Originally Posted by turf
i see the adapter and..... well.....
if it is always gonna be in a 15 amp receptacle, why not change the plug? . . .
The purpose of the sideways pin is to prevent you from connecting a 20-amp load into a receptacle where the wiring in the wall is only sized to handle 15 amps. If you know what your loads are and accept responsibility . . .
In my camper, I got rid of the heavy 30-amp direct-wired shoreline cable that powered the DC converter plus the AC circuit breakers. We have no air conditioner or other heavy 120-volt loads to support. In its place I wired in a 20-amp piece of 12/3 rubber "cord" only long enough to reach the "mouse hole," and capped it with a used hospital-grade 15-amp plug I happened to have in my "junk box." This allows me use the converter to charge the battery, and with the right extension cord to optionally use the camper outlets for smaller loads up to 20 total amps.
Originally Posted by JakeC
I don't believe the adapter will give you measurable losses, and it gives you flexibility. If you hard wire it, you may loose some flexibility. That being said, most 20 amp outlets take both plugs. Just pick one
I am picturing "hard wiring" being cutting off the 20-amp plug with the sideways blade, and putting a 15-amp plug on end of the existing 20-amp cable. I would not put a 15-amp cable with smaller wires into the unit without seeing what the actual converter draw was.
1. A 15-amp plug on a 20-amp cable will give more flexibility, not less, as there are may 20-amp circuits with 15-amp receptacles on the end. You can still plug into dual amperage outlets, but can also plug into 15-amp outlets if you watch your loading.
2. I believe it is easier to find a 30-amp/120-volt "RV" to 15-amp adapter (I have one) than it is to find a dual-amperage one that also accepts the 20-amp sideways pins.
3. With an adapter, you may not be able to close a campground pedestal cover. While we had always boondocked, two weeks ago we camped for the first time with power. Closing the cover all the way over the 20-amp outlets 'squished' the 20-amp extension cord where it came out of the back of the straight plug. Having a "hockey puck" adapter to fit the plug into the 30-amp socket would have been worse. I am now looking for a right-angle 15-amp plug for the extension cord. The one at the HD near the campground was $12, but I put off getting it until we got home so there would be more funds for fuel and 'touristy' stuff if needed.
4. There may indeed be losses with an adapter. But worse than lost power is heat. Ever have to jiggle a plug to make a device work? If the contacts lose their springiness, there could be trouble.
For example, imagine you had a slight contact-to-contact resistance of 1/4 ohm on a 120-volt circuit when drawing the full 20 amps. The voltage drop in the adapter is (E=IxR) 20A x 0.25?, or 5 volts. The appliances run OK on 115 volts, but the ' lost' power is from turning the adapter into a 20Ax5V = 100 watt heater, and there could be a fire. Yeeowch!
Turf, I cannot advise you that it is OK for you to do what I have done. You need to read, understand, and be responsible for your own choices . . . .