Extension cord/s for Air Conditioner use

[padlin]

Need to live in the trailer during the day for the next week or 2, looking for advise on running the AC and a light or 2 via extension cord/s. I believe the AC is either 10.5 or 11.5 amps.

Have 2 exterior outlets available, one is 15A, the other is 20A, both 120v.

Closest I can get to the 20A is 70'.
Closest to the 15A is 40'.

Camper 30A power cord is 25'.
I have a number of 25' 14awg extensions, anything longer is 16awg.

I have a 30A twist lock to 15A adapter.

The question is what do I need to make this work?

Can I daisy chain one of the 14awg extensions to the campers power cord and run this from the 15A, or do I need to go pick up a 50' 12awg extension and use the 20A?

Here's HD's extension cord selection graph

[rbryan4]

I'd use the 20 amp receptacle Bob, and a 12 gauge cord. The start up amps will probably be in the 13-14 range, and your running amps under 10, so a 15 amp supply would still probably work - but not much left for anything else.


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[thoer]

Bob, since the AC draw is less then 15A, were it me, I'd go with the closer outlet. But once you plug in the inverter will be operating also - do you know what it draws?

[padlin]

I take it you mean the converter. I had a WFCO converter on my old trailer, it drew .2A with nothing running, never checked this one.

I know I can run the AC on 15A, but I've only done it short term, like when folks are coming over to take a look at the trailer.

[rbryan4]

Originally Posted by padlin

I know I can run the AC on 15A, but I've only done it short term, like when folks are coming over to take a look at the trailer.

Yeah, I don't think it's as much how long you run it but what else do you want to run. Since you mentioned "living" in the trailer during the day, I assume you'd want to have some reserve.




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[thoer]

Originally Posted by padlin

I take it you mean the converter. I had a WFCO converter on my old trailer, it drew .2A with nothing running, never checked this one.

I know I can run the AC on 15A, but I've only done it short term, like when folks are coming over to take a look at the trailer.

Opps, yes converter. As long as your total draw is less than 15A, I'd go with the 15, since the longer the extension cord the more voltage drop. But it you get a heavy enough extension cord the voltage drop should be manageable at the longer distance. Or you can hook what you have all up and measure your actual voltage at the end of the cords if you have a voltmeter. Only problem might be overheating the extension cords.

[Brian B-P]

My thoughts:

• I wouldn't consider using any of the 16-ga cords - I assume you're not, either.
• There's no reason you can't daisy-chain cords, although each connection adds a potential problem point, so fewer are better.
• The trailer's cord is 10-ga, so definitely use that for the first 25 feet. If you're thinking of using the 30A twist lock to 15A adapter to use extension cords instead of the trailer cord - no, I wouldn't do that. You do need a TT-30 (campground outlet style) female to 15A (or 20A) male to chain extensions onto the trailer's cable.
• Whether it is worth the extra 30 feet of cord to reach the 20-amp outlet depends on
  • whether or not you think you are likely to exceed 15 amps
  • how much length of cable is in the house from the panel to those outlets
  • what else is on each of those two circuits
• There's no point in going extra distance to the 20-amp outlet if there are any 14 gauge cords in the setup.
• I would definitely use this as an excuse to get a 12-ga extension, even if I were going to the 15 amp outlet... but I already have two of those (with 15-amp connectors, as they all seem to, even though 12 gauge would be enough for 20-amp use).
• Princess Auto has a sale price for you: 50ft 10/3 Single Lit End RV Extension Cord. Although you don't need 10-gauge for safety (since you're bottlenecked at 20 amps or 15 amps anyway), this can be used in campgrounds with poorly placed services, or later at the house if you install a 30-amp outlet for the trailer. Even with this sort of extension, you need the adapter to connect to the outlet.

So

• If I were confident that I would not exceed 15 amps
  I would use the trailer cord plus one extension (or preferably buy a 12-ga) to the 15A outlet, using a TT-30 female to 15A male adapter between cords.
• If I were not confident that I would stay under 15 amps
  I would use the trailer cord plus one 12-ga extension (which would have to be purchased) to the 20A outlet, using a TT-30 female to 15A male adapter between cords.

[gharper]

How about using your RV power cable and a 15 amp male to a 30 amp female plug?Century RV electrical adapter 15 amp male to 30 A female Plug 1 New

[padlin]

Thanks folks, if there is no concern about daisy chaining 2 extensions then I can do either.

I do have one of the little adapters as gharper shows, just need to find it.

Think I'll go see if I can find a 50' 12, it'll work for either. I would feel better being on the 20. Too bad the shade is better near the 15a.

[Brian B-P]

Originally Posted by rbryan4

Yeah, I don't think it's as much how long you run it but what else do you want to run. Since you mentioned "living" in the trailer during the day, I assume you'd want to have some reserve.

I assume that living in the trailer implies using more appliances, so power demand (including peak power demand) would be higher.
Duration can have relevance, too: the longer this setup is used, the greater the chance of forgetting to manage load and exceeding capacity by using something significant while the air conditioner is running (or worse, starting).

