30amp coach / generator

[jlyon69]

Generally speaking, do your average 30A MHs utilize any of the extra amps available/supplied by a 50A generator? Perhaps the better question is can they be setup to?

I know my genny has a 30A and 20A breaker. I don't have an ATS. I'm figuring the coach is running off that 30A breaker and the 20A is doing nothing. I've "heard" that some setups have wired the 20A circuit to the rear AC, so one can use both ACs with the generator running. I can't get this confirmed, but sounds doable. I am assuming my genny has a 30A and a 20A line-out.

The spec sheet for my rig says I have an "Intellitec EMS - Run 2 A/C on 30A service". I've only been able to do this once and only for a short period.... haven't tried it a lot though. When I did see both running at the same time, the EMS amp meter was right at 30A. So it looks to me the EMS will just alternate them rather than run both full time. It doesn't make much sense to run both if you can't even turn a light on

Anyway, I'm just curious about the 20A side of these generators to build my knowledge base up a bit.

[Dave78Chief]

Most mfg's used the 30 amp side to feed the main RV service (Normal 110VAC loads (recepticles, microwave, front AC, etc.), Converter, & fridge AC mode). They use the 20 amp breaker to just feed the rear AC. This approach was based on each AC requiring 15 amps. They typically installed a Front/Rear AC switch which, when hooked to 30 amp shore power (generator OFF), allowed you to either select the front or rear AC. Some people replaced the AC select switch with a special auto transfer switch that allowed the front and rear ACs to cycle (7 minutes front / 5 minutes rear). Some Mfg's, like yours installed a EMS system that allowed you to run both ACs of of 30 amp shore power. This system however, restricts operation of other devices in order to keep the total current draw within the 30 amp shore power limit. Even those though, when using generator, would still use the 20 amp for the rear AC and the 30 amp for the remaining coach service. In the 70's/80's some would share the 20 amp circuit between the microwave and rear AC.

Dave

[wa8yxm]

If your 30 amp RV has 2 air conditioners, and a 50 amp generator then the generator has both a 30 and a 20 amp circuit breaker, Now, sometimes they goof. but the 20 amp breaker feeds the rear A/C via the transfer switch rather than the main breaker box. So with the gen-set operating you can run BOTH air conditioners just like you had a 50 amp rig.. That is Generally... I have to assume (Having spent some quality time in a used RV recently) That not all of them are wired properly. (That one sure was not,,, thankfully I, not being paid, get to pick my repair jobs)

[jlyon69]

Much appreciated Dave. I just now found a manual for my rig. It says there is transfer switch for the genny for the rear AC....but not much else. ... After I sleep on this on this....I'm sure I'll have more questions tomorrow.

[HotMech]

Try not to get bogged down in the 30A 50A confusion.
A coach with 30A service, has just that, On leg of service from a 30A circuit.
The Genset, (most have the Onan Emerald 5500 Marquis), has two circuits, "in phase", making 120vac. One circuit with a 30 amp breaker, and one circuit with a 20 amp breaker. (This is the most common setup for gas rigs, disregard this info if you have a diesel model, like the 7000, or 8000 Quiet Diesel, as they are a lot different) The ratings of the breakers are only that, ratings.
If you do the math, the 5500 Onan, has only 45A total output (5500w/120v= 45.83a)
and believe me, it won't run long at full tilt without tripping a breaker.
The 30A circuit is wired to the main power for the coach, which runs all the coach circuits and the Front AC, most likely through a transfer switch. In that transfer switch is a set of dry contacts, that switch the rear ac to the 20A circuit when on gen power, otherwise it is run by the 30A sevice cable. While not all coaches are set up this way, most of the newer gas rigs are. Some of the older coaches had an Onan 6000, and I've seen some with switches in the closet to adjust for AC and gen or shore power, as well.

