Generator Grounding Revisited

[John T]

I wasn't surprised I couldn't explain the basics of when and when NOT to ground a portable genset to "some" non professional electricians or non electrical techs or lay persons, but hey I tried my best as I always do in order I might save someones life.

I was going most on memory and didn't dig in my library to cite OSHA or NEC regulations but it turns out I GOT IT RIGHT or at least I agree with OSHA and the NEC if that counts lol

I tried to explain how the NEC (and saw how OSHA did the same, see below) indicated you DO NOT drive a ground rod and attach to your portable genset if its powering tools fed from an onboard receptacle and tried to explain how THAT IS ACTUALLY HAZARDOUS TO DO SO AND COULD GET YOU ELECTROCUTED.


LOW AND BEHOLD AND SHUCKY DERN OSHA Regulation 29 CFR 1926 and the NEC state:

"In other words, a ground rod is NOT required and in fact may create a hazard" HMMMMMMMMM SOUNDS LIKE WHAT I SAID

It goes on further to state "why eliminate the ground rod? because the ground rod potentially introduces an electrocution hazard" HMMMMMMMMMM SOUNDS LIKE WHAT I SAID


So if you don't believe me no problem,,,,,,,,,but if you don't believe OSHA or don't believe the panel of NEC electrical experts or Mike Holt TAKE IT UP WITH THEM NOT ME I know what's right, I spent my life studying and practicing electrical engineering and safety. If you can prove to OSHA and the NEC why you are smarter then they are and you are right and they are wrong, then give it a shot and if you can then I will eat crow and humble pie lol

The trouble a non electrician or lay person would have trouble understanding is how there are times EARTH GROUNDING SHOULD BE USED AND OTHER TIMES (as above) ITS NOT PER OSHA AND THE NEC (NOT me mind you). Does the genny have a floating or bonded Neutral???????????? Is the Genny configured as a Separately Derived Source" or not???????????? Is the genny used in conjunction with a transfer switch and utility and if so how many poles is the transfer switch??????? Is the Neutral being switched??????????????

BOTTOM LINE WHICH MAY SAVE A LIFE if you don't believe me or dont believe OSHA or don't believe the NEC and know more then allllllllll of them, are you willing to go ahead and drive that ground rod and let your barefoot grandchild stand on wet ground and operate the electric tools fed by the genset????????????? I BEG YOU PLEASE PLEASE DO NOTTTTTTTTTT

So to anyone who still proclaims you MUST use a ground rod to make a genset safe, please please read all the below and look at Mike Holts explanation of how a ground rod cant stop electrocution and read OSHA and the NEC and consider changing your mind which could save your life.

NOTE 1) Do NOT feel bad or insecure or that youre a bad person if you dont understand the reasons when and when NOT to use a ground rod!!!!!!! Even engineers and electricians who are educated and experienced in the field can struggle with this.

NOTE 2) If on a job OSHA or an NEC Inspector levied a fine due to no ground rod THAT MAY BE BECAUSE THAT EXACT SITUATION OR CONFIGURATION OR WIRING SCHEME OR TRANSFER SWITCH OR NETURAL GROUND BOND OR NO BOND OR FLOATING NEUTRAL ETC ETC DICTATED IT

Hope this helps, I sure have tried so read what OSHA and the NEC and Mike Holt all have to say before you assume or Billy Bob or Bubba told you or by golly you always did it that way or you saw OSHA issue a fine (sure it was exact same situation?? willing to bet your life on that???) BEFORE YOU MAKE IT A BLANKET PRACTICE TO ALWAYSSSSSSSSSS DRIVE THAT GENERATOR GROUND ROD BECAUSE DOING SO COULD GET YOU KILLED.

A) OSHA AND NEC GENERATOR GROUNDING: http://www.oshaprofessor.com/Portable%20Generators%20and%20OSHA%20Construction%20Standards%203-05.pdf

B) Mike Holts explanation of Grounding doesn't prevent electrocution: https://www.youtube.com/watch?v=KlKiWk4Bb5Y


God bless and keep you all safe. As always feel free to do as you see fit and safest regardless if OSHA and the NEC say different, its your life you're risking.

