By Mike Sokol
Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM.
Dear Mike,
What’s the best way to run a power cord to my 50-amp RV out in the driveway that’s 40 feet from my house outlet? The only thing I want to run is the refrigerator, and I really don’t want to drag out my 25-ft., 50-amp shore power cord, plus an extension cord. What would you do? —Jim
Dear Jim,
Here’s how I would do it. Since you can easily get by on 10 amps or so, I would get a nice 12-gauge/50-ft. extension cord rated for 20 amps of current. Yes, you could probably use a lighter/cheaper cord, but to minimize voltage drop I would stick with a 12-gauge cord.
Next, I would get a 15/50-amp dogbone adapter that plugs right in the side of your RV’s shore power inlet. I like the ones with the short whip hanging straight down and the right-angle head. This eliminates any torque moment that would twist a side-mounted plug out of the extension cord socket.
Then plug this into a dedicated GFCI-protected outlet mounted on the side of your house fed by a 20-amp circuit breaker. If you do get a random GFCI trip, then turn off all the circuit breakers in your RV power panel except for the one powering the refrigerator.
There you go, all done. Please let us know how this works. —Mike
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OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 40+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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Good answer Mike,
I just measured the load of the 120 volt heater on my good size Dometic RV absorption refrigerator. It draws about 2.7 amps (325 watts). So a 15 amp circuit will easily power that with some left over for the convertor/charger
Wondering about that 20 amp plug! Would that also start the battery charger going when you plug in. I know when I plug in to my 50 amp, my house battery is being charged, sometimes in bulk. I have my bulk set at 70% & I see 80 amp charging. Dont really know how many amps the charger is actually drawing though.
Dave
If you exceed the amperage 20-amp capability of the 12 gauge extension cord, the 20-amp breaker feeding the home electrical outlet will trip. But even an 80 amp battery charger should only draw 8 amperes or so of current on the 120-volt AC side.
My refridge has a 110 plug and outlet in the back inside the refridgerator area, just pull off the access panel and unplug the ref from the trailer and plug in the cord, The cover obviously wont go back on tight but i’m sure you can sucure it easy enough.
Unless you have a really old refrigerator you have to have 12 volts to operate the fridge so just plugging in the 120 v cord will not operate the fridge. You would also need a battery charger to keep the batteries charged.
Many 5th wheels now have residential refrigerators which use 120-volts AC.
That also works as long as you can easily get to the power plug. Some are more challenging than others.
Mike I hate to be picky but isn’t that a picture of a household 50amp adapter? Sure doesn’t look like my 50amp RV power cord end.
That’s what the 50-amp, twist-lock plug on the side of many RVs looks like. But some RVs will have a hard wired shore power cord, so instead you would need a 15-amp male to 50-amp NFPA 14-50 female outlet dogbone adapter. And there’s other possibilities such as the SmartPlug. Just get what fits…
Also, the reverse works. Run a power cord from motorhome genset to house frig, when you lose house power for extended time.
Thinking of Dorian right now.
If I can get a little technical support from Cummins/Onan, I’ll write an entire article about how to add an extra NEMA 14-50 outlet on a built-in generator in your 5er or Class-A RV. That will allow you to power your entire house from your RV generator in an emergency. But there’s a few tricks involved to make this code compliant and safe. I’ve called and emailed Cummins several times over the last year about this, but so far all I hear is crickets. If you guys will contact Cummins on my behalf, perhaps they’ll finally call me back.
Yes, RV powering house does work very nicely, provided you know what you’re doing powering a house from generator at all. You need to have some means of break-before-make / exclusive feeding to prevent DANGEROUSLY back feeding out to the grid – a house transfer switch/panel or at least handle lockout on breakers. Instead of powering the whole house, easiest for most folks is to live in the more efficient RV and run decent cords to keep-alive loads like freezers.
Several years ago I lived in an area that lost power just about every time a dark cloud passed over so I bought a large generator (6500 watt). It was in my shop and when the power went out I turned off the main circuit breakers and started the generator and we had basic electricity. The big thing was we had hot water to take showers, this was all done after an ice storm took out power lines for 9 days, heating water on a kerosene heater for a sponge bath gets old. Lol