I also have trouble with one slide fully retracting.

What I don't understand is why neither AC will work at my home's 30 amp outlet. That outlet is run with 4 gauge copper. Maybe there's some sort of time delay on an EMS that I need to wait a little longer.
Is this correct? 200 yards from panel to sub panel and 100’ from sub panel to 30A receptacle, and 50’ of cord to the Rv panel?
If so, what is the breaker feeding the sub panel, and what is the wire size. Then what is the breaker and wire size from sub to receptacle?
If you tell me this, I can probably show you the voltage drop happening.
In the park, since you do not know what others have plugged in, it may be that bigger rigs are there and are causing more voltage drop than at other times.
 

New posts

Try RV LIFE Pro Free for 7 Days

  • New Ad-Free experience on this RV LIFE Community.
  • Plan the best RV Safe travel with RV LIFE Trip Wizard.
  • Navigate with our RV Safe GPS mobile app.
  • and much more...
Try RV LIFE Pro Today
Back
Top Bottom