30 amp to 50amp Adapter

1BryNelson wrote:
I bought 1 of those digial voltmeters; very interesting to watch what appliances take what voltage, especially at start up.

I think you mean current (amps) at startup.

I bought 1 of those digial voltmeters; very interesting to watch what appliances take what voltage, especially at start up.

Larryr wrote:
In reviewing the response from RoyB note that the 50A service is 240 single phase AC with two hot legs at 180 degree opposite phase .at the 30 A end (see his sketch ) only one of the hot phases is connected ( 120v and neutral ). Accordingly, only the breakers in the RV Load Center connected to that phase can be operated. Breakers in the Load Center connected to the other phase bus bar are thus not powered and their connected loads will not receive power per the sketch.

Look again. The 50 is the male and the 30 is the female. The 30 male mate for it has a breaker box with all the breakers connected to this one hot leg.
If it were the opposite like you're thinking, then there would be a jumper across the hot legs of the 50amp female and thereby providing power to both legs in the box, even though of the same potential and limiting usable power to 50%.

In reviewing the response from RoyB note that the 50A service is 240 single phase AC with two hot legs at 180 degree opposite phase .at the 30 A end (see his sketch ) only one of the hot phases is connected ( 120v and neutral ). Accordingly, only the breakers in the RV Load Center connected to that phase can be operated. Breakers in the Load Center connected to the other phase bus bar are thus not powered and their connected loads will not receive power per the sketch.

jhilley wrote:
It's no different than plugging an 18 gauge extension cord into a 20 amp receptacle. It is after all an extension cord and not directly wired.

I agree and the only thing with extension cords per say, is that they're supposed to be completely visible and not hidden behind walls and such. A rule that's not always followed and other misuses have caused a few fires, I'm sure.
Again, I'm totally in agreement with the theory here, otherwise I would have never put a 50amp plug on my 30amp cord to begin with.
Even though unrelated, I also installed a dual power adapter of sorts, using a 20amp plug and outlet for splitting the rear A/C circuit. This enables me to plug into a separate pedestal outlet for the rear air, thus taking some load off of the main shore service.
This in effect does the same thing as running the coach with the gen set and the way it's automatically setup for doing this same thing, since the generator is capable of at least 45amps and has it's own 20amp breaker for the rear air conditioner.

It's no different than plugging an 18 gauge extension cord into a 20 amp receptacle. It is after all an extension cord and not directly wired.

holstein13 wrote:

tropical36 wrote:

Yes, I thought so and really like using it much better. Some will nitpick about the 50amp breaker for protecting the smaller cord to the interior's main, but no different than using one of those dog bone 50/30amp conversion cords like the OP is talking about and pretty far fetched for it to ever cause a problem when you get right down to thinking about it clear through.
Just have to be sure and wire it right, so as not to supply 240vac to a 120vac coach.

This is a great idea and should be no risk at all. You will only draw 30 amps maximum anyway because your entire coach is protected by a 30 amp breaker so you are just fine. Your cord will suffer no ill effects at all. It's not as if 50 amps is pulsing through there and being limited by the breaker on your coach.

But please don't share your idea with too many folks. I have to use 50 amp on my coach and I don't want everyone wearing out our nice tight functioning outlets at the campgrounds.

Only thing is, it's a matter of proper procedure and with just #10awg wiring between the 50amp pedestal breaker (should be 30amp) and the rig's main 30amp breaker, it not properly protected. Now having said that, a direct short between these two points will trip the 50amp instantaneously and it's pretty far fetched to have a situation where there could be a steady overload above 30amps between these two points. Like I said, it's no different than using a 50/30 conversion cord and evidently UL approved, so.....

tropical36 wrote:

Yes, I thought so and really like using it much better. Some will nitpick about the 50amp breaker for protecting the smaller cord to the interior's main, but no different than using one of those dog bone 50/30amp conversion cords like the OP is talking about and pretty far fetched for it to ever cause a problem when you get right down to thinking about it clear through.
Just have to be sure and wire it right, so as not to supply 240vac to a 120vac coach.

This is a great idea and should be no risk at all. You will only draw 30 amps maximum anyway because your entire coach is protected by a 30 amp breaker so you are just fine. Your cord will suffer no ill effects at all. It's not as if 50 amps is pulsing through there and being limited by the breaker on your coach.

But please don't share your idea with too many folks. I have to use 50 amp on my coach and I don't want everyone wearing out our nice tight functioning outlets at the campgrounds.

@ frankdamp Its not about getting more power to the rv its so if your running the A/C and micro. at the same time we don't blow a backer. both only give you 120volts but the 50amp can hold the load better then the 30amp.

Your RV draws the amount of current it was designed for. If it's a 30A rig, that's its limit. If you're plugged into a 50A outlet through an adapter, the rig is still limited to 30A of service by its internal system limitations.

Consider voltage as "electrical pressure". If your system is limited to a certain flow rate (amps) because it was designed to work on 30 Amps, that's all it will consume. The "pressure" is not an issue. It can't force more electricity into your rig than it can consume.