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Joined: Jul 2004
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G
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The last time I went through this exercise I looked at a few sites for portable generators (Honda etc) and they all said the ground and neutral were NOT bonded?
If this is a generator sitting out in the woods, supplying cord and plug connected loads, how does bonding the neutral give you any protection? In fact it is better to not have the neutral grounded. This is essentually the same principle as using an isolation transformer.


Greg Fretwell
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Darryl Offline OP
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gfretwell wrote: "The last time I went through this exercise I looked at a few sites for portable generators (Honda etc) and they all said the ground and neutral were NOT bonded?
If this is a generator sitting out in the woods, supplying cord and plug connected loads, how does bonding the neutral give you any protection? In fact it is better to not have the neutral grounded. This is essentually the same principle as using an isolation transformer."

I WOULD BELIEVE THAT THE WAY YOU COULD GET HURT WITHOUT THE BOND IS BY GETTING HOOKED UP BETWEEN THE HOT AND NEUTRAL ON THE PORTABLE GEN... WITHOUT THE BOND, YOU ARE THE GROUND. IF YOU THINK THERE IS NO HARM FROM THE ISOLATED NEUTRAL ON HONDA PRODUCTS THEN WHY DOES EVERY OTHER GEN COMPANY BOND THEIR NEUTRAL AT THE GEN???? ARE THEY WRONG???

I'M TRYING TO SEE SOME CONSISTENCY OF OPINION AND FACT HERE AND I DON'T SEE ANY!!

[This message has been edited by Darryl (edited 01-17-2005).]

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G
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http://members.aol.com/gfretwell/honda.jpg

From the Honda EN3500 owner's manual

BTW if you get "hooked up" between the hot and neutral you are not "the ground", you are the "load".
The safety in isolation is because you do not complete a path if you are grounded and touch EITHER of the current carrying conductors.


Greg Fretwell
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Darryl Offline OP
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G,
You're right, not between the Neutral and ground but between the neutral and gen frame you would complete a path that would not be dangerous if the neutral was bonded... In the Honda case with the neutral isolated, you would get a shock between neutral and ground or frame of gen...

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G
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If the frame is not bonded to either current carrying conductor what is the path for current?

Perhaps you should go to article 250 and look at the reason we bond a service.


Greg Fretwell
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Darryl Offline OP
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"gfretwell If the frame is not bonded to either current carrying conductor what is the path for current?
Perhaps you should go to article 250 and look at the reason we bond a service."

the path is hot to load to neutral to you to frame or ground... In your line of thinking why is ANY generator bonded???

Joined: Nov 2000
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R
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George,
Quote
Hence the bonding jumper talked about in 250 for services is not applicable to generators. I'm not quite sure how youn size it.
Look at 250.30(A)(1).
Don


Don(resqcapt19)
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G
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Thanks Don, missed that one. Interesting enough though, the size is very close to 12.5%. In fact I've heard it stated from the podium that T. 250.66 is based on 12.5%. When you do the math it's pretty close. That's what I like about this forum, what one of us misses the other one catches.
George


George Little
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"The path is hot to load to neutral to you to frame or ground... In your line of thinking why is ANY generator bonded???"

How does ground or frame get in the fault path if the windings are not tied to either?

The reason we ground things on a utility service is because the utility grounds their end and provides that path.
There is no reason to ground one side of the winding on a portable generator. In fact you make it more dangerous when you do.
Do you understand the concept of an isolation transformer?
A portable generator is the same deal. If the output of the generator is not grounded you can safely touch either leg and not have a path to ground. (bird on a wire)


Greg Fretwell
Joined: Nov 2000
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R
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Quote
There is no reason to ground one side of the winding on a portable generator. In fact you make it more dangerous when you do.
There is a code reason to bond the generator neutral to the frame. 250.20(B), 250.26 and 250.34(C).
Don


Don(resqcapt19)
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