John T Retired AC Power Distribution Electrical Engineer
OSHA AND NEC GENERATOR GROUNDING

 

[Janicholson]

The independent genset is like a tiny electrical "universe". When used with no grounding rod, it sees your tools as an extension of that universe. GFIC and other safety devices (like spark interrupt) respond to that "universe". Putting a grounding rod in the earth near the use point extends the "universe" but has no return conductor. Nasty. Jim

 

[Steve@Advance]

Just as confused as I ever was...

It still amazes me that 480v generators, running carnival equipment, in the rain, with SO cord laying on the ground, with clueless people walking on it... And never even heard of anyone getting shocked!

I do prefer to give them plenty of respect though!

 

[John T]

Hey Professor, youre an electrical person, glad you understand this stuff.

John T

 

[JD Seller]

JohnT you had better tell several generator manufactures to change their owner manuals then. I understand what you talking about now. The generator would not have return circuit if it is NOT grounded and is insulated from any earth ground. I get what your talking about.

However I assumed that the operators manual with the generator in question would be a better thing to go off of over internet forum recommendations. I have an old Onan 4000 watt generator that I know is over 40 years old. I down loaded the manual a few years ago. It tells you to ground the generator. I have a three year old Honda 7000 watt generator and it also says to ground it when used in wet conditions.

I also talked to my BIL an he told me the local OSHA inspectors will fine you and shut you down if they see a generator not grounded on a job site. He has paid the fine and has 4-5 crews out on jobs daily.

So you can see the confusion????

Also it is condescending to talk about "barefoot" Kids using power tools run off a generator. Maybe it is a "Southern" thing but my kids and grand kids wear shoes and appropriate clothing when working.

I still think you should use a GOOD cord with the ground pins in them at all times and Forget using any portable electrical devise outside if it is wet/raining.

 

[John T]

Steve, as I'm sure you understand, there's a good chance their 480 volt is Three Phase Three Wire UNGROUNDED Delta which has no reference nor any voltage with respect to mother earth ground so in theory you can stand barefoot on wet ground and grab any one leg and NOT be shocked. Of course due to inductive and capacitive coupling there can be voltage present relative to ground and could give you a tingle but its extreme lowwwwwwwwwww energy insufficient to pump 30 milliamps through your heart in theory at least IM STILL NOT TRYING IT LOL Today much 480 three phase is actually 480 Y 277 Volt Three Phase Four Wire GROUNDED NEUTRAL.

In the case of a non earth grounded portable genset (as OSHA and NEC recommends) its the same thing, with no bond to earth none of the wires to the tools have voltage relative to earth so you dont get shocked if you touch one UNLIKE if you drove a ground rod at the genny and bonded it to Neutral then the hot wires ARE 120 VAC ABOVE GROUND AND CAN KILL YOU IF TOUCHED.

Glad you get this stuff

John T

 

[John T]

Good to hear from you JD and glad you're starting to get this stuff lol hey it takes electricians years sometimes grrrrrrr

YES I understand the confusion, it took me years of education and in the field experience and dealing with Electricians and other Engineers and I still get cornfused lol esp since I'm so long retired from it

SURE Onan or any Genset instructs you to "ground" because that's the often used method of operation UNLESS its the case where it was used to power cord and plug tools fed from onboard receptacles OFTEN WHICH MANY GENSETS DO NOTTTTTTTTTTTTTT HAVE

In my RV with an ONAN it says to GROUND HOWEVERRRRRRRRRRRRRR CAN YOU SEE THATS NOT THE SAME AS DRICING A ROD INTO THE EARTH AND TRYING TO DRIVE AWAY LOL The more proper expanded definition might say connect to a GROUNDING ELECTRODE (Thats considered Grounding) but in that case the RV iron frame serves as the GROUNDING ELECTRODE. Its NEC or OSHA Grounded per the manual, but nottttttttttttt to mother earth. See the difference??????????????

