Do you need to ground the generator?

[Bill M.]

Have run mine a maybe 8 times with the trailer plugged in and the gen setting on the tailgate. Never even thought about hooking up a driven ground. (well, I did think about it, but decided not to). Never seen anybody drive a ground and hook it up before they started the gen. Used a portable Ohnan at work for a few years and there was no procedure for grounding it.

So here it is in a nutshell, who drives the ground and hooks it up each time?

[dznf0g]

I am no electrician, but over on the honda generator forum, the consensus is no ground stake required.

[TG Twinkie]

Your generator is not like the utility company's electrical grid, which is grounded at the source. Both the neutral and ground connection at the power source are grounded.
The neutral in your trailer should not be grounded.
Now to the generator.
The generator is considered an isolated (or floating) power source. The only way you would get a shock from the power produced by the generator is if you get between the hot leg and the neutral.
If the neutral is grounded in your trailer there is a risk that you could get shocked if you get between the hot side and the skin of the trailer.
I am sure there will be different opinions on this subject.

[dznf0g]

I just asked our new Honda Rep commercial member to start a thread on the subject relative to their products, both just sitting on the ground and running in a truck bed. Stay tuned?

[Bill M.]

never even thought about there being a Honda generator forum. Thanks. Will give that a look.

[SteveH]

When the trailer is plugged into the generator, the two grounds, and neutrals are tied together via the cord. No other grounding is needed.

[TBRich]

We have never grounded our Honda 2000w generators...neither running 1 nor 2 in parallel...(though when running 2 in parallel - Companion and a regular model - there is a connection between the ground screws of both generators...

[hissilver]

If you have installed a electrical systems monitor in your trailer and then attached a generator you will receive a "open ground"message and the generated electricity will be blocked. The ESM protects the trailer's electrical systems against power surges, brownouts, etc. You must bypass this protection system if you want to use generated power. These systems sell for $300 and up, but might be worth it depending on where you hook up to electricity.

[Soyboy]

Over on RV.net (same as Good Sam,Trailer Life etc.) this question has come up quite often over the years.

It goes back and forth everytime.

The results:

The experts say yes.

The experts say no.

Me: my Yamaha sits on the tailgate, I don't ground it.

My empirical evidence is that besides my years of using generators, also tons of service trucks, fire engines, big Prevost buses etc. etc. have generators, I've never seen one where they hammered a 6' (or whatever depth is "required") stake in the ground.

My safety rule, avoid running it when wet.

Just sayin'

[Protagonist]

This sort of thing is why safety professionals call their profession "risk management" these days.

Is there a risk if you don't ground your generator? Yes.
Is it a big risk? No, but keep reading.
Do you have to ground your generator? No. But if you don't ground it when the owner's manual says to ground it, don't expect your heirs to sue the generator manufacturer if you get electrocuted.

Fair warning, I'm about to get "preachy" again, as some other Forum members have (rightfully) chastised me in the past. If that bothers you, stop reading now…

I've investigated a couple of fatalities for the Corps of Engineers during the course of my career. No electrocutions, however. One thing that I learned in my accident investigation training is that there is never just one cause for any accident; there are always at least two. Either an unsafe condition combined with an unsafe act, or two unsafe acts that work together.

In this case, not grounding the generator is an unsafe act. As long as there is no other unsafe act or unsafe condition to go along with that, no one will get hurt.

But, if you run the generator ungrounded in a rainstorm, that's an unsafe act as well, and the two unsafe acts together can cause someone to be hurt. Or, if the generator develops a problem, such as damaged insulation on a wire that causes it to leak current to the frame, that's an unsafe condition, which combined with the previous unsafe act of not grounding the generator, can get someone hurt.

We're all adults here, and none of you work for me, so I can't tell you what you can or can't do. All I can do is explain the risks— as I see them— and let you decide for yourselves. Again, the risk is small if you don't ground your generator, as long as the generator is in good working order and you don't run it under conditions it wasn't made for. The rest is up to you.

[Soyboy]

Protagonist: First off this is not a flame, attack etc. I am just curious, do you ground your generator, if so, what do you do (this assumes you use a genny). I am really just looking for info, not in any way trying to argue.

Thanks for the post, it was interesting.

[Protagonist]

Originally Posted by Soyboy

Protagonist: First off this is not a flame, attack etc. I am just curious, do you ground your generator, if so, what do you do (this assumes you use a genny). I am really just looking for info, not in any way trying to argue.

Thanks for the post, it was interesting.

You're welcome. I don't take it as a flame or attack. Everybody needs honest inquiry in order to get a reality check. Even me!

My generator is permanently installed in my RV, and so is grounded to the AC ground bus in the RV. No ground rod required, as indicated in an earlier post.

My dad sometimes uses portable generators at his work (as well as portable electric welding machines). He grounds them, without fail. He never used to, until minor current leakage short-circuited his pacemaker and damn near killed him. Current ran from his hand where he grabbed the frame to his knees where he was kneeling on the ground, so the electrical path went right through his heart.

For those who want "official" guidance, here's what OSHA has to say on the subject. The fact sheet is written not for construction workers, but for those who have a generator for hurricane-related power outages. With hurricane season fast approaching, it seems timely…

http://www.osha.gov/OshDoc/data_Hurr..._generator.pdf

Interestingly, even OSHA says you don't always have to ground a generator, as long as the generator, and everything plugged into the generator, is bonded to the generator's frame. Only problem is, how can you tell? Owner's manuals are written idiot-simple and don't usually include wiring schematics. For a built-in generator like mine, the AC ground bus serves the purpose, but for portables…

And for those who want further technical reading, here is what the RVIA (Recreation Vehicle Industry Association) says about generators…

http://www.rvst.org/RVIA_Textbooks/Generators.pdf

Fair warning, it's dry reading.

