Home plug-in options?

[MFL]

When my 30 amp FW is at home, I have two electrical options. I can plug in close with a 25' 12 ga cord, into a 15 amp circuit.

I also have a 30amp circuit, just for a rarely used air comp. It would require a 50' 12 ga cord to reach.

I have a 30 to 15 amp 6" dogbone, that I use to hookup.

My question is, will I get much more amperage from the further away 30 amp circuit, than the closer 15 amp, since I still need the 30-15 dog bone to hook up?

Will I only get 15 amps no matter what, since the dogbone is reducing to 15 amps?

I would appeciate any help or thoughts.

Jerry

[wa8yxm]

One recommendation if having a professional do the upgrade.

Have him put in a 50 amp outlet.. IF cost is a factor you can use 30 amp wires and breakers (for most "Home" sites this is more than enough power) but have him install a 50 amp outlet.

Two reasons:

1: Odds a professional will mess up a 4-wire 50 amp outlet: Very low (though I've seen it happen.. but this was not an outlet and the only damage was a couple fuses)

2: If you ever upgrade to a 50 amp rig.. No changes need be made.

OH and 3: The dogbone you use to plug in at home ... Can be used in a park with a faulty 30 amp outlet in the box (many of those out there).

[myredracer]

The fact that the electrician installed a 30 amp breaker and used #12 ga. (20 amp rated) wire is not necessarily wrong. For dedicated motor circuits, different rules apply and it is permissible to use a breaker of higher rating than the min. necessary wire size (as with an RV A/C for example). This is because motors have a momentary high inrush current, sometimes in the order of 6 times the full load running current. If a higher rated breaker is not used, the breaker would trip every time the motor tried to start.

This thread gives some relevant info. motor wire & breaker sizes

What I *think* what the electrician did wrong is use a standard duplex receptacle. My experience as an engineer is with the Canadian Electrical Code and I'm not sure what all the current applicable rules are for motor circuits in the NEC. I think a single 20 amp (or possibly 15 amp) receptacle should probably have been used along with a label identifying the recept. as "compressor use only". But you would need to either read the current NEC rules or ask the local inspector. (It's been many years since I've read the NEC alongside the CEC.) The way it sits now, an ordinary 15 amp duplex recept. with a 30 amp breaker is a bad idea.

If you are going to install something new or modify the existing installation for a dedicated power source for an RV, I would highly recommend installing a disconnect switch ahead of the receptacle (30 amp or 15 amp). You should avoid plugging in live because you can end up with pitting on the plug and inside the recept., caused by the inrush current of the converter when it's plugged in, which can lead to overheating and a meltdown or worse. A motor-rated disconnect switch works well because they are designed for higher make/break current.

If you're not going to ever use the A/C, a 15 amp circuit is just fine. It doesn't sound like there is a voltage issue that would warrant using higher gauge wire. If you plan to retain the existing compressor circuit/receptacle for the compressor, I would install a single receptacle (not "duplex") and check the FLA of the compressor motor to see if it should be 15 or 20 amps. It could be that the wire is over-sized as it is now and not an issue.

[AllegroD]

If that 15amp socket is pat of a gang and has other items, like freezer, you might trip the breaker, at times.

[MFL]

Thanks everyone, for your replies. I had a licensed electriction install that setup for my compressor, but surely would not want to have him do my eventual RV 30 amp.

I think I will use his 30 amp breaker and 10 AWG wire to wire to a 30 amp RV box myself, when the time comes.

I think for now, I will just plug in at the 15 amp outlet on the front of my garage, since I will only run the fridge prior to travel. Doug says 15A is all I need, and it will be handier to use.

I would not try to run my 15,000 BTU AC, on the setup I have. I do have to say again, that the compressor plug-in is 121-122 volts on the meter ( no question about it).

Thanks again everyone, for your help!

Jerry

[wa8yxm]

A 30 amp outlet for an air compressor is often 240 volts and if so it will flash fry all your electronics in the RV,, It is not to be used unless you first confirm that it is only 120 volts flat blade to flat blade (The round one is safety ground).

DO NOT try to "Adapt" (though I know of folks who have) since the safety ground is often smaller than the proper NEUTRAL wire,, Bad things can happen.

[time2roll]

MFL wrote:
Is there a heavier dogbone that I could buy, such as 30-30 or 30-20? I have only seen the 30-15.

The 30-15 dogbone is fine. There is no difference in ampacity or conductivity between 5-15 and 5-20 outlets. Puck style adapters seem to heat up more than a dogbone so avoid the puck for high loads.

Yes absolutely replace the 30a breaker with 20 amp or pull #10 wire as you are not in compliance with NEC. 30a & #10 requires a 30a connector.

[pianotuna]

Hi,

I'd be replacing that 30 amp breaker with a 20 amp.

[doughere]

Unless you want to run the AC, 15A will do fine.

Doug

[ChooChooMan74]

I would rewire with 10AWG and get a 10AWG extension from Harbor Freight and cut off the ends and use the ends you need to make it work.

[MFL]

Jim, thanks for the reply. I don't know why he just used 12 AWG. I thought maybe due to the short distance, and the air compressor being just a 2hp small unit.

I have been using this outlet, with the 50' 12 ga extension, thinking this is giving more amps than the outlet on the front of my garage, that is only on a 15 amp breaker, and 14 AWG wiring.

I may eventually do the 30 amp 10 AWG, just for my RV, but just not going to get it done this year. I am somewhat overwhelmed with other priorities, that just never seem to let up.

Jerry

[TucsonJim]

The electrician made an error when he used 12 AWG wire and a duplex outlet for a 30amp circuit. 30 amps requires 10 AWG wire minimum for a 30 amp circuit.

Here are the wiring requirements:

15amp - 14 AWG
20amp - 12 AWG
30amp - 10 AWG

Also, a 30 amp circuit requires a different receptacle compared to your normal 15/20 amp duplex receptacle.

If it were me, I'd connect a new 30amp breaker, 10 AWG wire and dedicated 30amp outlet for the RV, and I'd replace the 12 AWG wire and duplex outlet for the compresser.

[MFL]

The 30 amp circuit is 110/120. It is a 30 amp breaker in my home entrance, that is wired just a short distance to my compressor, with a normal 2 outlet plug in.

The electrician just used a 12 ga wire to the outlet, about 10 feet.

Is there a heavier dogbone that I could buy, such as 30-30 or 30-20? I have only seen the 30-15.

I normally just plug in for charging the battery, and using the fridge on electric, when getting ready to go camping, otherwise I'd consider putting in a proper RV outlet.

Thanks for your reply pianotuna!

Jerry

[pianotuna]

Hi Jerry,

The dogbone won't reduce the amperage--but it is probably rated for 15 amps. If you use it for more than a short time at a 30 amp draw it may melt.

A #12 cord is limited to 20 amps.

Are you certain the 30 amp circuit is 110 volts?

If so, make up a #10 cord and perhaps add a proper 30 amp outlet to the air compressor.