RVelectricity – Just Ask Mike (J.A.M.): How to fix an open ground problem with a generator

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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) noshockzone.org with the subject line – JAM.


Join Mike Sokol from RVelectricity and Danny Rahner from SoftStartRV™ Tuesday evening, February 16, beginning at 8 p.m. Eastern time (5 p.m. Pacific), for Mike’s next “Ask The Expert” YouTube Live Webcast. Danny is SoftStartRV’s lead help desk installation expert. If you have any questions about how to hook up a SoftStartRV to any RV air conditioner, you’ll be able to text him questions in real time. Here’s a link to Mike’s announcement and the link to set a reminder. To learn about what SoftStartRV can do for you, read these earlier posts: RVelectricity: More on how SoftStartRV works and  Use your RV air conditioner in low-power situations.


Dear Mike,
We have a 2500 inverter generator. When we plug the surge protector into the generator it gives an open ground code. Do I need to use the surge protector with the inverter generator? If not, can that open ground fry components in my RV? Also, is there a way to ground the generator? Thanks. —Leslie

Dear Leslie,
This appears to be a “riddle wrapped in a mystery inside an enigma; but perhaps there is a key.

And that key is the use of the word “ground” for all sorts of electrical things that have little or nothing to do with actual earth ground. The “open ground” indicator light on your surge protector is one of them.

Portable generators powering an RV don’t need an earth ground

That’s right… Even though every generator I’ve ever looked at has some sort of lug or connector that can be hooked to a ground rod, that’s a very rare requirement. Any portable generator used to power your RV simply does not not need to be connected to a ground rod. In fact, NEVER drive a ground rod into the dirt without first checking with your local “Miss Utility” group to make sure you don’t hit an underground pipe or wire.

Even good generators can go bad

I’ve seen a lot of off-brand generators go over-voltage and burn up whatever they’re connected to. But a few months ago I was made aware of a brand-new Honda EU3000 generator going up to 185 volts, which damaged some appliances.

This is doubly true if you’re using any 5,000- to 7,500-watt generator with a split-phase 120/240-volt output. An open neutral will allow the 240 volts to divide unevenly. So instead of 120/120 volts, it could turn into 40/200 volts. And, yes, the expensive stuff will be on the 200 volts leg. Therefore, I think it’s a good idea to always use a Total Protection (EMS) Surge Protector on any shore power or generator connection.

Open ground doesn’t mean open earth-ground

What it’s really indicating is the lack of a Neutral-Ground bond, which is normally supplied by the power company service panel feeding your campground or house. Since nearly all inverter generators have a floating neutral, plugging in a surge protector to one of these generators will indicate “open ground.” However, what they really mean is “open bond.” You can get the same warning from a $5 outlet tester that has 2 amber and 1 red light.

Will an open ground on a generator fry anything in my RV?

No, an open ground on a generator won’t fry anything in your RV. But some appliances (such as refrigerators or furnace controllers) may interpret this open ground/bond condition as dangerous (even though it isn’t when running from a generator) and refuse to operate.

Is there a quick fix to an open ground generator?

Yes, there sure is a quick fix to an open ground on an inverter generator. In fact, I invented this little trick about 10 years ago, and it has been used many thousands of times to correct this issue. It’s simply an Edison plug that’s wired with an internal Ground-to-Neutral jumper wire, which provides a local Neutral-Ground bond.

Southwire now sells one for around $12 on Amazon (and other places). However, you should only install this generator bonding plug into a spare 15-amp outlet on your generator (never into an outlet in your RV). There’s nothing really strange about this. That’s exactly how any on-board RV generator is wired through the transfer switch. Amazon has them for sale HERE.

Want to see how it works?

If you want to see how it works, watch this video. In it I demonstrate how a Progressive EMS Surge Protector and a 3-light outlet tester show an open ground on a Honda EU3000 inverter generator.

Connecting into a floating neutral generator causes the Progressive EMS Surge Protector to shut down power. You correct this by plugging in my G-N Bonding Plug. It’s a simple but very handy device. Please note that a G-N bonding plug must ONLY be plugged into the generator itself, NEVER an outlet in your house or RV.

What about when I’m plugged into shore power?

Anytime you get an open-ground indication while plugged into a campground or home electrical outlet is an indication that your RV’s safety ground connection has been lost. It also means there could be a potentially dangerous hot-skin voltage on your RV.

So, in that case you need to unplug and find the reason for the lost EGC (Equipment Grounding Conductor), commonly referred to as the Safety Ground. Read more about troubleshooting a hot-skin condition 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 Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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William Steenbergh
13 days ago

Mike — As always, thanks for your assistance and explanations. I went to the Amazon link in your answer, but there is a comment saying to only use this device for generators up to 5000 watts, as anything larger is already bonded together internally in the generator. Could you please clarify? Thanks

Mike Sokol
12 days ago

That’s true for many contractor (non-inverter) generators, but definitely not true for inverter generators. For example, my Honda EU7000is has a floating neutral, as I’ve described.

Drew
13 days ago

Mike,

Sorry, forgot to say that the generator is the on board style.

Thanks!

Drew
13 days ago

Mike,

So just to clarify- you DO recommend a surge protector on the generator output before the shore cord or immediately after the transfer switch…is that correct?

Thanks, Drew

Drew
12 days ago
Reply to  Mike Sokol

Understood, thanks!

David Telenko
13 days ago

Hey Mike great advice! What the heck is that German typewriter looking device that you’re showing, very weird but very interesting to my curious eyes! Ending in “mit 12mm”

Snoopy

Irv
13 days ago
Reply to  David Telenko

It’s a german Enigma code machine from WWII. It’s an interesting story, look it up.

David Telenko
13 days ago
Reply to  Irv

Hi Irv, very interesting story of his life, though his ending is so sad! Thanks for your information!
Snoopy

Diane Mc
8 days ago
Reply to  Mike Sokol

I got it!

Mike Sokol
1 day ago
Reply to  Diane Mc

I’m now a student of history, even though I came close to flunking American history in high school. That didn’t go over well with my dad since he was an American history teacher (but thankfully not mine). 😳