[Brian B-P]

Originally Posted by padlin

Thanks folks, if there is no concern about daisy chaining 2 extensions then I can do either.

Just make sure the connection between cords doesn't end up lying in a puddle if it rains.

Originally Posted by padlin

Think I'll go see if I can find a 50' 12, it'll work for either. I would feel better being on the 20. Too bad the shade is better near the 15a.

Makes sense to me. To set expectations, this is probably the bottom end of the price range (different ends, name brands, and other retailers all lead to higher prices): 15 m 12/3 Single End Contractor Grade Extension Cord (of course prices will be lower in the U.S.; for context, Princess Auto is a low-priced chain).

[padlin]

Ended up with this one. Got it at one of the few remaining mom and pop hardware stores. Sometimes convenience overrides price.

https://www.amazon.com/Yellow-Jacket...n%3A4459667011

[fudge_brownie]

Last year at the Mississippi River Rendezvous, Iowa Dave warned me about the adapters that convert the 30 amp plug to a 15 amp. Is that something to be concerned about in this scenario?

[padlin]

Originally Posted by fudge_brownie

Last year at the Mississippi River Rendezvous, Iowa Dave warned me about the adapters that convert the 30 amp plug to a 15 amp. Is that something to be concerned about in this scenario?

You didn't say what the issue was, but guessing it could melt if you went much over 15a. I can check the temp of the connector with the AC running for a while and see if it gets hot. Really shouldn't be pulling anything over 15. Thanks for the heads up.

[C&G in FL]

Bob, I am a bit concerned with what you are proposing. The distances you have mentioned are somewhat long. 30amp RV cords are 10 gauge because they are 25-30 feet long. If they were longer, they would be heavier. I think you mentioned 70 feet. Over that distance you will have voltage drop. I would strongly advise you to consult a licensed electrician. Even 70 feet on a 30 amp circuit would be better wired with 8 gauge wire rather than 10 gauge. There are charts on the net that indicate what sized wire should be used for given amperage and given distances.

[cpaharley2008]

Worse comes to worse his EMS should cut in if the voltage gets damaging low.

[Jim Bennett]

Originally Posted by fudge_brownie

Last year at the Mississippi River Rendezvous, Iowa Dave warned me about the adapters that convert the 30 amp plug to a 15 amp. Is that something to be concerned about in this scenario?

There is a bit of concern if you were connecting a 30A supply with a cord rated at 15A, as the cord would be the weak link, and not the breaker which is supposed to provide protection.

If Bob is using cords rated for 20A which the circuit is fused at, then there is no problem. Any draw too high would not harm the cord, but instead trip the breaker.

[Brian B-P]

Originally Posted by Jim Bennett

There is a bit of concern if you were connecting a 30A supply with a cord rated at 15A, as the cord would be the weak link, and not the breaker which is supposed to provide protection.

If Bob is using cords rated for 20A which the circuit is fused at, then there is no problem. Any draw too high would not harm the cord, but instead trip the breaker.

I agree... although if one used a light cord (less than 12 gauge) in a 20-amp outlet, then the cord could be overloaded without tripping the breaker. Knowing that the trailer has a 30-amp breaker, I would be reluctant to use a 14-gauge cord to a 20-amp outlet. Bob is set because he has a 12-gauge cord.

[Brian B-P]

Originally Posted by C&G in FL

Bob, I am a bit concerned with what you are proposing. The distances you have mentioned are somewhat long. 30amp RV cords are 10 gauge because they are 25-30 feet long. If they were longer, they would be heavier. I think you mentioned 70 feet. Over that distance you will have voltage drop. I would strongly advise you to consult a licensed electrician. Even 70 feet on a 30 amp circuit would be better wired with 8 gauge wire rather than 10 gauge. There are charts on the net that indicate what sized wire should be used for given amperage and given distances.

I agree that this is a valid concern, but I think that 30 amp RV cords are 10 gauge because they carry 30 amps (over any distance), not because they are 25-30 feet long; longer 30-amp RV cords (such as the one I linked earlier, at 50 feet) are still 10 gauge. The wiring through the house can be much longer than 30 feet, and my guess is that the wire sizes are still 14 ga for 15A, 12 ga for 20A, and 10 ga for 30 amps.

There are 8 gauge RV cords, but they are rated for 50 amp service.

Safe current-carrying capacity and adequate gauge to produce acceptable voltage loss are separate (although related because the both involve resistance) issues. If the distance is long enough, keeping voltage loss down may call for larger gauge than required for safe current capacity. So yes, a 10-ga extension would be even better, but I haven't run the numbers to see the difference would be of any significance. In Bob's scenario, I would use the 12-ga extension, and perhaps check the voltage with the air conditioner running.

One more twist: don't coil up any extra cord length in a pile. At high current, it can overheat that way - ratings assume that the cord is laying in an open area by itself, not piled up with more hot cable.