Monday, December 4, 2023


RV Electricity – Just Ask Mike: 50-amp test plug

By Mike Sokol

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) with the subject line – JAM.

Dear Mike,

Can someone give me a place to purchase a test plug with 50 amp to a Y with 15-amp outlets on each side? I want to test that L1 goes to one side of the Y and L2 goes to the other side. The one I purchased on Amazon sends L1 to both sides. I questioned them about it and they said that is the way they wire it up, which means to test for 110/120 at the end of each side is not possible. I think you mentioned where to get one in a blog post but I can’t find it anywhere. Thanks in advance. —Joe Testa

Hey Joe,

This one did take me a while to find, so I’m not surprised you’re having difficulty finding one with the right wiring configuration. I’ve just called their tech support desk and they confirm that each of the 20-amp outlets is wired to different hot legs on the male 14-50 plug, so this one should do the trick. You can get it from Amazon HERE.

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….



Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at For more info on Mike’s qualifications as an electrical expert, click here.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.




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Calvin Wing (@guest_55590)
4 years ago

Hi Mike, thank you for a most informative service. I have a question that I’ve never seen addressed. The standard dog bone adapter takes the 30 amp circuit and couples it to the 20 amp circuit in a pedestal offering 50 amps, except I’ve never found one that works due to it causing a back feed causing the GFI circuit breakers to trip.
What if I remove one of the AC units power supply lines from the coach’s breaker box, run it through an independent circuit breaker box and then have a separate power cord for just that AC unit and plug it into the 20 amp outlet on the pedestal? The pedestal’s 30 amp circuit would power everything else and I wouldn’t have to resort to paying for 2 $300 electronic power modulation devices. And if my idea is feasible then why doesn’t the RV industry offer this option as standard equipment?
Thanks for your input Mike

Karl Eby (@guest_55521)
4 years ago

Am I missing something here.
Couldn’t he just check his voltages at the 50 amp outlet and save $60.00?
I personally don’t know that I would want to plug anything into the 110 volt pigtails of this adapter as it’s going through a 50 amp breaker.
Not much protection if there’s an electrical problem with what I’ve plugged in and using.

Joe Testa (@guest_55527)
4 years ago
Reply to  Karl Eby

I am the original asking party. The idea here was to cater to those who are not comfortable sticking probes into outlets. Not everyone is as savvy with electricity and since it is something that for all intents and purposes is invisible to most people, it is just there until you do something wrong and then you potentially learn the hard way.

What I am doing is producing a series of videos to show people how to take what would be a normal 50 amp plug and with the two 20 amp ends to check for correct voltage and possibly mis-wired outlets using a tool instead of voltmeter probes.

It is NOT to be used for anything other than that, testing the 50 amp outlet.

Feel free to reach out if you’d like to see the video series once it is completed.

Mike thanks for the link, I ended up building what I needed yesterday.


Joe Testa (@guest_57629)
4 years ago
Reply to  Mike Sokol

Mike sounds good, I got it built, just need to go out and test and video it, but it is cold here in Ohio 🙂 Soon as I got it done, I’ll gladly send it to you.

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