grounding a portable generator?

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Old 08-23-05, 06:10 PM
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grounding a portable generator?

I know I discussed this before but am going on a trip again so wanted to try to clear things up. Using a Troy-Bilt portable generator to power a camping trailer. When I use it at home, I attach the ground to my water pipe. The instructions say to ground it when used. How do I ground it when camping? Buy a copper grounding rod and drive it into ground and attach to generator? If so, how far do I have to put it into ground? The generator is Portable-has rubber tires and the other side has a piece of metal that the generator rests on. The camper is not grounded as far as I know. My buddy doesn't do anything like put a rod in ground. Someone before said to just run wire from generator to camper? But if the camper isn't grounded what good does this do.

Also, do they make a connector to go from my generator L14-30 outlet to and RV connector? If we use the adapter my buddy has we have to plug the RV into one of the 20amp outlets from generator instead of the 30amp L14-30. Could i just buy male L14-30 plug and run the white, green wires and then pick one (either red or black) and run these from generator to a female RV plug and get 30amp 120volt

Bill
 
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Old 08-24-05, 09:08 AM
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Originally Posted by hammerash
Could i just buy male L14-30 plug and run the white, green wires and then pick one (either red or black) and run these from generator to a female RV plug and get 30amp 120volt
Yes, you can. Just be sure to use at least 10 gauge wire for the cord. This will create an unbalanced load on your generator though. Generators usually don't operate as well will that sort of imbalance, and may shorten the life of the generator.
 
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Old 08-24-05, 11:28 AM
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[QUOTE]
Originally Posted by hammerash
I know I discussed this before but am going on a trip again so wanted to try to clear things up. Using a Troy-Bilt portable generator to power a camping trailer. When I use it at home, I attach the ground to my water pipe. The instructions say to ground it when used. How do I ground it when camping? Buy a copper grounding rod and drive it into ground and attach to generator? If so, how far do I have to put it into ground? The generator is Portable-has rubber tires and the other side has a piece of metal that the generator rests on. The camper is not grounded as far as I know. My buddy doesn't do anything like put a rod in ground. Someone before said to just run wire from generator to camper? But if the camper isn't grounded what good does this do.
They key to determining if the generator needs to have a grounding electrode in a portable situation is whether or not the neutral is grounded to the case of the generator or not. Almost always if the generator has receptacles mounted on the frame for cord and plug equipment it will have the neutral grounded to the case. This requires a grounding electrode to limit surges, lightning, contact to higher voltage and limits the voltage to ground on conductive metal parts. If your manual says you have a grounded neutral to the case of the generator you need to drive a ground rod or other suitable grounding electode. You also must have a ground wire in the cord to the camper.
 
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Old 08-25-05, 10:09 AM
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You dont need a ground rod with cord and plug connected loads, if you are conecting this to premise wiring then you would connect it to the building grounds. What good would it do to pound a stake in the ground ? The ground wire in the cords will already elimnate any potential differences between the source and the connected equipment.
 
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Old 08-25-05, 11:24 AM
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grounding a portable generator?

There is a wire that runs from the generator winding case to the frame. This wing nut is where you then are to attach wire/ground. Here is what is written in the instruction manual regarding grounding:

The National Electrical Code requires that the frame and external electrically conductive parts of this generator be properly connected to an approved earth ground. Local electrical codes may also require proper grounding of the unit. For that purpose, a GROUNDING FASTENER is provided on the generator end (Figure 2).


Generally, connecting a No. 12 AWG (American Wire Gauge) stranded copper wire to the grounding fastener and to an earthódriven copper or brass grounding rod (electrode) provides adequate protection against electrical shock. Be careful to keep the grounding wire attached after connecting the stranded copper wire. However, local codes may vary widely. Consult with a local electrician for grounding requirements in your area.

Properly grounding the generator helps prevent electrical shock if a ground fault condition exists in the generator or in connected electrical devices, especially when the unit is equipped with a wheel kit Proper grounding also helps dissipate static electricity, which often builds up in ungrounded devices.

Bill
 
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Old 08-25-05, 11:35 AM
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Originally Posted by sberry27
You dont need a ground rod with cord and plug connected loads, if you are conecting this to premise wiring then you would connect it to the building grounds. What good would it do to pound a stake in the ground ? The ground wire in the cords will already elimnate any potential differences between the source and the connected equipment.
I disagree portable generators that have the neutral grounded to the frame and offer cord and plug receptacles are required to have a earth driven electrode connected to the grounding lug on the generator. This has nothing to do with clearing line to line faults, it is there to dissipate static build up, surges, lightning and contact with higher voltage lines.
This is a highly controversial subject and you wont find very many who agree and I cant say as I fully understand this....I did some research as a result of your querry.....take a look at these and see what you think pay particular attention to portable use and neutral grounded to case. Not connecting a portable generator to a dwellings premise wiring through a transfer switch.
http://www.guardiangenerators.com/PublicPDFs/0E0226.pdf

http://www.hondapowerequipment.com/G...f/31ZC2702.pdf

http://www.imsasafety.org/journal/marapr/ma5.htm
 

Last edited by Roger; 08-25-05 at 11:46 AM.
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Old 08-25-05, 12:20 PM
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portable generator grounding?

Confusing? So I guess I need to know if it has the neutral grounded. I have the wiring diagram and scanned it in as a jpeg but can't figure out how to send it? Also tried to import into word and then paste it in this reply but that didn't work? I am not sure how to interpret the drawing. Any way to submit it on here as attachment?

