My RV is 30 amp. I bought a 50 foot extension cord for it. I'm not sure what gauge it is, probably cheap China crap. Trouble is that it won't carry enough amps to run the AC it will just make the compressor hum. (AC unit is fine) I'm going to buy another cord. Should a 10 gauge cord be robust enough to run the AC with a 50ft length?

220-221..whatever it takes. ..i apologize ahead of time

Where is the other end of that chord plugged into? But yes you should not have much of a voltage drop in a 10wg 50 foot chord if the supply is up to snuff.

Yes you will be fine with #10 AWG for both 120V or 240V for the distance of 50 ft. and for a 30 amp service it will also have a VD of 3%. You should be good to go with #10 AWG.

I might add at the distant of 60 with the same other constants you would want to go with #8 AWG.

Heavy yellow cords are good.
Skinny orange cords are not.

I have it plugged into an outlet that was for my welder. I just converted it to a 30 amp plug and made one of the hots a common in the panel. If I remember correctly, I have 10 gauge 3 wire to the outlet. Probably a good 50 feet on a 50 amp breaker. So the extension cord would be another 50 feet off of that.

10AWG

https://www.amazon.com/Conntek-15360-30A...;psc=1&th=1

10 gauge copper is rated 30 amps.

Compressor is bad??

And you are sure that the start capacitor on the AC units compressor is ok ?

Yup, works fine when connected directly to the outlet or generator. It's defiantly the extension cord.

As was said above, the 10awg is good for 30amps. So you are really running 100’ on that #10. I bet when you were running that welder that #10 was heating up at the breaker though. You are by code pushing the limits on the #10. Having it on the 50amp breaker is a big no-no. I’m wondering what the actual load the ac is drawing though.

Is the air conditioner 120v or 240 v?

Voltage drop,as has been mentioned,is your problem. Electric motors are very voltage sensitive. The start up current can be 3 times the running current. Voltage drop is a function of current and resistance. Smaller wire and greater distance means more resistance equals more voltage drop.

P.s. overrated cheap generators will have smaller wire windings and can have substantial voltage drop at the generator when operated near the rated watts.

Just go to an electric supply house and get a piece of S O cord #8 . Put the plugs on each end. Don't have to worry about it . Plus for what you spend you won't leave it behind. BUT if you keep trying to start your AC on low voltage you will be replacing it soon and often !!!! Cheaper to get the right cord.

Probably what I'm going to do. I can get 50' of that for around $100 and put some 30amp plug ends on it. I'll put regular plug ends on the one I have now and use it for a regular outlet 20 amp for saws and such.

You keep talking Amps, but didn't answer the question of is it 110 or 220 VOLTS?

It's on an RV. 120 volt the entire RV is 30 amp.