alt.energy.homepower

On Thu, 06 Sep 2007 15:19:07 -0000, philkryder < @ > wrote:

>On Sep 6, 7:40 am, Neon John wrote:
>> On Thu, 06 Sep 2007 04:02:51 -0000, philkryder < ...@ > wrote:
>> >John -
>> >does this mean that you disagree with the more recent GFI models with
>> >Bonded Neutral?
>> >Your points make a lot of sense (at least to me).
>>
>> Are you talking about the neutral fault detection that trips if the neutral and
>> ground become connected aft of the GFI?
>>
>> Yeah, I disagree with that. I'm not really sure what problem this "feature" is
>> alleged to solve. All I've seen it do is cause more nuisance trips.


>John - Yes, I think that is it - though the exact details of the new
>GFI machines aren't completely clear to me.

The way it works is this. There is a second toroidal inductor around the hot and
neutral lines. It is driven by the 60 hz signal and is the primary of a transformer.
The neutral is the one turn secondary. Ignore the hot lead for this discussion.

The neutral and ground are bonded together at the breaker. If they get connected
together aft of the GFI then a complete circuit is formed, neutral->ground->breaker
ground->breaker neutral->neutral. Current flows in this loop, induced by the second
toroid. The main sensing toroid detects this as imbalance current and trips the GFI.

It's hard to imagine any credible (not fictitious products of some safety nazi's
imagination) scenario where connecting the neutral and ground together causes any
hazard. I'm not sure what they were thinking (scratch that, they weren't thinking)
when they came up with this "feature".

>
>Could you describe specifically how you ground a generator at a
>jobsite or somewhere it will only be for a day or two?
>How do you verify the quality of the ground?
>Do you connect it directly to the ground lug on the gen head? or do
>you also connect to the generator frame?

I don't ground it. I leave the neutral floating. If the generator has the neutral
and green wire connected internally then I separate it. The green wires and the
third pins are still there but they don't do anything.

In the rare event that some other consideration (such as noise on amateur radio
equipment being powered by the generator) requires earth grounding then I connect the
earth ground (green wire) and the generator chassis (via the grounding lug that most
of 'em have) to a known good earth ground, usually a ground rod.

John
--
John De Armond
See my website for my current email address

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