Running AC from Generator 150 feet away

[mtnman1000]

I have a TT with a 13,500 BTU Dometic AC and am struggling with finding a good way to power it. My off grid property has an Onan 5.5 KW propane generator for use when the solar system needs charged or additional power is needed. I tried to use a a 100' 10/3 extension cord plugged in before the transfer switch that feeds the house and nothing is drawing power in the house. This resulted in 115 volts when the AC compressor is not on but once it turns on it goes down to 99 volts after a couple of minutes making the fan run slower so I cut it off. There is a bit of additional solid copper from the generator to the outlet I am using of about 30' plus the 30 amp RV plug which is 25' if I remember right.

My question is, is the voltage drop due to not a heavy enough gauge extension cord? If so, I can run some romex under the grass and install an outlet near the camper so what gauge would be recommended. My power draw is 11 amps when the AC is running plus another 2 for misc items.

Thanks in advance.

[mtnman1000]

Thanks a ton for everyone's input, I at least have some direction now.

I am trying to sell my property so have decided not to go with heavier wire and conduit or a transformer but certainly great ideas that would probably fix the issue. I do have a Honda EU3000is but really want this to work so I can run off the 500 gallon propane tank and should be slightly cheaper.

I tested the voltage at the outlet I am using which is about 40 feet from the generator and got 117 with no load and 111 shortly after the AC kicked in. The voltage at the camper was 102 this time but it was much cooler outside. I am going to see what happens if I install an outlet at a splice that is 8 feet from the generator. If this helps enough to make sense I will shorten the extension cord about 15-20 feet which should make the entire circuit about 120 (it's actually close to 175 feet right now). I will also check all connection points.

[MEXICOWANDERER]

WHY YES OF COURSE. SILLY WABBIT...

Ohms law applies differently to different brands of generators. E=I/R is easily swayed. There ought to be a law right (and a rhino dart gun)

[Chum_lee]

Bipeflier wrote:

Dennis12 wrote:
Sounds to me like you have a CHAMPION and don't like the noise. Buy a Honda and sit it right beside your unit.

I nominate this post for the LEAST HELPFUL in the past year!

And I nominate your post as the second LEAST HELPFUL in the past year. (and mine as the third)

It's OK not to like Champion generators as well as any other Brand. It does get things stirred up though.

Chum lee

[Bipeflier]

Dennis12 wrote:
Sounds to me like you have a CHAMPION and don't like the noise. Buy a Honda and sit it right beside your unit.

I nominate this post for the LEAST HELPFUL in the past year!

[greenrvgreen]

As others have said, the OP is getting greater V drop than 100x30awg would suggest. The OP should be able to truck along at the 108V area w/ dips into ~103. Worry-warts will howl, but I have done this for YEARS and not yet shortened the life of the AC, nor have I run out to pay $600 for a Voltage booster to extend the life of my $500 AC.

OP should make sure that the 99v is not a momentary inrush reading. With a quick enough meter one can even catch 85V on a single cycle. Nothing harmful there.

I also want to thank the Champion-hater for bringing his uninformed perspective here where it can shine most clearly. Shinola!

[LittleBill]

Dennis12 wrote:
Sounds to me like you have a CHAMPION and don't like the noise. Buy a Honda and sit it right beside your unit.

Sounds to me like you don't know how to read. Guy has an Onan.

Maybe you should take the hatred down a notch on Champion.

[road-runner]

I missed the part about the Champion generator. I thought I read that the OP has one of the larger Onans that might well be quieter than a Honda.

[Dennis12]

Sounds to me like you have a CHAMPION and don't like the noise. Buy a Honda and sit it right beside your unit.

[valhalla360]

You are basically pushing the limits for voltage drop with 10g wires if you limit it to 5% (fairly typical limit).

If the 150' doesn't include the 30' built in cord or there are additional internal runs from the generator to the plug, a poor quality connection that eats up some voltage or maybe the generator isn't putting out what it should (no load voltage often can appear fine but drops under load.

Suggestions:
- Check all connections to make sure they are clean shiny with no corrosion.
- If possible, move the trailer closer and see if the voltage stays up with just the 30' built in cord. (if not possible, is there something in the house with similar draw you can check to confirm the generator voltage stays up when under a significant load).

If all those check out, it's probably just voltage drop due to the distance.
- If there is excess cord coiled up, can you cut it down? If it's 5-10' probably not worth the trouble but if you can cut 30-50' out, it might make the difference.
- Switch to a heavier gauge cord.
- Consider a voltage booster (aka: autoformer). At 99v, it may still be marginal. Our's gives a 10% boost which still leaves you below 110v.

[MEXICOWANDERER]

Use this as your step down at the rig. Lots of 120/240/480 transformers on eBay. They are easy to connect. Run SEPARATE wires in underground (buried tubing).

Why even put up with a five volt loss? Its silly...

http://www.ebay.com/itm/Acme-3-Kva-1-Phase-Transformer-Pri-240-x-480-Sec-120-x-240-Single-Phase-Used...

[pianotuna]

Big fat wire. Aim for a 1% voltage drop. Move the generator closer.

[2oldman]

I think that's too long for #10. The post above reports 104-108v. I would not be comfortable with that.

[time2roll]

When the A/C was at 99 what was the source voltage? Seems like a larger drop than would be expected. Possibly a loose connection at some point. Extension cord connectors are notorious to cause trouble.

The other issue is why did the power fade with time? Is it source regulation? Connection getting hot and loose?

If this is to be used often I would hardwire #6 copper.

[KD4UPL]

Yes, your wire is too small. I'm kind of surprised because I've run my air conditioner on 125' of 12 gauge extension cord plus the camper's #10 cord and it worked fine. My voltage stayed around 104 - 108 if I remember correctly.
I wouldn't run romex under the grass, it's not rated for outdoor use or wet locations. You would want to run UF cable in that application or better yet, run PVC conduit with individual conductors.
According to Southwire's calculator #10 should be large enough. So, maybe you have some other high resistance wire problem or a generator problem. If you run new wire I would at least go to #6, it's not much more than #8. If you went even bigger to #4 you would see a bigger price jump.

[Bipeflier]

Do your calculations here:Southwire calculator