In the OSHA and NEC specs I cited, the genset frame serves as the GROUNDING ELECTRODE however in the same case it says DO NOT CONNECT TO A DRIVEN GROUND ROD AS ITS AN ELECTROCUTION HAZARD

If you notice, the instructions usually say something like GROUND PER NEC and they DO NOT go into if the Neutral is floated or bonded or if its tied to a transfer switch and if so how many poles and if the Neutral is switched or not?????????? ALL THAT MATTERS BUT IF THE INSTRUCTIONS SAY GROUND PER NEC THEY ARE OFF THE HOOK LOL

ALSO the term "grounding" isn't all that simple, you have to read the Code and OSHA, theres earth grounding and theres the Neutral to Ground BONDING and theres the EQUIPMENT GROUND. If you took the time to watch alllllllll of Mike Holts Videos some of those differences will come to you.

ALSO being trained as BOTH an Engineer and an Attorney I'm familiar with Technical and Instruction writing and terms, I bet they are covered if they say GROUND PER THE NEC

AGAIN THE OSHA INSPECTOR WHO LEVIES FINES FOR NOT GROUNDING hopefully you can now begin to see HOW IT DEPENDS on the wiring and genset and configuration and floating or bonding on and on and on READ THE OSHA SPECS I ATATCHED theres not much doubt about when NOT to ground...........

I AGREE USE GOOD 3 WIRE CORDS

FUN chatting and trying to explain this to you and others but really its not hardly possible unless a person is well trained and experienced in this complex subject BUT HEY GIVE ME AN A FOR EFFORT LOL You sure do help others on here which I appreciate and respect

God Bless JD and take care

John T

 

[Geo-TH,In]

John T,
I know power companies use mother earth as a conductor, but why couldn't they just run another wire and isolate the electricity form mother earth? Aren't some RV generators 220v, 3 wire, no grounding? My take, only an uneducated wild guess discussed with Bubba many times when we are drinking BPR, is lightning must have some place to go when it strikes electric wires. Which means send it to ground where it headed before it has a chance to dance all over inside your house and blow the load center off the wall. Geo.

 

[JMOR]

(quoted from post at 07:40:09 06/13/16) John T,
I know power companies use mother earth as a conductor, but why couldn't they just run another wire and isolate the electricity form mother earth? Aren't some RV generators 220v, 3 wire, no grounding? My take, only an uneducated wild guess discussed with Bubba many times when we are drinking BPR, is lightning must have some place to go when it strikes electric wires. Which means send it to ground where it headed before it has a chance to dance all over inside your house and blow the load center off the wall. Geo.

ood luck in maintaining isolation for a network of miles, hundreds of miles, thousands of miles.

 

[John T]

George, GREAT QUESTION but I cant answer it here, its much more complex grrrrrrrrrrrr

The Utility DOES NOT use mother earth as a normal routine "conductor" in the ordinary sense, they have the aerial or buried wires for that. The purpose of mother earth grounding is for lightning and surge protection and to stabilize the entire grid at one common low voltage reference MOTHER EARTH, in a limited sense you might call that a "conductor" (for surge and lightning at least) but I'm sure you see the difference, you're pretty sharp in this electrical business.

On the grids HV Primary, at every few poles the Neutral is mother earth grounded,,,,,,,,On the LV Secondary at the utility transformer the Neutral is mother earth grounded,,,,,,,,,,,At the incoming service to your home Neutral is again mother earth grounded ALL TO KEEP THE GRID AT EARTH REFERENCE AND PROTECT AGAINT SURGES AND LIGHTNING STRIKES

YOUR RV QUESTION Butttttttt George, they are indeed GROUNDED as NEC and OSHA required just NOT to mother earth !!!!!

An RV Generator is wired and configured as a "Separately Derived Source" and requires its Neutral be bonded to a GROUNDING ELECTRODE. Since it wouldnt be too handy to drive down the road attached to an earth ground rod, other permissible Grounding Electrodes (such a iron frame buildings structural steel) suffice. On the RV when youre on genny power and NOT wired to the utility there still needs to be "single point grounding" and Neutral bonding so the RV frame suffices. Even on utility power in a steel frame building the steel can serve as a Grounding Electrode.

