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Old 05-24-2008, 08:29 AM   #16
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Temporary Genrator Ground


I mean a ground rod alone does NOT ground anything in so far as a safety ground that trips breakers under fault current. It does NOT "create" a ground for a circuit.

If you stick a ground rod in the ground, and touch 120v to it, all you will do is electrify the ground and bring up worms.

IF that rod is bonded to the service the breaker will trip.

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Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.
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Old 05-26-2008, 04:06 PM   #17
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Temporary Genrator Ground


Portable generators should NOT have ground rods connected to them.

This is what I recently read to clear things up in my mind...

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

Ground rods are for high voltage events...ain't nothin like that in your case.

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Old 06-07-2008, 01:56 PM   #18
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Temporary Genrator Ground


Ok so I spoke with my employer regarding the ground rods and proper grounding of the generator, and informed him that the 3 shallow rods bonded together is not allowable by the NEC code. Told him that a ground rod is not required for cord-and-plug connected equipment (which is mostly what is being used with this generator). I'd assume that spider boxes that connect to the generator via 50amp multi-pin twistlock cables is still considered "cord-and-plug" connected.

He then told me that he talked to a local electrician/inspector who said that 3 rods in a triangle pattern at a depth of 4 feet each was acceptable, actually it sounded like it was preferred. Since driving an 8 foot rod into the ground is pretty difficult to remove, most people leave it in place and the inspector would rather see the shallow rods rather than rods being left in place. Which makes sense in that regard, especially with this being a temporary situation. This is apparently local to our area; which would explain the ground rod setup I originally posted about in the first place.

Just as an informational bit, this is a tow-behind 60kW generator that has 3 50amp twistlock connectors (for use with the spider boxes) and 3 20amp gfi outlets mounted on the front panel, and on the side is a high current tap connection. The generator is made by Baldor.

Thanks for all your input to this topic!
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Old 06-07-2008, 05:57 PM   #19
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Temporary Genrator Ground


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Originally Posted by theatretch85 View Post
I'd assume that spider boxes that connect to the generator via 50amp multi-pin twistlock cables is still considered "cord-and-plug" connected.
That is correct

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He then told me that he talked to a local electrician/inspector who said that 3 rods in a triangle pattern at a depth of 4 feet each was acceptable
Well, seeing as you don't need ANY rods, I see no harm in doing what the "electrician/inspector" and your boss considers acceptable. Sometimes keeping everyone happy, without doing any harm, is the easiest way to go. Just be careful about the tripping hazard with the rods. Falling down tripping, not breaker tripping.
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Old 06-08-2008, 06:21 AM   #20
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Temporary Genrator Ground


It is hard to understand who knows what is correct about anything anymore.
All standby generators should be grounded using #6 solid copper wire and an 8-foot ground rod, which must be properly bonded to the electrical grounding system with approved clamp/connections to assure good electrical contact. Cover all generator openings with wire mesh to exclude rodent entry and potential damage.
Source http://www.aecc.com/ (
Arkansas Electric Cooperatives, Inc.)
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Old 06-08-2008, 08:51 AM   #21
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Temporary Genrator Ground


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It is hard to understand who knows what is correct about anything anymore.
All standby generators should be grounded using #6 solid copper wire and an 8-foot ground rod, which must be properly bonded to the electrical grounding system with approved clamp/connections to assure good electrical contact. Cover all generator openings with wire mesh to exclude rodent entry and potential damage.
Source http://www.aecc.com/ ( Arkansas Electric Cooperatives, Inc.)
Well, this is Arkansas!

