combining 30/20 amps

[Dan]

Someone markets an electrical cable that will attach to both the 30 amp and the 20 amp coming off the service line. In essence this will create 45 amps to the coach. Can someone tell me the name of the product?

[UFO Pilot]

Check out 50-Amp RV Box Adapter

[K-Star]

I have seen this device too. I think CW seels them too. However, I do not believe this will give you the 45 or 50A service you are looking for but rather 30A on one leg and 20A on the other leg. Not a true 50A connection.

[Ray,IN]

If the 30 and 20A receptacles are on the same 30A circut, 30A is the maximum you'll get regardless; then the CG post breaker trips out.

[RV Wizard]

Also if the 20 amp receptacle is on a GFCI it will not work; tripping the circuit feeding the 20 amp side.

[Gary RVRoamer]

I have one and they work, subject to the limitations mentioned earlier in this thread. One more caveat: if you have an Energy Mgm't System that sheds loads when on 30A supply, it will continue to do so unless the 20A source is out of phase with the 30A source, prohibiting you from taking advantage of your extra 20A. However, it is possible to wire a defeat switch into the Intelletec EMS because it has a built-in override mode for use with 50A+ generators that have matched phase outputs (e.g. the Onan 7.5kw Quiet Diesel). Not for the average Joe, but those with good electrical skills can do it easily enough.

[wittmeba]

Look at this picture and it may explain why as Ray indicated, you may only get 30 amps max.

The actual amount of current you can draw is totally dependent on how the pedestal is wired.

If wired like the top part of the image, if they are both connected to a single 30 amp breaker, you can only draw 30 amps total. If wired per the bottom part with a separate 30 amp breaker on the 30 amp lines and a separate 20 amp breaker on the 20 amp lines, then you can draw 30 and 20 amps.

[slabman]

I understand Ray's post. My question is what others have found is more common? Separate circuits for the 30 and 20 amp outlets....or both wired to the same feed source? It strikes me that if the max. amperage is 30 at a pedestal, the electrician would have only used enough wire gauge to deliver that amperage, thus there'd be no extra current flow available for the 20 amp circuit. In this case, this converter would do no good. So how often might one find a situation where it WOULD work?

[porscheracer]

If you are both diligent and lucky, they CAN act as a true 50A supply. You have to find a pedestal with multiple outlets, and then determine which ones are on separate legs.

Many older MH's don't have "smart" systems, and will accept input from both can still get 50A service without worrying about the supply legs. On newer systems, if both inputs are on the same leg, your control panel will only show 30A service. If you get on separate legs, it will show 50A, and you can use all of it.

BTW - I own one of the boxes, and this is all based on both a working knowledge of electricity and experience, not just theory and / or hearsay.

[Tom N]

Quote:

Originally posted by porscheracer: If you are both diligent and lucky, they CAN act as a true 50A supply.

30 and 20 amp circuits can never be wired to act as a true 50 amp RV circuit. A 50 amp RV circuit is 2-50 amp circuits.

-Tom

[RustyJC]

Quote:

Originally posted by Tom N: <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by porscheracer: If you are both diligent and lucky, they CAN act as a true 50A supply.

30 and 20 amp circuits can never be wired to act as a true 50 amp RV circuit. A 50 amp RV circuit is 2-50 amp circuits.

-Tom </div></BLOCKQUOTE>

Yep, to confirm this, check the breakers for 50 amp service in the shore power box or in the RV's power distribution panel (breaker box). True 50 amp service is protected by 2 each linked 50 amp breakers, not a 30 and a 20. True 50 amp service has a theoretical ampacity of 100 amps (2 legs x 50 amps per leg).

Rusty

[Ray,IN]

Right!

[bldrbob]

I assembled a cheater box. the problem is the 20 amp receptacle is a groundfault and trips.The only way it would work is if you only used the 30 amp plugs on two separate pedestals.I don't think the campground would like you running a cord to another site.
BOB

[Gary RVRoamer]

Quote:

I don't think the campground would like you running a cord to another site.

I have one of those boxes and can testify that at least one campground does not. Had an irate manager pounding on my door at daybreak when he saw it on his morning rounds (but I got to run the rear a/c one extremely hot afternoon and evening when we desperately needed it). But I'm using mine right now in my yard so I can power the water heater in addition to the primary house circuits without popping the 30A source. The 20A leg is plugged to a separate outlet on another circuit using a 12 gauge extension cord to reach it.

I also installed an override switch on my Smart EMS so that it will accept 30/20 legs of the same polarity without limiting to 30A total. Basically I made the EMS think the generator is running, which makes it shut off its power shedding function.