In accordance with OSHA and the NEC (NOT me remember) if you use power tools fed from onboard genny receptacles correctly configured and wired YOU DO NOT EARTH GROUND BECAUSE IT CAN INTRODUCE AN ELECTROCUTION HAZARD

BUT LAY PERSONS (heck even some trained electricians and professionals lol) HAVE A HARD TIME UNDERSTANDING THAT ONE AS MY RESPONSES BELOW INDICATE ACTUALLY AS THE OSHA ARTICLE DESCRIBES, EARTH GROUNDING COULD GET YOU KILLED, BUT SOME NON TRAINED GENTS WILL STILL DO IT grrrrrrrrrrrrrrrrrrrrrrr

Take care George, sorry I cant teach here what it takes years of study to understand BUT I DO TRY !!!

John T

 

[KCTractors]

John T, I have a question for you? You sound like you know what you are talking about, I mean that in a good way. I have two Honda 2000 generators, hooked up with the parallel cables, going to the RV with a 30 AMP cord. I have the generators sitting on a wood platform so if it rains, they are not setting in water. The RV is setting usually on wood pads, so no ground there. I was told to ground the gen-sets, so it sounds like I shouldn't be doing that. So I should be not grounding the gen-sets or the RV, is that right? Thanks for your knowledge John T.

 

[Billy Shafer]

Hey John T. Will you now explain stray voltage to everyone. I have had this fight so many times over the years. I just gave up and installed it the way the inspector wanted. Then left the customer with some suggestions.Had one hell of a time. Trying to explain why you shouldn't install. A computer controlled transfer switch. In the same room as a radio transmitter.

 

[John T]

1) I can answer your question IFFFFFFFFFFF I know if your genset has a FLOATING Neutral or not???

2) I suspect the Honda is FLOATING IE it has no Neutral to Frame/Case/Ground terminal BOND.

3) Like most gentlemen out there who aren't electricians or techs or engineers (and even many of them lol), they don't understand the differences and confuse grounding with N-G bonding and EARTH grounding which is completely separate. EARTH grounding is totally separate from N-G bonding, and EARTH grounding is not required by the NEC or OSHA for an RV or portable generator (kind of hard to drive down the road wired to a ground rod isn't it). Don't take my word for it, SEE MY OSHA POST BELOW which some just don't want to or refuse to believe I'm afraid, their being smarter then NEC and OSHA or for whatever reason is beyond me??????????

4) SOOOOOOOO HERES THE DEAL since its for RV use and is NOT going to be tied to a utility or utility transfer switch
YOU DO NOTTTTTTTTTTTTTTTTTT NEED TO DRIVE ANY EARTH GROUND FOR THE HONDA That's what OSHA says, that's what the NEC says
even if some lay gents and Billy Bob and Bubba insist otherwise. BUT THAT DONT MEAN THE MANUAL DONT SAY TO "GROUND" IT
because there are situations (depends on how its used) where N is bonded to case/frame and all that is attached to a ground
rod. As long as it says "ground" per the NEC they are covered. When a company makes a genset they cant know how it will be
used so they may Float the Neutral or they may not EITHER is correct in certain situations yet they still have to say Ground
per the NEC and in some cases an earth ground rod is required while in others its NOT and even a hazard SEE MY OSHA POST WHY

HOWEVER 1) THATS NOTTTTTTTTTTTTTTTTTTTTTT TO SAY ITS STILL NOT "GROUNDED" per the NEC because the term grounded can be
confused with Neutral to Ground BONDING. Its just NOT EARTH grounded to a rod driven down into mother earth

HOWEVER 2) If your RV does NOT have a fancy EMS monitor system it can still work and power whatever you have plugged into
it EVEN IF IT HAS A FLOATING NEUTRAL

HOWEVER 3) If your RV DOES HAVE an EMS and is indeed a floating Neutral as I suspect, THE EMS WILL PROB THROW AN ERROR CODE

HOWEVER 4) If it is floating and iffffff it trips an error code on an EMS THERE IS A FIX

HERES MY ADVICE A) Ifffffffffff the Honda has a Floating Neutral I would bond it to any available steel frame (if it has any) AND ALSO to the GROUND terminal in that 3 wire outlet. That's often done in the RV world using a pigtail SEE THE LINK BELOW. That simply involves a small jumper wire connecting N and G together in a plug plugged into one of the outlets or else inside an outlet itself.