[bredlo]

Originally Posted by Bill M.

never even thought about there being a Honda generator forum. Thanks. Will give that a look.

I'm with you - why would there need to be any other forum than this one?

[Soyboy]

Protagonist: Another question, again, not arguing, just asking and trying to understand (after years of trying to).

How is having a generator mounted in an RV different than using an external one?That is in the sense of grounding. I would assume with an RV and an internally mounted generator it would have something to do with the chassis of the genny being directly connected to the chassis of the vehicle (bonded?). But if there was some sort of insulation failure, couldn't the RV chassis become hot and then cause a shock hazard if one touched the vehicle and "earth" at the same time? If that is the case, then shouldn't that vehicle be grounded to "earth" just like a portable?

I just can't seem to get my mind around this whole floating ground thing. Does the fact that it is a floating ground and that the vehicle and the generator are "directly" connected, chassis to chassis eliminate the possibility of a vehicle to "earth" shock hazard. If that's true, I guess the hazard with a portable generator hooked to an RV, on a tailgate or on the ground is that the chassis of the two (gen and vehicle) are not bonded? They are only connected by the neutral and hot wires? But what about the "ground wire, I assume that is connected/bonded to the chassis of the portable generator so, then wouldn't the ground wire in the trailer also be connected to the trailer chassis, and that in turn created a bond between the vehicle and generator (as long as the ground was good). Of course maybe that is what we are protecting....the circumstance where, for some reason, the ground goes away.

Maybe I am asking too much to be explained on a forum, but if you could take a stab at it that might help this blockhead understand.

Thanks

[dznf0g]

Originally Posted by bredlo

I'm with you - why would there need to be any other forum than this one?

I'll warn you though, they're not as nice to one another as we are over here!

[dznf0g]

Soyboy, you're asking the same questions I have, and I think a lot of folks have. I don't get it either.

[Protagonist]

Originally Posted by dznf0g

Soyboy, you're asking the same questions I have, and I think a lot of folks have. I don't get it either.

I don't think anybody has all the answers. I may end up confusing myself if this keeps up… The important point to remember in all this is, you want to make sure the current never flows through a human body. It can flow wherever else it likes, as long as it's not through you or your loved ones.

Originally Posted by Soyboy

How is having a generator mounted in an RV different than using an external one?That is in the sense of grounding. I would assume with an RV and an internally mounted generator it would have something to do with the chassis of the genny being directly connected to the chassis of the vehicle (bonded?). But if there was some sort of insulation failure, couldn't the RV chassis become hot and then cause a shock hazard if one touched the vehicle and "earth" at the same time? If that is the case, then shouldn't that vehicle be grounded to "earth" just like a portable?

Because of the bonding, the chassis is the point of lowest common electrical potential. Current flows from higher electrical potential to lower leelctrical potential. You could energize the chassis in the case of current leakage, but as long as you're already in the RV, your own body is not part of the circuit. Now, if a plug-in device malfunctions, and you're holding that device, the leaking current tries to go from the device to the chassis, through you. That's why we have GFCI.

Does the fact that it is a floating ground and that the vehicle and the generator are "directly" connected, chassis to chassis eliminate the possibility of a vehicle to "earth" shock hazard.

Yes. As long as the generator is bonded to the chassis, any current leakage from the generator stays within the generator/trailer system; it doesn't go anywhere else. It's different when you're connected to shore power, but I won't explain the diference here; that will just make a confusing issue worse.

If that's true, I guess the hazard with a portable generator hooked to an RV, on a tailgate or on the ground is that the chassis of the two (gen and vehicle) are not bonded?

Trailer and generator are bonded through the umbilical's ground wire. As long as the trailer itself is not grounded to earth anywhere, the generator doesn't need to be, either. Even OSHA says that.

They are only connected by the neutral and hot wires?

Not quite sure what you mean by this one.

Even if you hitch the truck to the trailer, the truck does not share the trailer's ground bus. Current leakage from the generator may not go through the ground wire in the umbilical; it may go through the generator's frame and energize the truck; depends on just where the leakage occurs.

If it energizes the truck, it can energize you when you touch the truck.

But what about the "ground wire, I assume that is connected/bonded to the chassis of the portable generator so, then wouldn't the ground wire in the trailer also be connected to the trailer chassis, and that in turn created a bond between the vehicle and generator (as long as the ground was good).

Truck and trailer DC systems are bonded together by hitching up the trailer to the truck, but not the AC systems; the truck is still isolated from the rest of the AC system, until and unless current leakage from the generator energizes it.

Of course maybe that is what we are protecting....the circumstance where, for some reason, the ground goes away.

Not so much where the ground goes away, but where there's damage that causes the ground to be somewhere it's not designed to be. And in all cases, what we're protecting is human life, by making sure no one accidentally becomes a conductor in an electrical circuit.

Does this help, or make things worse?

[dznf0g]

Sorta....till I start thinking about it again!

[Soyboy]

Thanks Pro: gotta run now (going camping this weekend)...I might hit you up with a few more fine points later!

[wahoonc]

As a safety professional in the construction field I will weigh in too...it depends.

Our COMPANY policy is you ground all generators.

OSHA basically says "Ask MOM" MOM being the Manufacturer's Owners Manual.

We have about 30 generators in the field at any given time. I have done an exhaustive review of ALL the owner's manuals. With a few notable exceptions of older units none of the them require grounding unless required by local code. I have worked on projects where they had to be grounded by a licensed electrician, other projects we could ground our own, on others yet no one cared what you did.

Personally I ground mine if at all possible to minimize risk.

Aaron