Power Y Adapter, (2) 30 Amp Male to 50 Amp Female

[Senator]

I purchased one of these adapters to use at a campground later this month.  The power pole at the site has 2-30 amp receptacles, and the owners said that they both can be used.  I know the danger of the setup if only one side is plugged in, and I am willing to take the risk for the few seconds that that condition will exist.  I will of course change my mind if I get electrocuted...

As I was thinking about other campgrounds, I have seen an extra 20-amp receptacles on some posts in my limited travels.  They may have a 30-amp and a 20-amp receptacle on the same post.

Assuming that there is enough power to the post to actually run a full 20 and 30 amp draw, should I be OK using an 30-amp to 20-amp adapter on the 20 amp side of the post?  So I would have 20-amps on one leg, and 30 amps on the other?

Since my 50-amp 5th wheel is really 2 legs of 110v, not 220V, I do not see a downside.  Am I missing something?


https://www.amazon.com/gp/product/B0756QF5WL/

 

[John From Detroit]

We will try again...
I have one of those boxes they are safe to use....

On my RV the Generator is a 5500. max output for both legs COMBINED is 50 amps.

And though I have tripped 2 50 amp breakers (one was very defective) that's in 13 years of RVing.

The "Danger" in using those is that the neutral is rated for 50 amps and you can. in theory. suck 60 amps on that wire. but that's only a 20% overload and even then the odds are you will never get that high. like I said my generator is only 50 amps MAX.

THe problem with that box i in most parks you do not have two 30 amp outlets but one 30 and one 20 amp GFCI. and that box makes a great GFCI tester. will trip it faster than you can blink

ONE park I've been to all the 30 amp outlets (and another half of them) are GFCI.. at the 2nd (Which is history by the way) I used to be able to pick a spot where I could grab a pair of NON-GFCI 30s and it worked.

One other park is a Grandfatered (some sites) do not have GFCI. others do.  It works on the two that do not.

 

[HappyWanderer]

There may be both 30 and 20 amp outlets, but it could be a single 30 amp circuit feeding them.

You can use 30 or 20, but not both at the same time.

 

[NY_Dutch]

With the 'Y' adapter plugged in to both the 30 amp receptacle and the typical GFCI 15-20 amp utility receptacle in modern RV park boxes, the GFCI will pop due to the common neutral being seen as a current imbalance. There's also very little danger in only plugging one side in, since the other unconnected side is only connected to the second 50 amp hot leg. That will also leave you with only partial power to your RV though, where a standard single 30/50 adapter will feed the one 30 amp hot leg to both 50 amp hot legs, supplying power to the whole RV, albeit at a reduced current capacity of course.

 

[Gary RV_Wizard]

Agree with the previous comments. It is almost universal that a 30+20 power pedestal will be served by a single 10 gauge (30A) feeder, so it is possible to overload it if you actually try to draw 30A on one side and 20A on the other.  The feeder wire may have a 30A breaker upstream as well.  Other than tripping the feeder breaker (if any), the risk is to the campground wiring rather than your rig. There is also a possibility of voltage drop at higher loads, but that's a risk you should be prepared for anyway (a power line monitor (aka surge protector) is recommended).

Most newer or upgraded campground pedestals will have GFCI type 15/20A outlets to comply with recent electrical codes, so they will trip as NY Dutch warns.  Very new pedestals may have GFCI on the 30A as well (usually on the breaker rather than the outlet, though).

I've used Y-connectors extensively, both with jury rigs multi-outlets and campgrounds with two 30A outlets (buddy sites).  They work great as long as you understand the limitations.  One warning, though.  If either of the outlets have neutral and hot reversed, you are going to have some brief excitement as the 30A feeder shorts out.  It happened to me when using twin 30A outlets wired by some local farm boys masquerading as electricians. After that, I did a polarity check before plugging in my Y adapter.

 

[Senator]

One warning, though.  If either of the outlets have neutral and hot reversed, you are going to have some brief excitement as the 30A feeder shorts out.  It happened to me when using twin 30A outlets wired by some local farm boys masquerading as electricians. After that, I did a polarity check before plugging in my Y adapter.

Great point!!

I am going to try it and see.  I know the one campground said they have a full 30-amp on each leg, any other campground that I can use it will be a bonus.

I do see now that Amazon sells a 30-amp & 15-Amp 'Y' cord.  I can 'make' one with my 15-amp adapter and my 30-amp 'Y' cord.

 

[Gary RV_Wizard]

Mine came with twin 30A plugs plus a 30/15 adapter.  I've even used it with two 30/15 adapters (plug to separate 15A outlets).

 

[Senator]

I was able to use my 'Y' cord when I had two 30-amp outlets.  When I tried it with a 30/15-amp setup, with a GFI, it tripped even when teh cord was not attached to the RV.  That was expected.

I also tried it here in Canada, where they do not have GFIs.  It worked for a short time, then tripped.  Even when running less 'stuff' than when I run on 30-amp alone.

I would have thought it would pull only what it could from each side, and not blow a circuit.  It appears maybe the load is balanced and when I an using ~32 amps it puts 16 to the 15 amp side?

A mystery for now.

 

[Senator]

I used my Ohm meter to see what was happening.  The hot side of the 30-Amp plug went to one of the legs of the 50-amp adapter.  The hot from the 15-amp side went to the other side of my 50-amp adapter.  The two hot sides are not connected at all.  They share a neutral and ground.  So it's possible to blow the 15-amp side using only 15-amps total.

It makes sense, but makes it near impossible to use with a 30-amp and a 15-amp dog bone.  Unless I can figure out, and segregate each side and monitor what gets used...

I am not sure why both hot legs cannot be tied together.  Any ideas?

 

[Gary RV_Wizard]

You are correct - each of the Y plugs feeds one of the hot legs.  You can identify what inside the RV is on each leg (it's often obvious from the layout of the breaker panel) and you can reverse the Y-plus to put the lower amp load on the 15A side.  There is no magic - if you only have 45 amps (30+15) to start with, that's all you can use.  Even twin 30A outlets is less total than what you have on a standard 50A outlet (which yields 2 x 50A hot legs).

Right, no GFCI outlet can be used. The shared neutral of the 50A shore cord makes that impossible.

This gets fairly deep technically:  The hot legs cannot be "tied together" unless it is first verified that the two 120v sources are "in phase". Standard split phase power wiring has two legs 180 degrees out of sine wave phase. That means any two outlets may show 240v between their respective hots.  If you plugged out-of-phase legs together, you will burn out any 120v devices attached.  You can test for that with a meter ahead of time, but it only takes one mistake to cause major damage. No commercially made Y-adapter will leave that to chance, an I strongly recommend you do not make one that way either. Sooner or later you will mess up.

 

[John From Detroit]

I would have thought it would pull only what it could from each side, and not blow a circuit.  It appears maybe the load is balanced and when I an using ~32 amps it puts 16 to the 15 amp side?

When you are using one of those "Y" or Cheater boxes they connect the NEUTRAL and Safety Ground leads to both outlets but the HOT leads are one to a plug. that is they are NOT connected together One goes to L-1 one to L2.

WHY.. Well if you are plugging into two 30 amp outlets there is a chance the park has "Balanced" so one is L-1 and the other is L-2 and if you shorted those two hots.. FIREWORKS time.. (240 volt short).. So each plug feeds ONE side (or the other) of your power system.

Next time you are on a 30/30  Turn off ONE breaker and see what works and what does not. Label the adapter as to that. Then do the other side

Or turn off one and label the other with what works and the off one with what does not..

You can shortcut if you have two A/C's but just noting which A/C works then going 1-2-1-2 on the circuit breaker panel.