Do two 30's make a 50?

Can you add two 30-amp pedestal outlets together to make a 50-amp service?

Hi Mike:

I don’t recall you covering this in the past, but if you have, I apologize. My friend is a seasonal camper with a trailer that sits year round in a park in NY. It is 50 amp, but his pedestal is only 30 amp. The site next to his is unoccupied. 

He has attached a line to both sites’ 30 amp pedestals, and run them thru a Y to his 50 amp trailer, proclaiming he now has 50 amps and can run both air conditioners. Is this legal? Smart? And most importantly, safe?

Thanks - Jim E

Hey Jim,

No, I don’t think I covered that directly, but I have done a few dog-bone articles that hinted how this can be accomplished. But first you have to be aware that you’ll be using up to twice the electricity the campground has intended to supply you, and which they’re paying for. So if they don’t have a problem with it, then here’s how it works.

You need a 30/30-amp Male to 50-amp Female dog-bone Y-adapter

Lots of manufacturers make a 30/30 to 50-amp Y adapter. You can find one example on Amazon HERE.

Yes, this type of Y-cable does indeed allow you to double the amount of current and wattage available from a single 30-amp pedestal outlet. So you’ll get 30 + 30 = 60 amps, which is 60 x 120 = 7,200-watts of power.

Now technically, if both pedestals you’re connecting to are on the same leg of the split-phase service then your RV’s 50-amp neutral conductors and contacts could carry up to 60-amps of current. But that’s probably okay unless you’re at near continuous current draw on both legs. The dog-bone manufacturers I’ve talked to aren’t worried about it, but I’m just bringing this to your attention.

So will this work safely?

Yes, as long a neither pedestal’s 30-amp outlet has reversed hot/neutral polarity. If that was the case there would be a large short circuit created as soon as you turned on either circuit breaker, resulting in a quick breaker trip.

Here’s a photo of me intentionally creating a short circuit on a 30-amp circuit breaker with an impressive arc. You really don’t want to accidentally recreate this experiment at your campsite!

Time for a polarity check!

So you should do a quick polarity check before plugging in this kind of Y-adapter between two pedestals.

Here’s an easy way to do this test with a 30-to-15-amp adapter and a standard 3-light outlet tester like the one above. Click the screenshot below or HERE and watch the short video.

Will two 30’s provide more power than a 50-amp outlet?

No, a 50-amp service actually provides your RV with 100-amps of current at 120 volts. That’s because there’s two 120-volt legs of 50-amp current each which adds up to 50 + 50 = 100 amps. And 100 amps x 120 volts = 12,000 watts. On the other hand, 30 + 30 = 60 amps. And 60 amps x 120 volts = 7,200 watts.

How does a pedestal add up?

Note that if you added up all the circuit breakers on a 50/30/20-amp pedestal it would come up to 150 amps. However it’s entirely possible that the pedestal is only supplied by a 50/50-amp split-phase feeder, so it would possibly trip an upstream 50/50-amp double-pole breaker.

Final Analysis…

As long as the campground allows you to use the extra kWh of energy (which they have to pay for) and you check each pedestal for proper Hot-Neutral polarity of the 30-amp outlets, then this should work safely. But you’ll also need a 30-amp extension cord to link the second pedestal to the Y-adapter.

Let’s play safe out there… Mike