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RVelectricity – Just Ask Mike (J.A.M.): Is generator bonding really necessary?

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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) noshockzone.org with the subject line – JAM. Today I discuss generator bonding.


 


Dear Mike,
I just read your article regarding generator bonding. I’m curious if using a bonding plug in a floating neutral generator vs. just using the generator as-is made any difference safety-wise?

I have a WEN 3800-watt generator and a travel trailer with no EMS. Based on your article, it seems like I can just plug and play. However, I wanted to get your opinion on whether the bonding plug somehow makes things safer for my family and/or if it allows the GFCI outlets in the trailer to work.

It seems like everything I read contradicts someone else when it comes to using bonding plugs, grounding rods, and surge protectors with floating neutral generators.

Thank you for your help!! —Rob S.

Dear Rob,
Thanks for your questions. Generator grounding and bonding is indeed a confusing issue, even for manufacturers and electricians, but here’s what I know…

If you don’t have an EMS surge protector, you may not need a bonding plug

That much is accurate. I designed (but didn’t patent) the Generator Bonding Plug to take care of the EMS open-ground failure error when powered from a floating neutral generator.

While you can’t get a hot-skin voltage from a floating neutral generator, the EMS Surge Protector assumes you’re plugged into shore power because it senses the voltage difference between the neutral and ground conductors.

GFCI outlets need a bonded generator to work

It’s true… A GFCI powered by a generator with a floating neutral won’t trip if you make contact between an energized surface and the RV chassis ground plane.

But that’s because there’s no fault current to unbalance the GFCI sense circuit and cause it to trip. So while the GFCI won’t trip, there’s actually no danger of getting a shock because there’s no fault current flow.

Without a bond in the generator, outlet testing is difficult

As you may have noticed, with a floating neutral generator powering your shore power, it’s impossible to test your RV outlets for proper ground or neutral/hot polarity.

The humble 3-light outlet tester is a great way to confirm that your inside outlets are wired correctly. It provides a great way to do a periodic GFCI test.


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Some appliances won’t work without a ground bond

I’ve noticed a number of modern appliances, like residential refrigerators and furnaces, that have open-ground sensors that won’t allow them to power up with a floating ground. So in that case, a G/N bond plug on a floating neutral generator is required.

BTW: You DO NOT need a ground rod

There’s no requirement for a grounding rod on your portable generator that’s powering your RV. Of course, that can change if you were powering a number of RVs from a large central generator. But that’s not what we’re discussing here.

Voltage readings….

The generator neutral/ground bonding plug creates what’s called a local ground plane, which allows the GFCI outlets to work, and all outlets to have the expected N-G, G-H and H-N voltage relationships.

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….

Send your questions to me at my new RVelectricity forum here.

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

You don’t want to miss Mike’s webcasts on his YouTube channel.

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Mike
2 months ago

Mike

Is there a working ‘ground / neutral’ bonding adaptor available for purchase?

Thanks
Mike

Joe
2 months ago

Mike, very good explanation. This gets me thinking about all the RV’s at the Hershey show running off of large generators. I wonder if they are driving a ground rod, Hershey having a ground grid in the lots, or using so to speak a bonding plug.

Glenn
2 months ago

A thorough explanation, as usual. Thanks.

Mike Sokol
2 months ago
Reply to  Glenn

You’re very welcome…

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