A coach with 50A service, is a horse of a totally different color.
50A service on a Motorhome is like 50A service in a house.
Two legs of 50A service providing 240vac available, with a neutral to give the needed 120vac.
So, if you were to install a second 30A service to your 30A coach, (providing it was out of phase with the first one)
you would have a 30A two circuit system, now capable of 240vac, with a neutral for 120vac. You would then have 60A available at 120vac all the while, still short some 40A of the avalible power on a 50A coach at 120vac. All very confusing, I know, but true. to put it simply, a 30A coach has 30A of available power at 120vac. A 50A coach has 100A of availble power at 120vac.
The numbers seem a bit lopsided, but that's the way it works.
K.

By The Way; I never had any trouble running both AC units, converter, and tv, in my coach, on a 30A campground service, before I converted it to 50A.

[Wizard]

On my Winnebago that came with a 30 amp service, all components was rated for 50 amp. The main breaker panel had a jumper to connect the two bus bars so everything could be fed from a single 30 amp. The #2 compressor was wired directly to 20 amp on the generator.

The only thing required to change mine was, new main breaker for panel (20-50-50-20 amp), new #2 compressor breaker (20 amp), new power cord ( 50a, 4 wire), new wire from transfer switch to breaker panel ( #6, 4 wire ), and some minor rewiring, including removing the buss jumper in the distribution panel.

What was Winnebago thinking, my coach has basement air with two compressors, electric water heater, 2300 watt microwave and washer dryer. No way was 30 amp enough. When on 50 amp service now, I can run everything at once.

Don't know if yours can be changed without looking at your drawings. Been an electrician all my life, so was not a big job for me and would be glad to help if I can.

[jlyon69]

After finding an owners manual on-line last night, I gave it a good read this morning.

I attached a PDF of the excerpt on this subject from the manual. So I'm totally clear now on what I have and how it works. This was my last item on my quest to learn and know how everything works in my coach. I think I wore out 2 multi-meters analyzing and testing my systems

Recently installed a solar panel and physically damaged my BCC control board. So I replaced it and while doing that I also replaced the interconnect solenoid and battery disconnect switch....now I got some spares. I was going to install an inverter when I ordered my LED/LCD TVs, but they turned out to be 12VDC. Got rid of the Magnatek and replaced with a 9200 Series PD and threw on a Trik-L-Start.

I just ordered a TriMetric Battery System | Bogart Engineering Model 2025-RV. The install instructions look pretty straight forward, but I may need some help there. I would like to put it in the hallway with all the other controls/readouts but, I don't think I'll be able to access it because of the basement...Looks like all the existing wires are coming from the ceiling. Looks like the easy option is next to the steps as it's right over the BCC. Any insights or thoughts?

Thanks guys for the good info on the genny, much appreciated!

[Dave78Chief]

Yep, even though you only have 30 amp service, the EMS will allow you to run the rear AC (while front AC is running) as long as the overall amperage rate remains below a given set point. In the RV world, that is typically an exception rather than the rule. Very few coachs are designed like that.

The Trimetric control unit can be placed a fairly long way fro mthe shunt. Shunt though has to be close to the battery on the negative lead. The long lead capabilty gives you some fleaxability for placement. I hope you relaized the shunt (100 or 500 amp) and cable have to be ordered seperate from the meter.

Dave

[jlyon69]

Quote:

Originally Posted by Dave78Chief The Trimetric control unit can be placed a fairly long way from the shunt. Shunt though has to be close to the battery on the negative lead. The long lead capabilty gives you some fleaxability for placement. I hope you relaized the shunt (100 or 500 amp) and cable have to be ordered seperate from the meter. Dave

Yep,I got it from Backwoods Solar, they include all the below:

A 500 amp shunt
2/0 lug cable to connect battery to the shunt
Terminal lug to attach your charge and load wires to the shunt,
Surface wall mount box for the meter head
25 feet (or specify your length) of 4 conductor cable with 3 amp fuse for connecting meter to shunt and power.

Thanks,

John...

[zzjea]

I have a Dolphin '98 5350 and it is probably very similar to yours.

I am pretty sure your setup is: genset (30a circuit to coach, and 20a to rear AC) and when 30a shore cord is plugged into socket in elec. bay, you will have 50a and able to run both ac's and other stuff too.

