A/C work on 15 amp circuit?

Another solution is to use an autoformer.

I'm hoping to get one from Mexico some time in July. I can hardly wait.

joebedford wrote:
If it starts and your cords are heavy enough that they don't warm up, you're good.

I thought I'd better verify my own advice. My RV is at home and is plugged into an exterior 15A GFCI (No, it's NOT on a 20A breaker). I measured 115.5V at the plug. I started my bedroom AC - fan slowed quite a bit when the compressor started. I measured the voltage at the exterior GFCI on the RV: 113.5V.

I guess that 2V drop is acceptable and expected considering I have a 50' 50A cord, then a 50/30 dogbone, then a 25' 30A extension, then a 30/15 adapter.

Someone here will point you toward a plug-in digital AC voltmeter.

Plug it in. Voltage less than 110. Unplug. Lock door. Go Home.

Voltage above 110?

Start AC. Pop breaker? Go home.

Start AC. Struggles to start. Go home.

AC runs OK. Look at meter. 108 volts or above. Marginal but OK

After half hour run hand over yard receptacle, and cord plug

Hot? Unplug. You're done

Cool? Home free

We were in a park where we were on 30 amp, the power dropped because it was so hot and so many were running their A/C. You can hear the A/C straining to run if it's not getting enough - sounds slow and louder than normal.

jaredcb03 wrote:

I checked and the AC unit has a 20amp breaker. The main breaker is 30amp.

I was suggesting that the storage 15A receptacle may be on a 20A circuit (breaker). If other outlets on the circuit are not being used then you'd be on a 20A circuit all by yourself.

SoundGuy wrote:
Don't fall into the Ignorance is Bliss trap by assuming that just because your A/C started up this time on a 15 amp circuit that it always will. Yes, with no extension and using just the trailer's 10 gauge main service cable you will minimize voltage drop under load BUT if the source voltage happens to be lower than it should on any given occasion then you could still have difficulty. Best to measure your source supply each time so you know what you're dealing with rather than just assuming because it was fine the one time you tried it that it will likewise be fine the next time. Nominally the unloaded source should be +/- 120 vac but if you happen to see 110 vac unloaded then that's the time to consider not doing this as imposing your A/C load on an unloaded source that low will easily pull the voltage down under load into the danger zone.

Hopefully that "adapter" you bought isn't a simply puck styel adapter but rather a dogbone style wired with 10 gauge cable that will properly handle the load. ;)

I picked up this thing. https://www.amazon.com/dp/B00192JGA8/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944687722&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B00FYDAP6M&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=TGVN2RASKBS0YZCMTK13

The adapter type with the cable is preferable? They didn't have that when I went in there.

jaredcb03 wrote:
I tried it yesterday and it did work. I didn't need an extension cord either... just the 30-15 amp adapter I picked up at Lowes. A/C ran for about 30 minutes with no problem.

Don't fall into the Ignorance is Bliss trap by assuming that just because your A/C started up this time on a 15 amp circuit that it always will. Yes, with no extension and using just the trailer's 10 gauge main service cable you will minimize voltage drop under load BUT if the source voltage happens to be lower than it should on any given occasion then you could still have difficulty. Best to measure your source supply each time so you know what you're dealing with rather than just assuming because it was fine the one time you tried it that it will likewise be fine the next time. Nominally the unloaded source should be +/- 120 vac but if you happen to see 110 vac unloaded then that's the time to consider not doing this as imposing your A/C load on an unloaded source that low will easily pull the voltage down under load into the danger zone.

Hopefully that "adapter" you bought isn't a simply puck styel adapter but rather a dogbone style wired with 10 gauge cable that will properly handle the load. ;)

Thanks for all the replies.

I tried it yesterday and it did work. I didn't need an extension cord either... just the 30-15 amp adapter I picked up at Lowes. A/C ran for about 30 minutes with no problem.

From a thread like this, sure can tell who understands electrical and who doesn't.
Under normal conditions, on a dedicated circuit, if it doesn't dump the breaker on startup, its not going to dump it a few minutes later. And if it did, what harm was done ??
And listening, is one of the easiest to use voltmeters there ever was. If you hear a good positive......normal compressor start, you can bet your last $ the voltage is good.
There has been times when I had to temporarly run the AC on a 16 ga cord, and knowing I would be on the cutting edge, I would listen,.....(its not hard to hear) at the startup,......if the start up was slow...and sluggish, I would most times abort. Yes, I'm a non electrician,.....w/ common sense.

Heck yeah. i have don it for years.

however the 30 amp cord from the trailer does not require an extension cord.