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Re: Lightning and neutral grounding



The National Electrical Code forbids grounding the neutral (grounded circuit
conductor in NEC speak) anywhere except at the service entrance.

>From the 1996 National Electrical Code and Handbook:


"On major reason the grounded circuit conductor is not permitted to be
grounded on the load side of the service ... is that, should the grounded
service conductor become disconnected at any point on the line side of the
ground, the equipment grounding conductor and all conductive parts connected
to it will carry the neutral current, raising the potential to ground of
exposed metal parts not normally intended to carry current.  This could
result in arcing in concealed spaces and could pose a severe shock hazard,
particularly if the path should be opened inadvertently by a workman"

The Code is also fairly specific about how to bond the antenna grounds to
the service entrance ground ... Article 810-21(f).  I urge you to check a
library or your building inspector for guidance.

Joe KM1P

----- Original Message -----
From: "Phil - KB9CRY" <kb9cry@attbi.com>
To: "Greg D." <ko6th_greg@hotmail.com>
Cc: <amsat-bb@AMSAT.Org>
Sent: Tuesday, March 11, 2003 6:11 AM
Subject: Re: [amsat-bb] Lightning and neutral grounding


> Greg, you have the basic concept correct that you need to tie your
> lightning arrestor ground rod to the electrical ground but do not do
> this inside the house.  This wire may have lots of voltage on it during
> an event and you don't want to start the house on fire.  You need to tie
> these two together outside of the house.  I've got the same problem as
> you in that the service entrance and the shack are on opposite sides of
> the house.  That's OK.  What I did was to lay a #4 bare solid wire and
> ran it from my single point ground around the perimeter of the house and
> tied it to the service entrance ground rod.  Use long radius bends
> around the corners of the house and make sure you do a good job of
> connecting the wire to the rods.  Be careful when working around the
> service entrance ground as the hot incoming wires may be exposed.  Check
> out the technical papers at the Polyphaser web site for more info.  You
> can also drive ground rods around the perimeter of the house and tie
> this wire to those to be really grounded.  Phil  KB9CRY
>
> Greg D. wrote:
>
> > Hi folks,
> >
> > So, I think I've got this straight, but just to be REALLY sure...
> >
> > The service entrance for our house is on the opposite side from
> > the shack.  It's a standard 220 service, which I believe is two
> > phases of 110, with the common (neutral) being grounded at the
> > entrance.  The two sides of the service are split randomly around
> > the house to balance the load, giving each plug 110v.  The Air
> > Conditioner and clothes dryer are wired across both hot leads,
> > for the full 220 voltage.
> >
> > On the opposite side of the house is the shack.  Each of the
> > coax cables coming down from the roof-mounted antennas goes
> > through a lightning arrestor.  All of the arrestors are mounted
> > in an electric service panel box and the whole thing (each
> > arrestor and the box itself) are grounded to a pair of 8' ground
> > rods spaced about 5' apart.  Leaving the arrestors, the coax
> > cables go through a hole in the wall into the shack and to the
> > rigs.  The rigs are plugged into the wall plug nearby for power.
> >
> > So the question:  I believe everything is done more-or-less
> > correctly, EXCEPT that I need to tie the neutral of the electrical
> > plug in the shack to the same grounded bar that the arrestors are
> > bolted to.  "Neutral" is "white wire" side of the plug.  (The hot
> > side is black, as in charcoal, which is what happens to your
> > finger if you touch it...).  I can't depend on the service entrance
> > ground to be at the same potential as the ham ground during a strike,
> > since they are too far apart.  The safety ground (green wire) is
> > left alone.  This means snaking a heavy wire from the lightning
> > arrestor mounting bar, into the wall, and over to the electrical
> > outlet box, and attaching it to the neurtal side of that wall plug.
> > I don't need any other sort of lightning arrestor on the power line,
> > other than a good "surge protector"; our electrical service has an
> > underground feed.
> >
> > Is this correct?
> >
> > Thanks,
> >
> > Greg  KO6TH
> >
> >
> > _________________________________________________________________
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> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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>
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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