When you are on shore power, the 30a cord is plugged into shore socket and all you have is 30a everywhere. If you need both ac's you probably won't have enough amps so you could run the front on cool and the rear on fan. You probably have a single ducted system which means both ac's are pushing air and it will add to the cooling.

I added a 20a cord to the ATS in the elec. bay that will run the rear ac off the 20a shore socket on most poles while still running the 30a cord to the 30a socket on the same pole. This gives my coach the equivalent of ~50a to the coach in the summer. Works great. If interested, I can give you more info and how you could make one.

I also added a stand alone circuit under my slide where I can plug the 20a cord into in the winter (cold) months and run an elec. heater separate from the 30a coach circuits. This circuit feeds only one outlet near the center of the coach where a heater can be positioned in the hallway or front or bath. Thus ~50a for winter camping.

I also added a 1350w inverter and another ATS for the front coach circuits so I could run tv, dvd, satellite, etc. when boondocking or when shore power fails. This was more for the fun of doing it just in case it's ever needed. We used to drycamp when near the wilderness areas of Colorado, but have not been there for a couple of years. If/when we go back, I'm ready.

Happy trails.

John

[tylerdmoore]

Quote:

Originally Posted by HotMech Try not to get bogged down in the 30A 50A confusion. A coach with 30A service, has just that, On leg of service from a 30A circuit. The Genset, (most have the Onan Emerald 5500 Marquis), has two circuits, "in phase", making 120vac. One circuit with a 30 amp breaker, and one circuit with a 20 amp breaker. (This is the most common setup for gas rigs, disregard this info if you have a diesel model, like the 7000, or 8000 Quiet Diesel, as they are a lot different) The ratings of the breakers are only that, ratings. If you do the math, the 5500 Onan, has only 45A total output (5500w/120v= 45.83a) and believe me, it won't run long at full tilt without tripping a breaker. The 30A circuit is wired to the main power for the coach, which runs all the coach circuits and the Front AC, most likely through a transfer switch. In that transfer switch is a set of dry contacts, that switch the rear ac to the 20A circuit when on gen power, otherwise it is run by the 30A sevice cable. While not all coaches are set up this way, most of the newer gas rigs are. Some of the older coaches had an Onan 6000, and I've seen some with switches in the closet to adjust for AC and gen or shore power, as well. A coach with 50A service, is a horse of a totally different color. 50A service on a Motorhome is like 50A service in a house. Two legs of 50A service providing 240vac available, with a neutral to give the needed 120vac. So, if you were to install a second 30A service to your 30A coach, (providing it was out of phase with the first one) you would have a 30A two circuit system, now capable of 240vac, with a neutral for 120vac. You would then have 60A available at 120vac all the while, still short some 40A of the avalible power on a 50A coach at 120vac. All very confusing, I know, but true. to put it simply, a 30A coach has 30A of available power at 120vac. A 50A coach has 100A of availble power at 120vac. The numbers seem a bit lopsided, but that's the way it works. K. By The Way; I never had any trouble running both AC units, converter, and tv, in my coach, on a 30A campground service, before I converted it to 50A.

Ohhh, for Pete's sake! Come on guys, now I have a headache....maybe a Bourbon and Coke will fix it

Soooooo much to learn and so little time...

[Dave78Chief]

jlyon69,
One of the things to know about many EMS units is that they can control both 110VAC and 12VDC circuits. I do not know exactly what components are controlled on you coach but typically fridge and water heater (electric element) are controled under 110VAC and 12VDC control voltage is used to control things like rear AC shedding. Remove the 12VDC from the rear AC termostat and the AC will shut down. National RV was not the only mfg to do this sort of thing. Some Winnebago coaches and other higher end coaches do this also.

Dave

[jlyon69]

Quote:

Originally Posted by Wizard On my Winnebago that came with a 30 amp service, all components was rated for 50 amp. The main breaker panel had a jumper to connect the two bus bars so everything could be fed from a single 30 amp. The #2 compressor was wired directly to 20 amp on the generator. The only thing required to change mine was, new main breaker for panel (20-50-50-20 amp), new #2 compressor breaker (20 amp), new power cord ( 50a, 4 wire), new wire from transfer switch to breaker panel ( #6, 4 wire ), and some minor rewiring, including removing the buss jumper in the distribution panel. What was Winnebago thinking, my coach has basement air with two compressors, electric water heater, 2300 watt microwave and washer dryer. No way was 30 amp enough. When on 50 amp service now, I can run everything at once. Don't know if yours can be changed without looking at your drawings. Been an electrician all my life, so was not a big job for me and would be glad to help if I can.