B) DO NOT I REPEAT DO NOTTTTTTTTTTT DRIVE AN EARTH GROUND ROD AS OSHA SAYS THAT CAN CREATE AN ELECTROCUTION
HAZARD

NOW LISTEN CAREFULLY there are reasons why a new Genset may have a Floating Neutral (they ship millions out that way and they aren't stupid) and there are reasons when and where the N should be bonded to G and there are times when earth grounding MUST also used and any genset manual will say ground per the NEC BUT IT MAKES A DIFFERENCE DEPENDING ON ITS USE AND IF THERES A UTILITY OR TRANSFER SWITCH INVOLVED AND HOW MANY POLES AND IF NEUTRAL IS SWITCHED. I understand those differences but its nearly impossible to teach non electricians all this grrrrrrrrrrrrrrrrrr

SUMMARY I would NOT drive a ground rod,,,,,,,,,,If the Honda has a Floating Neutral and you use it as a portable or RV generator and do NOT ever tie it to a transfer switch or utility I WOULD MYSELF CREATE A NEUTRAL TO GROUND BOND. If theres no EMS it can still work floating however.

HELPFUL LINKS IF YOU DONT BELIEVE ME

1) Neutral to Ground Bonding in RV's by Jack Mayer:

https://docs.google.com/document/d/1X0A0bD4D-0n-GJmtEKK_ls5mYFdupgmqA1Xtb06JDLM/edit?pli=1

2) Generator Neutral ground Bonding:

http://noshockzone.org/generator-ground-neutral-bonding/

3) I have a PDF listing makes and models of Generators showing if they have a Floating Neutral or not but I cant get the URL link to it SORRY

Whewwwwwwwwww I'm tired

John T

 

[John T]

Hey Billy, good to hear from you, as an old Generator man I'm sure you get all this. I don't know if I have the smarts or energy left to get into stray voltages, I pretty well left everything I had above lol and RF energy just isn't my thing. Computer digital control which may switch due to extreme low voltage differences can be affected by RF energy floating in the air which is why if its enclosed in say a "faraday shield" that is all earth single point grounded errors may be preventable. I just don't know much about RF to explain it even to myself let alone others lol

I have a PDF file but cant find the URL which shows makes and models of Gensets and which have a floating and which have a bonded Neutral. I have about give up trying to explain to non sparkies who know more the OSHA or the NEC all the differences and when and where one system is used or when earth grounding is required or when its a hazard grrrrrrrrr

Sorry no help on this one Billy

John T

 

[Janicholson]

I will make a short answer. All voltage comes from a pile of electrons going where there are some missing. or less of a pile. The stray voltagtes found on farms come from several sources. They could come from a galvanized water tank and a piece of steel in the same muddy barn yard through galvanic reactions/corrosion. They could come from leaking electricty from grounded wires with no GFCI. They could come from induction into conductors from power lines or magnetic devices like open transformers or motors/generators. If the voltage is high enough to be felt by you, it will be radical to the lips of a farm animal. Jim

 

[Billy Shafer]

But when you try and explain that to most people. You get the deer in the headlight look.

 

[Billy Shafer]

Funny thing about that transfer switch. After not believing me or the site tech. The owner called in a expert from the transmitter OEM. My flies down comes to the site. Opens the door and says where is the shield. Owner just about had a fit.

 

[Geo-TH,In]

John T,
Bubba and I will have to drink and think on it. Bubba's first electrical job was his last, He burnt the BIL's trailer to the ground, mother earth's ground. Geo.

 

[mj]

Pretty complicated, makes me believe the old saw: 'If God had meant us to work with electrons, He would have made them big enough to see!'. :roll:

 

[Janicholson]

In Canada there are Kilometers and Kilometers of single wire medium voltage (3500 to 4000) lines powering rural farms and homes. Jim
Info.