[AT] : Ice Storm

charlie hill chill8 at suddenlink.net
Sun Dec 16 17:57:01 PST 2007


Henry,  I've already admitted that I'm no electrician but I have to question 
one thing you are saying.  How is a ground fault interupter going to work if 
it's not connected to a ground?  If you are using any sort of tool that has 
a three prong plug and you don't have an earth ground on the generator YOU 
are going to become the ground if something goes wrong inside the tool.

Charlie
----- Original Message ----- 
From: "Henry Miller" <hank at millerfarm.com>
To: <at at lists.antique-tractor.com>
Sent: Saturday, December 15, 2007 2:14 AM
Subject: Re: [AT] : Ice Storm


> On Friday 14 December 2007 12:45:15 charlie hill wrote:
>> Mike you are probably 90% ok since you are grounded through the transfer
>> switch.  I was primarily talking about the units that are sitting on
>> trailers and connected via drop cords.  If you plug something into the 
>> drop
>> cord in that application  you have no ground.
>>
>> I'm not qualified to talk about your situation because I'm not an
>> electrician by any means BUT my friend said something about a ground
>> potential difference between the ground in the house and the generator 
>> unit
>> and said that the unit it's self should be grounded.  Maybe someone else
>> can explain that.  Like I said, I don't really know other than what I was
>> told. Electrical stuff is one of my very weak points.
>
> Grounds are VERY complex.   They seem simple, but they are the most 
> complex,
> most dangerous part of an electrical system.
>
> Summery for those who don't want to know the whys:  When using a generator 
> as
> portable power, plug into a GFCI outlet and ignore the ground connections 
> (if
> your generators doesn't have a GFCI get one installed).   When using a
> generator to power your house, the house provides the ground, any earth
> connection at the generator could be a DEADLY second ground!
>
> Long explanation follows:
>
> The safest system has NO ground connection at all, and perfect wiring. 
> If
> there is no ground connection you can safely grab a live wire. 
> Unfortunately
> things are not that simple, it only takes one mouse (every house has mice) 
> in
> the walls to turn your perfect wiring into wires with problems.   One 
> problem
> isn't too big a deal, as you shouldn't be touching the wires anyway. 
> When
> there is a second problem it can burn your house down!  Fuses won't 
> protect
> you because these problems don't have to be big enough to blow a fuse to 
> burn
> the house down.    So fire code requires (and rightly so) that one wire 
> has a
> good connection direct to ground.  The hope (and this mostly works out) is
> that if there is a problem, the good ground will make it more likely that 
> a
> fuse will blow.   There are many different cases of a bad ground and 
> several
> electrical problems burning a house down, so make sure your house has a 
> good
> ground.
>
> Note that I said A good ground, as in singular!   Strangely enough, two
> grounds can kill you just by walking in the wrong place.   (Sometimes a 
> house
> will have several different ground rods, but these are carefully connected 
> so
> they act as one ground)  So if your have your generator wired to a 
> transfer
> switch in your house you should not have a ground connection on the
> generator, as your house is already grounded.   If your generator has a
> ground point (and all non-plastic generators should), it should be 
> connected
> not to the earth, but to the ground connection in the house.   (By rights
> your generator should have a switch so you can select if generator is
> grounded at the house or in the generator, but I've never seen a generator
> with this, most likely because the switch wouldn't be connected right
> anyway.)
>
> For generators on a trailer (meaning not used to power a house) the 
> situation
> is different.   The rules are simple: Grounds are for fire protection, and
> not human protection.  GFCIs are for human protection.   So for your 
> outdoor
> use make sure you only plug things into GFCI outlets (Don't forget to test
> all GFCIs monthly by hitting the test button and making sure all outlets 
> you
> think should be protected really turned off).   The GFCI will take care of
> everything you want a ground for, and avoid the hassle of getting a good
> ground connection.
>
> If you can't use a GFCI outlet, double insulated tools and good cords 
> (inspect
> them as you unroll them, and get rid of any that are getting frayed) are 
> good
> enough.  Equipment that has a ground connection is a risk when run from a
> generator.
>
> Note, if you have a pacemaker things are more complex yet, because they 
> are
> affected by tiny currents that you wouldn't notice.   I recommend you 
> check
> with your doctor and pacemaker manufacture to see what the rules are, 
> before
> you use any generator or welder.
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