Two AC's with 30 Amp Service ?

[Ponder]

Hello...I am a new RV-er and have a million questions but maybe someone can help with one for now.....

I have 30 amp service and two AC's and the two will not run by generator at the same time....but the manufacturer says the Gen will run both but not with 30 amp service in the coach. I found a post that was very complete 6/2/2012 by ""Chaffkeekid"" showing with Pictures and with great detail how to mod wiring (pretty simple)to run two AC's with 30 Amp service....

Does anyone know if this mod was to run off the Generator or one unit off the Gen and the other off shore pwr?? Not sure.

Many Thanks...Ponder

[tropical36]

Ponder wrote:
Hi Tropical.

Pretty sure I selected the 20 amp circuit...it only goes to the Rear AC...the other circuit powers the front AC and all the rest of the 120 volt outlets. If I run the generator, everything works, and when I unplug the pigtail, the only change in the coach is that the rear AC goes off. I feel that the wire with the pigtail (connected to 3external 120 volts) goes to the Intellitec, as does the 30 amp from shore power go to the intellitec...so at this point, Intellitec sees shore power and does not allow the two AC's to run at the same time. Funny thing...I discovered that the rear AC will not run with the extension cord attached to the pigtail unless shore power is connected or unless the generator is running. I think it's the Intellitec EMU-2 that is contoling this. If I can find the wires coming out of the Intellitec to the rear AC, place a receptacle on the wires from the intellitec, and a plug on the wires to the rear AC...This way Make the split after the Intelletic...Would this make any sense? I split the rear AC circuit about 3 feet from the Generator....which of course is before the Intellitec EMU-2.

Thanks Tropical very much for your help again.......Ponder

I understand what you're saying, but then I have an EMS and mine is split well before it as well. Reason neither will run without the coach itself being energized is because whatever supplies the control circuit for the AC's is off and most likely goes through the EMS as well. Mine also has a plug-in relay that sees and decides if rear AC power is available and then feeds it directly, thereby rendering the rear AC breaker on the inside panel useless and just as it does with the gen set in use. If I'm getting this correctly, you also have a manual transfer sw. inside the coach for selecting the front or rear AC and where I think I'd be looking, cuz for some reason this isn't being by-passed. Do you have the instructions for all the various setups that one might encounter? If not, PM me with an email address and I'll send you what I have.

[Ponder]

Hi Tropical.

Pretty sure I selected the 20 amp circuit...it only goes to the Rear AC...the other circuit powers the front AC and all the rest of the 120 volt outlets. If I run the generator, everything works, and when I unplug the pigtail, the only change in the coach is that the rear AC goes off. I feel that the wire with the pigtail (connected to 3external 120 volts) goes to the Intellitec, as does the 30 amp from shore power go to the intellitec...so at this point, Intellitec sees shore power and does not allow the two AC's to run at the same time. Funny thing...I discovered that the rear AC will not run with the extension cord attached to the pigtail unless shore power is connected or unless the generator is running. I think it's the Intellitec EMU-2 that is contoling this. If I can find the wires coming out of the Intellitec to the rear AC, place a receptacle on the wires from the intellitec, and a plug on the wires to the rear AC...This way Make the split after the Intelletic...Would this make any sense? I split the rear AC circuit about 3 feet from the Generator....which of course is before the Intellitec EMU-2.

Thanks Tropical very much for your help again.......Ponder

[tropical36]

Ponder wrote:
Hello Everyone.....I started this thread months ago but realized I was too new to RV-ing so I spent the summer learning some things and only being able to run one of the two AC's at a time on shore power. Both run at once on the generator, but only one at a time on shore pwr. Have 2000 Rexhall with Gererac with two breakers on the generator, each for 30 amps...although the schematic says should be a 30 and a 20. Also have two switches one for front AC and one for the Back AC Inside the coach. Also have Intelletec EMU-2 with transfer switch etc.

I found the J-box with the two circuits running through it from the Generator and installed the Receptacle and pig tale as discussed earlier in this thread....

With the generator running, both AC's work at once via the two switches inside...unless I unplug the pigtail from the outlet, then the rear AC goes off as you would expect. The front AC continues to run and the RV still has 120 volts at the receptacles. But with the generator off, and shore power connected with the 30 amp cord, and an extension cord from 120 volts at the shore power post to the pigtail plug I installed... can only run one AC at a time no matter what position the two switches are in for the 2 AC's.

I think what I have missed here is that both AC's are controlled at the Intelletec EMU-2 and so I am going to have to modify what I have done with the Receptacle and pigtail I think and move this set up elsewhere in the circuit in order to bypass the Intellitec EMU-2. But I am now over my head trying to figure out where and how in the circuits to do this...

Can anyone offer me some help and advise in doing this in order to work with the Intelletec EMU-2...I have the schematic from the manufacturer if this would help...

Many Thanks...Ponder

Don't know where you split the rear AC circuit, but if it was done properly and a little downrange from the gen set breaker that should be a 20amp, then when connected to an external 20amp source, the rear AC won't know where this separate line voltage is actually coming from
and should by-pass the selector switch as it does when running the gen set. If you're not sure of which is the 20amp, check the wire size, with the smaller being what you're looking for and you should probably change out the breaker while you're at it as well.
If there's any confusion, then try disconnecting at the gen set breaker itself, connect an outlet on the load side of the breaker and a pigtail with plug on the disconnected wires. This pigtail could be short and then use an extension cord for reaching the pedestal. If it works, then neat it up and you should be good to go.

[RayChez]

I have never been able to run both air conditioners/heat pump at a time with 30 amp service. The only way I can do it on my coach is 50 amp shore power or the generator Onan 7500.

