30 amp service for 50 amp bus

[eagle19952]

So what will this give you....30A on one leg and 15A on the other ?

Will it provide 240V ?

or 45A on each leg @ 120V or 240V...or what ?

[Sean]

So what will this give you

That is basically the same "two-fer" device I was describing in my earlier post.  Some versions have a box with a receptacle and two cords, where others, such as the one pictured, have a fully molded "Y" adapter with the receptacle and two plugs.

....30A on one leg and 15A on the other ?

In this case, yes, because that's how the manufacturer chose to build it.  Many models have two #10 AWG cords with TT-30 plugs; this model appears to have one #10 with a TT-30 and one #12 with a 5-15P.  So that's all you get with this model.

It has the advantage of not being able to exceed the neutral rating, as described above, since even if you connect the two plugs to the same leg, the neutral current would be at most 45 amps.  The disadvantage is that you have no control over which side of your panel gets the 15 amps, and which side gets the 30, so if you own one of these adapters, you probably need to figure that out and arrange your panel loads accordingly.

Will it provide 240V ?

Yes, if you connect the two inputs to opposite legs of the shore power.  However, you'd have only 15 amps of 240, with an additional 15 amps of 120 available on the larger leg.

or 45A on each leg @ 120V or 240V

Nope.  It would be 5,400 watts total, which is equivalent to 45 amps of 120.  But it's spread across two legs, so you get one leg of 30 and one leg of 15, whether they are on opposing legs or not.

Make sense?

-Sean
http://OurOdyssey.BlogSpot.com

[bwze]

Also, not to state the obvious to those who already know, but to those who do not, the adapter pictured above will not work as designed with a GFCI outlet.....

[eagle19952]

Pretty much as I thought, Thank-you.
I have seen some pedestals where the 15 amp common is simply a jumper wire from the 30 amp.
and have seen labeling to use either or and not both.

[bwze]

Following up.....

In an earlier post, I mentioned a ticket that I submitted to the vendor from whom which I purchased my adapter. In said ticket, I asked if the adapter that I purchased was supposed to work as one would expect...taking a single hot leg 30 amp service and adapting it to provide power to both legs of a 50 amp service (hoping that I just got a dud). I got a simple answer from them......"no".......(that's their actual reply by the way). So, I recommended that they possibly reword their description to make it clearer to customers that this adapter didn't work as one would expect and I also inquired that since it didn't work as one would expect, what was it's intended use. The answer this time was....."how much clearer can the ad be when it says: If RV is wired normally it prevents the use of the 20 amp side of RV panel"......(again, their actual reply). Now I've answered their retort with something a little more "to the point", but it's becoming clear that my purchasing power just doesn't necessitate the need a more thorough explanation and that I must be an idiot for not knowing which side of my 50 amp service is the 20 amp side. After the fact, I decided to call and speak with an actual person......when I explained the situation and asked his opinion, he agreed with me wholeheartedly....didn't make any sense at all and he didn't know what you'd use it for either. When I asked what my options were, he let me know that I could request an RMA number to return it to them.....at my cost. Long story short, I'll make a trip to Camping World, as I should have done in the first place, to get an appropriate adapter, and I'll keep this one as a memento and as proof positive that when dealing with a 50 amp service....you have a 30 amp side and a 20 amp side....and you better know which one is which when the time comes

[bevans6]

I'm so low tech...  I just plug my bus into the 30 amp plug and my block heater into the 15 amp plug... and away I go   

Brian

[Lin]

Is it common for RV parks that do not have 50 amp service to run separate lines off different legs for the 15 and 30 amp receptacles, or would you be most likely on the same leg most of the time?

[bobofthenorth]

Is it common for RV parks that do not have 50 amp service to run separate lines off different legs for the 15 and 30 amp receptacles, or would you be most likely on the same leg most of the time?

Typically a pedestal will either have 50, 30 and 15 service or just 30 and 15 service.  You can assume 99.99% of the time that the 30/15 service will be on the same leg.  If they had gone to the bother of running two legs to the pedestal they would have put in a 50 amp plug (and charged accordingly).

[Lin]

Bob-- that's what I was getting at, but certainly don't know for sure.  The adapter could still be useful for increasing capacity, I suppose.