Appreciate it Jerry. I have had thoughts about someday updating to 50A, but at this juncture, I really don't have the need. Of course all we have done with it so far is, bring it home from Florida last Apr after trading our old Class C. Our Class C was just an experiment to see if we would like RVing. Now that we have room, we're enjoying it more and more.

[jlyon69]

Quote:

Originally Posted by zzjea I have a Dolphin '98 5350 and it is probably very similar to yours. I am pretty sure your setup is: genset (30a circuit to coach, and 20a to rear AC) and when 30a shore cord is plugged into socket in elec. bay, you will have 50a and able to run both ac's and other stuff too. When you are on shore power, the 30a cord is plugged into shore socket and all you have is 30a everywhere. If you need both ac's you probably won't have enough amps so you could run the front on cool and the rear on fan. You probably have a single ducted system which means both ac's are pushing air and it will add to the cooling.

Yep, you hit the nail on the head John.

Quote:

I added a 20a cord to the ATS in the elec. bay that will run the rear ac off the 20a shore socket on most poles while still running the 30a cord to the 30a socket on the same pole. This gives my coach the equivalent of ~50a to the coach in the summer. Works great. If interested, I can give you more info and how you could make one.

It's been so darned cold here, I haven't been out to really study how everything comes together. But yes, absolutely. My thoughts have been pointing towards at least being able to utilize the genny's extra 20A when plugged into shore power. My thought being on those rare occasions when it's blistering hot, I could run both ACs on full tilt (if necessary or at least for 20 mins or so to get the inside cooled down) and still have power for necessities.
But I like your idea better. You didn't mention if you had an EMS system, but I assume this has to be done so the EMS doesn't have control over that extra 20A.

Quote:

I also added a stand alone circuit under my slide where I can plug the 20a cord into in the winter (cold) months and run an elec. heater separate from the 30a coach circuits. This circuit feeds only one outlet near the center of the coach where a heater can be positioned in the hallway or front or bath. Thus ~50a for winter camping.

Our thought patterns are much alike One of my projects for next spring (Heading to Fla in Feb, come back Apr) was to put an outlet in the water/elec bay for a trouble light or small space heater....just in case. So far we've always been fine with 1 space heater off the 30A...but I like the way you think It's certainly another "just in case" project that I'm always for!

Quote:

I also added a 1350w inverter and another ATS for the front coach circuits so I could run tv, dvd, satellite, etc. when boondocking or when shore power fails. This was more for the fun of doing it just in case it's ever needed. We used to drycamp when near the wilderness areas of Colorado, but have not been there for a couple of years. If/when we go back, I'm ready.

This was also on my short list for upgrades. So far, our dry camping has pretty much been limited to one nighters in rest areas or truck stops while traveling. The DW needs her CPAP each night and we always watch TV in the evening. In our old Class C (1 12v deep cycle), we had to run the genny every night while on the road After we got home last Apr with the new (to us) rig, I went to work. Got her a 12VDC power plug and wired a 12V line from a bedroom sconce light up into the cabinet above our bed. Now I had to deal with the TVs. While checking out inverters, I ordered 2 LED/LCD TVs. They turned out to be 12VDC. I've already wired the front to the antenna booster circuit, works like a charm. In the bedroom is where I've hit a stumbling block.

I can't image there is a 12V line anywhere near the rear TV. If this is true, I'm either going to have to somehow get one there in some obscure way, or get an inverter, which would be a large expense and a lot of hassle for 1 TV. Finding a 12V line or getting one there is more NRV specific, so I will continue this there. The DW and I had a long talk about dry camping last night, seems when we go to FL next month, she would rather boondock it more than hit campgrounds and I agree, so an inverter may be in the picture next year anyway

Thanks much John!

John...