Do 45-amp Y-Adapters work?

Probably not, and here's why. It's all about the GFCI...

Hey Mike,

You probably addressed this already and I may well have read it but I don’t remember. Do these things really work? - Kevin

Hey Kevin,

What you’re showing is generally called a 45-amp Y-Adapter, named so because it combines 30-amp and 15-amp pedestal outlets on your 50-amp shore power cord. There’s also a double 30-amp version that’s a pair of 30-amp male plugs which combine into a 50-amp female outlet.

What works or doesn’t work?

The 30/30 to 50-amp adapter is a possible solution as long as you understand the limitations. But the 15/30 to 50-amp adapter you sent me a picture of will not work with a properly wired 20-amp GFCI output. Read more below!

Yes, the 30/30 to 50-amp Y adapter probably will work!

Note that this type of adapter has a pair of 30-amp male plugs feeding a single 50-amp female outlet. However, there’s two different ways the 30-amp outlets can be wired on the pedestal(s) than can affect operation.

If the two 30-amp outlets are wired on opposite Legs of the split-phase 120/240-volt service, (One on L1 and the other on L2), then the neutral currents in your shore power cord will be subtractive so the amperage will never exceed 30-amps. This is exactly how a properly wired 50-amp outlet is supposed to work, except you’ll only have a combined current of 60-amps available instead of the 100-amps in the standard 120/240-volt NEMA 14-50 pedestal outlet.

But if both of the 30-amp pedestal outlets are wired on the same split-phase Leg (L1+L1 or L2+L2), then the neutral currents will be additive, so it’s possible that the neutral conductor in your shore power cord would reach 60 amps. While technically a code violation since that neutral is only rated for 50 amps, unless you’re pulling 30-amps continuously from both sides of your RV power it should be safe. So if you do use one of these adapters you’ll want to keep a watch on any signs of overheating on the 50-amp shore power plug.

But if one of the 30-amp outlets is miswired with reverse polarity, there will be fireworks and tripped breakers when you plug it in. Best to measure everything first. I’ll publish an article on that later.

No, the 15/30 to 50-amp Y adapter you showed probably won’t work

However, these so-called 45-amp Y-adapters that are designed to plug into one 30-amp and one 15 or 20-amp pedestal outlet just won’t work. That’s because all 15- or 20-amp outlets on a pedestal are required to have GFCI protection. And because the neutral currents between the two outlets are intermingled with this adapter, the GFCI outlet will instantly trip with any current over 5mA (that’s 0.005 amperes of load current).

So don’t waste your money, because it can’t work with a properly operating GFCI outlet. And no, you can’t just replace the 20-amp GFCI outlet on a pedestal with a standard receptacle without creating a code violation and exposing yourself to liability if the next camper gets shocked. SO DON’T DO IT!

Let’s play safe out there - Mike