[Ponder]

Hello Everyone.....I started this thread months ago but realized I was too new to RV-ing so I spent the summer learning some things and only being able to run one of the two AC's at a time on shore power. Both run at once on the generator, but only one at a time on shore pwr. Have 2000 Rexhall with Gererac with two breakers on the generator, each for 30 amps...although the schematic says should be a 30 and a 20. Also have two switches one for front AC and one for the Back AC Inside the coach. Also have Intelletec EMU-2 with transfer switch etc.

I found the J-box with the two circuits running through it from the Generator and installed the Receptacle and pig tale as discussed earlier in this thread....

With the generator running, both AC's work at once via the two switches inside...unless I unplug the pigtail from the outlet, then the rear AC goes off as you would expect. The front AC continues to run and the RV still has 120 volts at the receptacles. But with the generator off, and shore power connected with the 30 amp cord, and an extension cord from 120 volts at the shore power post to the pigtail plug I installed... can only run one AC at a time no matter what position the two switches are in for the 2 AC's.

I think what I have missed here is that both AC's are controlled at the Intelletec EMU-2 and so I am going to have to modify what I have done with the Receptacle and pigtail I think and move this set up elsewhere in the circuit in order to bypass the Intellitec EMU-2. But I am now over my head trying to figure out where and how in the circuits to do this...

Can anyone offer me some help and advise in doing this in order to work with the Intelletec EMU-2...I have the schematic from the manufacturer if this would help...

Many Thanks...Ponder

[bob_b1]

wa8yxm wrote:

Ponder wrote:
Thanks Bob B for that........

Do you have an equally straight forward way to run both AC units from the generator. (no shore power) The coach has a switch that selects either AC unit but not both?? Thanks..

Ponder

Yes,, Set the Front/Rear switch to Front.

The automatic transfer switch in the coach should then Transfer the rear air conditioner to the 20 amp lead on the generator.

(This assumes a motor home, installed generator and automatic transfer switch)

You may also have to turn the 20 amp breaker on the generator itself back on.

X2

[RayChez]

It all depends on what type of air conditioners you have. Some bigger units like the ones on my coach you can not run two air conditioners very long without tripping the circuit breakers. Mine are combination air/heat pump type air conditioners. But if you have smaller units that will not draw over 30 amps, then it is possible to run both A/C. Amps are like water running through a hose. You can only put so much through it before something has to give.

[wa8yxm]

Ponder wrote:
Thanks Bob B for that........

Do you have an equally straight forward way to run both AC units from the generator. (no shore power) The coach has a switch that selects either AC unit but not both?? Thanks..

Ponder

Yes,, Set the Front/Rear switch to Front.

The automatic transfer switch in the coach should then Transfer the rear air conditioner to the 20 amp lead on the generator.

(This assumes a motor home, installed generator and automatic transfer switch)

You may also have to turn the 20 amp breaker on the generator itself back on.

[tropical36]

Ponder wrote:
Thanks Bob B for that........

Do you have an equally straight forward way to run both AC units from the generator. (no shore power) The coach has a switch that selects either AC unit but not both?? Thanks..

Ponder

If I might jump in here, I suspected that you had a sw. inside the coach. As for being straight forward, it shouldn't make a difference which position its in when running on your gen set, since the auto transfer by-passes this switch or at least it's supposed to and what I meant when I stated in my email that something else could be wrong if you couldn't run both off the gen set at present.

[Bumpyroad]

bob_b wrote:
You are all making this too complicated with the Power Management stuff. The generator has two sets of power lines.

Line 1 goes to the big 30-amp outlet inside the storage area (where you plug in your 30-amp cord).

Line 2 goes directly to the back air conditioner. This is the line that many members here have modified.

Take the Line 2 from the generator and terminate it with a standard 15-amp outlet or the Female end of a cord.

Take the line that comes from the rear air conditioner and terminated it with a Male plug.

Now you can plug the rear A/C into the outlet for the generator OR plug it into an unused outlet at the campground electrical post.

You now have your 30-amp cord to the post which will run the front air and you will have a smaller 15-amp cord running to the post for your rear air.

Simple.

It took me a very hot August weekend in Las Vegas to motivate me enough to add the second cord;)

and this is supposedly less work and complication than just letting your EMS take control?
bumpy :@

[Ponder]

Thanks Bob B for that........

Do you have an equally straight forward way to run both AC units from the generator. (no shore power) The coach has a switch that selects either AC unit but not both?? Thanks..

Ponder

[bob_b1]

You are all making this too complicated with the Power Management stuff. The generator has two sets of power lines.

Line 1 goes to the big 30-amp outlet inside the storage area (where you plug in your 30-amp cord).

Line 2 goes directly to the back air conditioner. This is the line that many members here have modified.

Take the Line 2 from the generator and terminate it with a standard 15-amp outlet or the Female end of a cord.

Take the line that comes from the rear air conditioner and terminated it with a Male plug.

Now you can plug the rear A/C into the outlet for the generator OR plug it into an unused outlet at the campground electrical post.

You now have your 30-amp cord to the post which will run the front air and you will have a smaller 15-amp cord running to the post for your rear air.

Simple.

It took me a very hot August weekend in Las Vegas to motivate me enough to add the second cord;)

[Bumpyroad]

topflite51 wrote:
I am always surprised when someone states for a fact that you cannot run two AC's on a 30 amp system. My 98 Southwind does and does it well. Must be magic. On second thought, its the EMS.

x2
bumpy

[topflite51]

I am always surprised when someone states for a fact that you cannot run two AC's on a 30 amp system. My 98 Southwind does and does it well. Must be magic. On second thought, its the EMS.