Grounding a generator

My reading of the pertinent section tells me that if the grounded 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

Actually I don't think it does. You change from mains to generator by turning the mains breaker off and the generator breaker on. The neutral doesn't have a switch on it that I saw.

...

Exactly

Probably the best grounding electrode AKA a Ufer ground (H.George Ufer invented it)

Bronze. May look like brass or copper at a quick glance

Solid.

Even better

Wayne

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.

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

Get a grounding rod and bang it into the earth, then, use the appropriate connector to fasten 1/4" solid flexible copper to ; fasten the other end to the generators ground connector. Thats exactly what im about to do to my portable generator.

That would be for the neutral. What they don't permit is a second isolated ground: See

I recently spoke to a professional electrician who confided that although prohibited by the NEC, multiple hot-neutral bonds are quite common. He has seen the question raised in professional meetings, and the answers were always sketchy.

It seems that some electronic equipment is affected by noise impressed onto ground, but the problem is overrated.

Hot-neutral bonds?????????????????

Any time turn something on you get a hot-neutral bond, though usually a high resistance one. Second hand information from a "professional electrician"... geez, when I see some of the work done in the past on my house by professional; my 23a water heater was run with #12 on a 30a breaker, a multiwire circuit was all on the same leg, etc.

A bond implies no -middle man- sort of load between two conductors.

The gentleman meant to say ground to neutral connections.

The guy doing your wiring should have been fired. A number twelve wire suitable for house wiring is usually rated for 20 amps. Heating loads have to use no more than 80 percent of the wire 'ampacity.

So, his number 12 was good for only 16 amps in this situation.

a 30 amp (#10) wire would have barely met the legal requirements (.8 X

Oops!!!! :)

I wonder if the water heater woudl be considered a 'continous load' like a houses heating, but it does make sense even without the derating, #12 shouldn't be used on a 30am breaker.

I'm guessing it was a typo.

later,

tom @

I have done that many times, it's why I'm always buying new screwdrivers. Quite a show when it happens :-( Dave

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.

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.