Thanks to all
Bill
 
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Old 08-25-05, 12:46 PM
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Almost all small units designed for cord and plug use have bonded neutral. Someone can correct me if I am wrong here but I think the only ones you would find that werre not would be large industrial units designed for connection to premise wiring. This is being way over thought here, the only use I can see for a ground rod would to be to ground the trailer for potential lightning strikes so the cord condustor wouldnt tend to carry strikes back to the genset,, in this case if you get a direct hit you would likely be screwed anyway. Dependig on the unit I think I would just adapt to a 20A outlet and if I needed more power then use another cord on an opposite outlet. How big is this unit, what model? Typically trailers with 30A 120v service have 2 breakers in a panel, one goes to AC unit and one to serve the rest of the trailer. If you are not running AC it wouldnt be able to use more than 20 anyway.
 
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Old 08-25-05, 01:17 PM
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I see your post now, and I look at one of the manuals. It doesnt quote code section and I dont feel like looking it up right now but there is a size somewhere in the code that talks about grounding. We had a LONG discussion on Hobart board with this. In these manuals they seem to imply that the rod has something to do with fault protection which leads me to believe that someones nephew is a tech writer for them. I understand static, that would be a possibility but how would a rod help with contact with other high voltage lines? Or surges, from what to what? Personally I would plug the thing in and be done with it. I think a guy is going to be in more danger of hitting an underground feeder with a groud stake or hurting himself with a hammer pounding it in that he would gain in saftey from doing it. The main saftey connection, the neutral to equipment bond for clearing faults is already done, other than that it would certainly be shaving some really fine hairs to improve this. In fact on Hobart we had some engineering input and they thought that under certain conditions a rod may increase hazzards by setting up a ground loop. I dont remember all the details as it was a while back, I think someone even got in tough with eginnering from Miller and they seemed to imply to ignore it, they put it this way,,, when they use their own gensets they dont do it. There are millions of these in use everyday, welding industry uses this setup constantly and we dont do it.
 
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Old 08-25-05, 02:05 PM
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I certainly am not going to be able to argue with what you have posted because I have never driven a ground rod when using a gen set on a job site.
Your right about the lightning was almost not going to say that but it is stated in the manufacturers instructions. Seems way out there as you say. It would appear as you point out that the manufacturers are just as confused as the public who buy the generators. You wont find me driving an 8 foot ground rod any time soon at every job site I'm working just to cover these concerns for these rather unusual circumstances. I did not mean to imply that at all. I was simply disagreeing on the premises of manufactuers instructions. I cant even remember in all my years ever seeing a ground rod driven for a portable generator at a job site. If you read that last posted link to the informational article you will see that it even states that the frame can act as the ground or the frame of the vehicle you mount it on can act as the ground. Then quickly it states....Caution... if neutral is bonded to frame it needs a ground rod. So go figure since every portable I've been around is neutral bonded.
 
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Old 08-26-05, 12:01 AM
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The generator is troy-bilt, 5550 watt. It has a 30amp L14-30 plug and 4 20amp plugs. Thanks to all that have responded. I decided to not drive a rod. I actually had mentioned to my buddy previously that I would be concerned about hitting something (water, electrical lines) if I did drive a rod and someone had same concern. I leave tomorrow morning for motorcycle races at VIR so will not be able to reply any more.

Thanks

Bill
 
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Old 06-18-10, 02:02 PM
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To ground or not to ground?

I am in agreement wtih most contractors regarding this issue. I have yet to see anyone ground a portable generator at a job site. With that said, I have studied electrical and electronics most of my life, and there are two things that will keep me from grounding a portable generator: 1.) The idea is that the neutral of the generator is grounded to the frame of the portable generator, and this same neutral is the neutral return path for the power being supplied to the building or the appliance. That being the case, It would appear to me that you would be inducing an additional ground loop and it's associated line losses. The Transfer switch will disconnect the incoming voltage source and neutral from the power line, but it won't interrup the existing main's ground to rod connection. 2.) I would also be concerned about driving a ground rod into unknown territory and risking rupturing a water line, gas line or electrocuting oneself by driving into an existing underground wire.
The generator manuals tell me that the reason they are suggesting an external ground is to prevent electrocution of the operator. If that is the case, and you really want to be safe, use an inductive type voltage sensor to ensure the frame isn't hot before you grab hold of it; or use rubber gloves when you shut the power down. That's my two cents for what it is worth.
 
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Old 09-02-10, 06:46 AM
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You can not be careful enough, but you cant be TOO CAREFUL.
Its no big deal to use a ground rod and it will be safer. I didnt ground a generator and the surge screwed up some electronics in the house. USE THE GROUND ROD.
 
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Old 09-02-10, 07:24 AM
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NEC 250.34 states:

250.34 Portable and Vehicle Mounted Generators

(A) Portable Generators. The frame of a portable generator shall not be required to be connected to a grounding electrode as defined in 250.52 for a system supplied by the generator under the following conditions:

1) The generator supplies only equipment mounted on the generator, cord and plug connected equipment through receptacles mounted on the generator, or both and

2) The normally non current carrying metal parts of the equipment and the equipment grounding conductor terminals of the receptacles are connected to the generator frame.
There is more that described vehicle mounted generators, but it sounds like the OP is talking about a small portable generator.

From the OP description it sounds like no ground rod is required.
 
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Old 09-02-10, 07:42 AM
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stake to the heart

The real hazard is when the rod hammering person is done with the portable genset and leaves the ground rod sticking out of the ground. THAT's the hazard here...
One could make a strong case that the system is safer if the genset is totally isolated from ground.
 
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