No seriously Billy, I think that the distinction is in the second word, standby. My inlaws are from Arkansas and a lot of houses down there have supplemental, permanently-installed generators. In this instance, the generator should be grounded as it can become the electrical source for the dwelling and in this case, ground fault energy would want to return to the generator when it is on-line. Another big difference is the fact that these applications are NOT serving "cord and plug connected" loads.
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Old 06-08-2008, 10:14 AM   #22
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Temporary Genrator Ground


Just push your boss for plug and cord, instead of electrode design and or removal and be done with it. I am aware that cables and plugs are not cheap, but I sure would rather make the investment and never use electrodes again.
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Old 06-08-2008, 12:54 PM   #23
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Temporary Genrator Ground


Haha, one of the biggest loads we use on the hard-wired lugs is a 36 channel dimmer rack, that would be rather hard to convert to a "cord-and-plug" connected load.
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Old 06-08-2008, 02:52 PM   #24
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Quote:
Originally Posted by BillyD View Post
It is hard to understand who knows what is correct about anything anymore.
All standby generators should be grounded using #6 solid copper wire and an 8-foot ground rod, which must be properly bonded to the electrical grounding system with approved clamp/connections to assure good electrical contact. Cover all generator openings with wire mesh to exclude rodent entry and potential damage.
Source http://www.aecc.com/ (
Arkansas Electric Cooperatives, Inc.)
I completely agree with you here. But a standby generator is supplying a structure and is not portable. So in that case, it would most definitely require a grounding electrode system.
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Old 06-08-2008, 02:55 PM   #25
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Temporary Genrator Ground


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Haha, one of the biggest loads we use on the hard-wired lugs is a 36 channel dimmer rack, that would be rather hard to convert to a "cord-and-plug" connected load.
With hard wired lugs I believe you do need a grounding electrode system. What amperage and voltage is that load? Just curious.
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Old 06-08-2008, 05:30 PM   #26
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Each channel can handle 1200 watts each, though its typically only loaded at 600-750 watts per channel. So on the low side with 36 channels at 600 watts each its 180 amps total (90 amps per leg). At 750 watts per channel, its 225 amps total (112.5 amps per leg). According to the generator spec sheet, it has a capacity of 179 amps per leg in 120/240 mode. The generator automatically shuts down if the load is out of balance by more than 25%.

I believe it is the Baldor TS60T: http://www.baldor.com/products/generators/ts.asp
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Old 06-08-2008, 06:57 PM   #27
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Temporary Genrator Ground


In the instruction manuals for the Baldor rigs, it says: "WARNING: Be sure the system is properly grounded before applying power. Do not apply AC power
before you ensure that grounds are connected. Electrical shock can cause serious or fatal
injury. NEC requires that the frame and exposed conductive surfaces (metal parts) be connected to an approved earth ground. Local codes may also require proper grounding of generator systems."
I guess it does need to grounded then?
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Old 06-08-2008, 07:24 PM   #28
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Temporary Genrator Ground


http://www.nfpa.org/freecodes/free_a....asp?id=7008SB
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Old 06-09-2008, 09:52 AM   #29
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Temporary Genrator Ground


Quote:
Originally Posted by theatretch85 View Post
Haha, one of the biggest loads we use on the hard-wired lugs is a 36 channel dimmer rack, that would be rather hard to convert to a "cord-and-plug" connected load.
When I say plug and cord in this regard I am not referring to the usual plugs and cords you normal come across. Industrial grade plugs and recpts can be almost any size you need. If you only have one point of connection for the output then I agree this is probably not an option. But if you have several outputs, I would be certain they could be used as plug and cord.
There are many large machines that are plug and cord. This would be the type I was referring too.
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Old 06-09-2008, 07:16 PM   #30
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Well the Dimmer rack has Cams on the back for the input, however the generator does not have cams, its only a hardwired high current output. I believe the wire is 2/0 stranded copper for each of the 4 conductors to the dimmer rack. My guess is that if the generator had cams that would still not qualify as "plug and cord" with 4 separate connections? For a load to be considered "plug-and-cord" does it just need to have all of the wires contained in one plug? Haha, anyone know where to find a 4 pin plug capable of say 250 amps @240 volts and capable of accepting 2/0 stranded copper?

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