Sunday, December 3, 2023


RV Electricity – Just Ask Mike (J.A.M.): Another combo voltage and 3-light tester recommendation

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 Readers,
Last month I wrote about a nifty outlet tester that included a voltmeter in addition to the three lights showing basic polarity and grounding. While it worked well, and would easily survive over-voltage (up to 240 volts) conditions, it wasn’t available over the counter.

However, that changed last week when I was notified of a similar outlet combo tester by Kobalt that’s available in many Lowe’s stores for about $10. As you can see it combines the function of a 3-light tester along with a basic digital voltmeter. I’ve tested this on my bench running for a day at over 150 volts (because I can) and there were no signs of overheating. However, in the user’s manual it states it should be used for a maximum of 5 minutes testing. But I think that’s just legal talk since there’s nothing to wear out or overheat that I can find.

In addition, this is an ETL listed product (which is essentially the international version of UL listing) and it’s sold by a big corporation, so that should assuage any fears that it could be a piece of imported junk. It looks and feels like a rugged piece of handyman’s gear that should survive bouncing around in your road kit for years. Nice deal for about $10.

As in my previous article using a different tester, the only real drawback that I can find is that the ground pin is designed for an outlet oriented in traditional “ground-down” configuration. And as we all know, receptacles (outlets) on campground pedestals are required to be mounted with a “ground-up” configuration. If you want to see what the voltage reading is you’ll need an adapter cord of some sort.

So you can get a 30-to-15-amp puck adapter, but may need to stand on your head to read the voltage numbers. However, I think a better solution is to get a 30-to-15-amp dogbone adapter that allows you to twist the display around for viewing.

Click the video link to see me using a non-polarized outlet meter with a 30-amp puck adapter for basic pedestal testing. Or click HERE.

Where to get one? Looks like Lowe’s is the only place it’s available right now, and it’s not carried in every one of their stores. But they do have an online ordering system where you can have it shipped for free to your local Lowe’s store for pickup. Just look up Kobalt Digital 30-250V Test Meter to check if it’s in stock at your local Lowe’s. 

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




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Mike Ingram (@guest_83324)
3 years ago

I just realized that my question does not appear as a new discussion but as a comment to your most recent blog post. Please move this where it needs to be, or let me know where to post new questions.

RV Staff
3 years ago
Reply to  Mike Ingram

Hi, Mike. I think (other) Mike will respond here when he has a minute to catch up. 😀 —Diane at

Mike Ingram (@guest_83322)
3 years ago

I need help determining my next troubleshooting step. I am popping the outlet on my RV storage space just by plugging in my RV. I have a 50 amp RV and am stepping down the cable to 30 amp and them to a 110 adapter to plug it in to the 15 amp pedestal.

I have narrowed down the problem to one of the neutral wires on the neutral bar in the breaker box. The issue goes away when I disconnect either the main white wire from the bar, or a particular smaller wire connected to the bar, which I assume is related to a specific circuit in the RV.

When that one neutral wire is disconnected from the neutral bar the outlet on the pedestal does not pop. However, in this state my house battery is no longer receiving a charge from the converter.

Since I cannot visually see where this neutral goes, I’d like some direction in how to locate the correct circuit and find the problem.


Mike Ingram (@guest_83353)
3 years ago
Reply to  Mike Sokol

Thanks, I’ve put in a join request at the group and will post this there. Although I don’t understand the danger completely, I did reconnect the neutral wire in question after determining that disconnecting it stopped the pedestal outlet from popping. Thanks for the warning though.

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