[bobofthenorth]

I have a homebuilt version that I carry with us and use maybe 5 nights a year.  We always use it when we stay at one particular friend yard where the power source is the tractor shed out of 15 amp outlets on a fuse box.  I suppose we must have used it on a 30/15 service at some point but I find it much more useful for combining 2 x 15 amp outlets.

[Oonrahnjay]

I have a homebuilt version that I carry with us and use maybe 5 nights a year.  We always use it when we stay at one particular friend yard where the power source is the tractor shed out of 15 amp outlets on a fuse box.  I suppose we must have used it on a 30/15 service at some point but I find it much more useful for combining 2 x 15 amp outlets.

Bob, do you mean that you plug into a 15-amp outlet on one breaker circuit and a 15-amp outlet on another breaker circuit and thus get a total of 30 amps feed into your bus (sorry, if this is a stoopid question, electrical stuff isn't my strong point).  If so, it sounds like a good plan if you're confronted with several usable circuits but none rated at more than 15-amp (@ 120v).

[bobofthenorth]

Bob, do you mean that you plug into a 15-amp outlet on one breaker circuit and a 15-amp outlet on another breaker circuit and thus get a total of 30 amps feed into your bus (sorry, if this is a stoopid question, electrical stuff isn't my strong point).  If so, it sounds like a good plan if you're confronted with several usable circuits but none rated at more than 15-amp (@ 120v).

That's exactly what we do.  It works for us because our big power hog is an electric water heater which is on one side of the panel so by doing it this way we put the water heater off by itself and leave the "other" 15 amps for regular use.

[Oonrahnjay]

Bob, do you mean that you plug into a 15-amp outlet on one breaker circuit and a 15-amp outlet on another breaker circuit and thus get a total of 30 amps feed into your bus (sorry, if this is a stoopid question, electrical stuff isn't my strong point).  If so, it sounds like a good plan if you're confronted with several usable circuits but none rated at more than 15-amp (@ 120v).

That's exactly what we do.  It works for us because our big power hog is an electric water heater which is on one side of the panel so by doing it this way we put the water heater off by itself and leave the "other" 15 amps for regular use.

Thanks, Bob.  Sorry to have to ask more questions but I'm trying to completely understand this.  What kind of cord do you use for this setup?  Do you have a "Y" connector as shown in this thread?  When you're in a campground that has the full array of sockets, do you plug into the 50-amp socket and provide 240-v power and split it into two 120 legs on the bus (or is your bus set up for 120-v power into it)?

[bobofthenorth]

Thanks, Bob.  Sorry to have to ask more questions but I'm trying to completely understand this.  What kind of cord do you use for this setup?  Do you have a "Y" connector as shown in this thread?  When you're in a campground that has the full array of sockets, do you plug into the 50-amp socket and provide 240-v power and split it into two 120 legs on the bus (or is your bus set up for 120-v power into it)?

And I apologize too - this board moves too fast for an old guy.

My cord is a homebrew but it is essentially the same "Y" connector you refer to.

If 50 amp is available we'll use it.  We won't pay extra for it though because we're pretty happy with 30 amps.

The root of your confusion is likely summed up in your last question.  50 amp is 240 volt service and that gives us two legs of 120 volts @ 50 amps.  We do not have any 240 volt equipment onboard.  On a 50 amp service you can pull up to 50 amps on each side or leg of the panel, IOW a total of 100 amps @ 120 volts.  When we are on a 30 amp pedestal we have a total of 30 amps @ 120 volts available for all onboard uses.  IOW that 30 amps feeds both sides of the panel and can be drawn 30 amps on one side or 15 amps per side or 10+20 or whatever.  When we use my cheater box we have 15 amps per side - no more, no less.

The difference between a 30 amp combiner and a 30+15 cheater is that the combiner feeds both legs off the same 30 amp service.  The cheater on the other hand keeps the legs separate so in our situation when we are using 2 x 15 amp outlets we only have 15 amps per leg.

Clear as mud??

[Oonrahnjay]

(snip)  Clear as mud?? 

Actually, clear as cold water!  Thanks.  I'm never going to be one of those people who gets himself in trouble by thinking that he "knows enough about electricity" but this is explained clearly enough that even I can understand it.

I'm also going with no 240v loads on my bus.  120v, nice and simple all the way.  That's why I'm really interested in learning how to feed it off a 240v socket.

I also expect to have a number of times where I'm working with only a 15A feed circuit (or maybe two different 15A feed circuits), so this is interesting to me, too.

Appreciate the info.  BH NC USA