15 30 and 50 amp adapting concern's and ?

[Johnny's Journey]

I just pulled down some replies I put on another thread because of my uncertainty about adapting a 50 amp supply cord to a 15 amp outlet. I had mentioned that the OP may have lost one leg of the their supply due to stacking adapters. As it turns out I was wrong after reviewing countless wiring diagrams prior to writing this thread. Now I can accept 30 amp feeding a 50 amp but a 15 amp source feeding a 50 amp is pushing things in my opinion. I mean one would have to know what breakers to shut down so just the 12V DC converter will operate to be safe with out over loading due to accidentally turning on other things like when getting ready the day before a trip. Now for my question. Do RV's have anything that could require a 240V AC supply. And if so a 30 amp to 50 amp adapter would be useless not to mention phasing issues for any thing requiring 240 V AC. All comments welcome so I can be better aware. Thanks

[ctbruce]

I'm no electrician and there are quite a few on here that will chime in. I use a 50 to 30 adapter and a 30 to 15/20 adapter to keep my battery charged. Everything else is off: lights, WH, AC, etc. I do this to start up the fridge also. Nothing else unless I run a fan if I am working inside in the heat. SO far no problems. But I would like to hear from others about this. You can never quit learning.

[chuckster57]

We regularly use a 50 to 15A adaptor at the shop if all we are doing is operating lights and slides and refer if that's on the repair order. Saves having to drag out the big "anaconda" as it's been called.

[Outback 325BH]

Originally Posted by ctbruce

I'm no electrician and there are quite a few on here that will chime in. I use a 50 to 30 adapter and a 30 to 15/20 adapter to keep my battery charged. Everything else is off: lights, WH, AC, etc. I do this to start up the fridge also. Nothing else unless I run a fan if I am working inside in the heat. SO far no problems. But I would like to hear from others about this. You can never quit learning.

The reason all of these dogbones/adapters work is because, even though 50 amp service provides 240 volts to the rig, no 240 devices exist.

Remember, 240 volts is two 120 volt legs. Voltage measured across the two legs is 240. Voltage measured across either leg to neutral is 120. All devices in the camper use one or the other leg (but not both). (240 volt devices use both legs to achieve 240 volts.) Some devices use one leg, other devices use the other. 50 amp service provides two 50 amp legs, which gives you a total of 100 amps when using only 120 volts.

50 amp service is two 50 amp 120 volt legs.
30 amp service is one 30 amp 120 volt leg.

When plugging in your 50 amp camper to a 30 amp pedestal, that one 30 amp leg is connected to both legs in your camper. Total amps are limited to 30, however there is nothing electrically wrong. Voltage measured across the two legs is 0... because it is the same leg from the pedestal. This is why no damage would occur is you did have a 240 volt device (which you don't).

When using a dogbone to plug your 30 amp camper into a 50 amp pedestal, the dogbone simply uses just one of the 120 volt legs. The other leg is not connected to anything.

All dogbone usage is totally safe.

Stepping down further to the 15/20 amp receptacle is fine too. The voltage is all the same (120). The amps provided is simply less.


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[Johnny's Journey]

Originally Posted by ctbruce

I use a 50 to 30 adapter and a 30 to 15/20 adapter to keep my battery charged. Everything else is off: lights, WH, AC, etc. I do this to start up the fridge also. You can never quit learning.

So far so good. We concur.

Originally Posted by chuckster57

We regularly use a 50 to 15A adaptor at the shop if all we are doing is operating lights and slides and refer if that's on the repair order. Saves having to drag out the big "anaconda" as it's been called.

Further comfirmation.

Originally Posted by Outback 325BH

even though 50 amp service provides 240 volts to the rig, no 240 devices exist.

The exact answer I was looking for as to why a single leg of power that becomes bridged within an adapter will have no ill affect unless one throws on all the switch's at once.

[xcntrk]

I plug my 50-amp 5th wheel into a 120v 15-amp receptacle before, and sometimes after, every trip I've ever taken. I plug it in the night before, run the fridge to get the temps down before loading it up, etc. You just can't overload that 15-amp circuit. That means the entire Air Conditioning system should remain OFF (at the thermostat).

Keep in mind the majority of your RV actually runs on 12v DC power with a big inverter that can charge/supply the 12v system, typically in 3 different charge levels with the maximum taking the most amp draw from the 120v source. So your slides, landing gear, lights, furnace, ceiling fans, stove, awnings, are all 12v DC sources.

The only 120v appliances are the Air Conditioner(s), fridge (in AC mode), microwave, TV's, 120v outlets, and of course the inverter. You'd have to look up your inverter specs, but on average most only consume 5~10 amps depending on which charge cycle they're in. If the batteries are run down or ALL 12v appliances are in operation, then the inverter will kick up to maximum draw to keep up with the demand. But even at max draw, there's still sufficient amperage on a 15-amp supply to run the Fridge and even TV's as well. It's those gigantic 15k BTU AC units that suck all the power, with most requiring almost a full 30-amps to start the compressor (this is why you never hear both your AC units start at the exact same time).

[Dave W]

I, too, go 50>15/20 plus an adapter and use a 12 gauge extension from a 20 amp receptacle ~100 feet away. This will operate everything but the a/c including any tools up to a pancake compressor.

[Javi]

Converter...

And y'all is overthinking this stuff

[Johnny's Journey]

Originally Posted by Javi

Converter...

And y'all is overthinking this stuff

"My Mother had me tested"