Grounding a generator

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I do not know exactly what the code says, but I do know what makes sense from a safety perspective. The neutrals of all circuits should be connected to ground at ONLY one place - in your main service panel. There must be no grounding of neutrals in sub panels. Ranges etc. connected to sub panel circuts should use a 4 pin connector (hot, hot, neutral, ground).
The ground wire from your main panel may be connected to multiple grounds and it's best if these are close together. Two grounding rods are frequently used for a lower resistance ground path and better reliability.
Do not ever use a pipe as a ground. The water supply line may be PVC or may be changed to PVC at some time in the future and you would have no ground.
Since a good ground is so important, use the gauge wire required by code or larger, protect it where required and never allow a splice in it. Use only the best quality U/L approved grounding clamps and be sure all contacting surfaces are clean and tight.
All of this applies to your generator too. For best safety, if your generator is outside, it should be physically close to your system ground.
If the code requires anything less, it should be changed.
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Our transfer switch switches both hots and the neutral.
Steve Spence Dir., Green Trust http://www.green-trust.org
toller wrote:

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turning the mains breaker off and the generator breaker on. The neutral doesn't have a switch on it that I saw.
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No, I don't touch the breaker box. I don't have a separate breaker for the generator. I'm on inverter until I turn on the generator. the auto transfer switch then switches the loads from inverter to generator. There are two relays in the box, one switches the two hots, the other switches the neutral. when the gen is shut off, it switches the loads back to inverter.
you can see a picture of it at http://www.green-trust.org/wiki/index.php?title=Our_Solar_PV_System
Steve Spence Dir., Green Trust http://www.green-trust.org
toller wrote:

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>> Our transfer switch switches both hots and the neutral.

Some "alternate energy" systems are installed as separately derived sources so they would use transfer equipment that switches the neutral. (perhaps as part of protection for transients when the system is not connected to the building ground) On the other hand most "generator" transfer switches for portable generators will not switch the neutral since the standard on portable generators is an isolated ground. If used as a stand alone generator on a job site there is no advantage to grounding the neutral, in fact it adds a hazard. Fixed in place, pad mount generators can go either way. They will have a grounding strap in the wiring compartment that you connect or disconnect, depending on how you are installing them. This whole deal can get pretty complicated to describe but the end objective is to only have one point where ground and neutral is connected, no matter how the system is switched. When I am inspecting a complex system I have to draw it out sometimes to sort out what is going on.
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toller wrote:

Depends on the design of the transfer switch, I have one outside that is set up for three phase and has four poles on the switch body. Dave
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On 27 Dec 2004 17:35:58 GMT, Ignoramus24153

I believe like any sub-panel, the ground must run back to the main panel. Sorry that I can't remember what article this is in, maybe someone else can help with that.
later,
tom @ www.Stuff4Free.biz
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On Mon, 27 Dec 2004 18:01:23 -0500, snipped-for-privacy@intertainia.com wrote:

conductor is not switched, the generator equipment should be seperately grounded. The NEC section on seperately derived systems is not one I've spent a great deal of time with, however. In practice I have a hard time understanding what problem could arise from connecting the ground.
Dan
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Ignoramus24153 wrote:

This may help things..
http://www.cat.com/cda/components/securedFile/displaySecuredFileServletJSP?fileId 865&languageId=7
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