grounding generator?

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  #1  
Old 09-07-04, 10:08 AM
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grounding generator?

I plan on using my generator at some motocycle races. We will be powering my friends trailer (air, frig, tv, etc). I wanted to know how to ground it. It has a nut to connect to ground wire. I went to home depot. They only have 8 ft long rod. I was hoping to use something smaller. They have 3 ft long steel (or steel with zinc plating) and aluminum rods. I was thinking of buying one of these in 1/2 inch and putting a tip on with grinder and then connect with some wire. Is this OK? Am I going overboard? I know that most don't even ground their generators but the instructions do say to do so. It is a 10hp troy built rated at 5550 watts (8550 peak)

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Bill
 
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Old 09-07-04, 06:16 PM
hex2k1
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Hammerash,


I think you might be going overboard, according to the nec 250.34 (A) the frame of portable generator shall not be required to be grounded and shall be permitted to serve as the grounding electrode for a system supplied by the generator. so basically as long as you have cord and plug connected equipment (tv frig etc..) connected to the receptecles mounted on the generator frame, and you have a bond from non current carrying metal parts of equipment, and receptecles of generator to the frame of generator you are code compliant. the only time you need to pound a ground rod in is if your using portable generator to supply fixed wiring systems (hard wired).
 
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Old 09-07-04, 07:23 PM
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Since you will be plugging in a fixed wiring system (the trailer), you will need the ground rod. 8' of the rod must be driven and in contact with the earth.
 
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Old 09-07-04, 07:33 PM
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generator grounding

Now there are two widely different replies. To clarify something, the "trailer" that I am talking about is a towed trailer with a single plug that will be plugged into my generator. So I don't know if this qualifies as being "hard wired"? Any other thoughts on this? Also of note, the generator has rubber tires so only a 2 inch area of frame opposite the tires is in contact with the earth.

Thanks
bill
 
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Old 09-07-04, 11:56 PM
hex2k1
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I agree with Handyron if your trailer has a fixed wiring system you will need the ground rod. since you didnt specify that your trailer had (fixed wiring system) i assumed it didnt in my reply. another thing you cant use aluminum electrodes as a grounding electrode. as far as the 2 inch area that is in contact with the earth i dont think it helps anything in either case. i beleive what theyre trying to achieve is to get fault current to travel in the direction of the supply instead of the cord and plug connected equipment.
 
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Old 09-08-04, 04:50 AM
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I am of a different opinion. I would consider this closer to a vehicle mounted generator. I wouldn't consider the trailer having a fixed wiring system, yet.
The best course of action IMO is to bond the frame of the trailer to the genset frame. It being on the ground is no different than it sitting in the trailer.
Think of it this way, if it were on the ground, feeding a fixed wiring system, it would need an 8'x5/8" ground rod.
If it were at the exact same location but on/in a trailer bolted down it would be fine with just that.
I say a #8 or #10 solid copper bond from the gen to the trailer frame is an adequate solution.

I'll tell you this. I go to A LOT of drag races and several motocross races a year and NO ONE bonds generators to trailers. I don't have a generator since I don't need a battery charger for my car and I have a small inverter for my laptop so I mooch 120 volts off my buddies.
I have never seen a ground rod, nor a trailer bond. This is definitely not to say it's right, and a bond is a good idea.
The generator is bonded to it's frame and the trailer should be bonded to it's grounding system, but an extra bond is a safety measure.
 
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Old 09-08-04, 06:10 AM
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Thanks all

I have never seen anyone else at an event like this ground the generator either. But the manufacturer does recommend grounding it in the instructions. Last year during the hurricane (Isabel), I grounded it to my water lines. But carrying around an 8ft long rod for when you are away from home is more than a little inconvienent and you risk breaking underground pipes or buried electical lines by pounding it in unmarked ground. Plus I think it would be a little difficult to remove an 8ft long rod. Thats why I thought about using a 3 ft rod originally. I know I am probably being anal about this.

Speedy Pete, you said you wouldn't consider it a fixed wired system, yet. Not sure what you mean by that? This is a camper type trailer. Maybe 20ft long or so. It has a built in frig, furnace, tv, a couple of beds. When he is camping, he just plugs in one 30amp plug into the supplied outlets at the site. Hope that clarifies everything. Probably go with bonding gen to trailer but I don't think that the trailer gets grounded in any way. Is this still OK

Bill
 
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