Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: floridarandy on May 28, 2024, 04:06:53 pm
Title: 50 amp question
Post by: floridarandy on May 28, 2024, 04:06:53 pm
First, let me apologize in advance. Any question I ask about electrical will probably be a dumb question. It's one of the things in life. I have never truly understood.
I've attached pictures of the electrical panels in our U270. I had always understood that 50 amp service gave you 50 A on each leg or 100 A total. I'm confused by the fact that what I have always understood was the main panel has 2-50 amp breakers. Somewhere along the way, I had gotten the impression that the even numbered breakers were on one leg, and the odd numbered breakers were on the other. If this is true, and both air conditioners are on the same leg.
But, the second Panel also has a 50 amp breaker, but the only large draw appears to be the microwave.
So my questions are as follows:
1. Why is there a second panel of if there is only really a max of 100 amps when plugged into 50 amp service?
2. When I connect to 30 amp with an adapter are all these circuits in both panels "hot"? And, if so can I manage running all of them, in different combinations so long as their combine draw is 30 amps or less?
Thanks
2. Why is there a second panel
Title: Re: 50 amp question
Post by: wolfe10 on May 28, 2024, 04:18:06 pm
I've attached pictures of the electrical panels in our U270. I had always understood that 50 amp service gave you 50 A on each leg or 100 A total. I'm confused by the fact that what I have always understood was the main panel has 2-50 amp breakers. Somewhere along the way, I had gotten the impression that the even numbered breakers were on one leg, and the odd numbered breakers were on the other. If this is true, and both air conditioners are on the same leg. YOU ARE CORRECT, TWO 50 AMP BREAKERS FOR TOTAL OF 100 AMPS @ 120 VAC. AND, YES, LOADS ARE STAGGERED BETWEEN THE HOTS AS YOU GO DOWN THE BREAKERS.
But, the second Panel also has a 50 amp breaker, but the only large draw appears to be the microwave. THE SECOND PANEL WILL BE FROM THE INVERTER "OUT" AS ONE INPUT AND MAIN BREAKER PANEL AS PRIMARY INPUT.
2. When I connect to 30 amp with an adapter are all these circuits in both panels "hot"? And, if so can I manage running all of them, in different combinations so long as their combine draw is 30 amps or less? CORRECT. INSIDE THE 30 AMP MALE TO 50 AMP FEMALE ADAPTER, THE SINGLE HOT ON THE 30 AMP END IS WIRED TO BOTH HOTS ON THE 50 AMP END. TOTAL OF 30 AMPS @ 120 VAC AVAILABLE.
Thanks
2. Why is there a second panel. SEE ABOVE-- ONLY SUPPLIES THOSE CIRCUITS THAT CAN BE RUN BY THE INVERTER.
Title: Re: 50 amp question
Post by: floridarandy on May 28, 2024, 04:39:39 pm
Brett - forgot the pics. Which circuits in the 100 amp main panel are on each leg?
Title: Re: 50 amp question
Post by: wolfe10 on May 28, 2024, 04:50:02 pm
Which circuits in the 100 amp main panel are on each leg?
As you said, as you go down the breakers, the alternate between L1 and L2.
Your picture #1 is of the "inverter supplied" panel. Pictures #2 and #3 are of the main breaker panel.
Title: Re: 50 amp question
Post by: Gerry Vicha on May 28, 2024, 05:13:55 pm
It is my understanding that most Motorhomes and most Recreational Vehicles which have a 50 amp feed, still only have 120 volt service. The 240/50amp pedestal does have 240 volts. It is split when it feeds into the Motorhome, each 120v leg goes to a different buss bar in the transfer switch, and on into the breaker box. The generator only produces and feeds 120 volts into the transfer switch. The "Load" is split in the breaker box between the two sides (buss bars) of the panel, so as not to overload either feed. None of the breakers are strapped (meaning dual/double Breaker one on each buss bar), to produce 240 volts. I am not an expert in Electricity so this is only MY theory.... ??? ::) ???
Title: Re: 50 amp question
Post by: Michelle on May 28, 2024, 05:30:30 pm
Somewhere along the way, I had gotten the impression that the even numbered breakers were on one leg, and the odd numbered breakers were on the other. If this is true, and both air conditioners are on the same leg.
That was not the case in our 2003 (the even/odd breakdown). Do you have your coach schematics? It will show on drawing A2700.xx which leg each breaker is on. Here is our old one.
Note in our coach, breakers 3, 4, 6, 7, 12, 14 were on leg 1. 8, 9, 10 (and blanks for 11, 16, and 18) were on leg 2.
Also note the 38.4 amps for subpanel on leg 2. Leg 2 of shore power fed the transfer switch for the breakers in the inverter-powered sub-panel. The items in the sub-panel will work on both shore and inverter power. The items in the main panel will not work on inverter power.
Title: Re: 50 amp question
Post by: turbojack on May 28, 2024, 05:54:14 pm
With the 1/2" breakers, 2 are on the same phase. When you have 1" breakers the one above and below are on other phase.
Your AC's are on different phases.
Title: Re: 50 amp question
Post by: craneman on May 28, 2024, 05:59:50 pm
On my '99 the two legs are jumped with a 12 ga. wire at the generator box. Jeff called it a load balance wire. Don't see how they could be on different phases.
Title: Re: 50 amp question
Post by: Elliott on May 28, 2024, 06:20:35 pm
Brett - forgot the pics. Which circuits in the 100 amp main panel are on each leg?
If you can safely kill all power to your coach, just take the cover off the main panel and pull a few of the breakers out. I didn't truly understand how any of that stuff worked until I had to wire up a few 100amp panels on my property. Once you see how the guts work (it's pretty simple) it's much easier to understand.
Title: Re: 50 amp question
Post by: Barry & Cindy on May 28, 2024, 09:33:17 pm
Adding few more comments: Coach electric system has two LEGS. Pedestal should have different PHASES on each LEG, but there is no guarantee campground is always wired correctly, so it could happen that each LEG is from a single PHASE. Generators sometimes (many times) are wired with only one output PHASE that feeds both LEGS. There are advantages and disadvantages when generators are wired with one or two PHASES. Some generators cannot be wired with two phases and can only output 120 volts. Without managing PHASE & AMP awareness, coach neutral white wire can be overloaded above its 50-amp rating.
Title: Re: 50 amp question
Post by: oldguy on May 28, 2024, 09:48:58 pm
Actually it is only one phase and the two outside lines on the plug are 240 and from either outside lines to I think is the middle bottom on is 120
Title: Re: 50 amp question
Post by: wolfe10 on May 29, 2024, 07:59:42 am