I'll take a stabe at this. First off, go to the Polyphaser and ICE websites
and thoroughly read up on what they recommend for second floor shack grounding.
You've grounded the shields but you've not grounded the center conductor. The
only way to do that is to install lightning arrestors which will protect both
sides of the coax. Also, the long run from the existing shield ground up to
the shack entrance may be long enough for energy to be induced in that section
alone. I'd say that Poly and ICE will recommend that you install arrestors up
at the shack entrance panel and then run a very low resistance/impedance ground
wire (wide copper strap) down to the house perimeter ground. You didn't say
how the existing shield ground is bonded to the AC entrance ground. If that is
not low resistance/impedance then it may be useless. You may want to beef up
that connection wire and/or add ground rods along it's length. Finally
depending on if your house wiring is in conduit or not you'll want to install
either whole house surge protection (former) or surge protectors at the shack
equipment (latter) to protect against energy induced in
to the house wiring. All of this also applies to CATV, network, rotator
control, and other wiring that connects to the equipment. Finally if the tower
ground system is not too far away, connect it to the house perimeter ground
system. How is the tower ground constructed? Phil KB9CRY
-------------- Original message --------------
> At 05:43 AM 8/2/2005, Tom Rauch wrote:
> >....You not only had a very poor tower ground, it sounds like
> >the entrance panel was never bonded to the power mains
> >entrance ground! If we don't bond the entrance panel to the
> >utility ground it is a big problem (and goes against the
> >national electric code).
> >As you painfully found out, ground rods do next to nothing
> >for establishing a good ground. A poorly grounded radio
> >entrance panel that isn't bonded to the utility entrance is
> >also a big problem.
> OK - Question. My aluminum entrance panel is in a second-floor
> window. The hardline (CATV) comes out of the ground (conduit) alongside
> the house, and flexible coax runs from there across a porch roof, maybe 50
> feet to the shack window. Where the hardline comes out of the conduit, I
> have grounded the shield to the same ground rod as the AC service.
> I disconnect everything at the entry panel but don't usually disconnect
> equipment from the house AC. With close hits I have had three instances
> when I have had arcs from the center conductor of the barrels in the entry
> panel to the shell, and thence to ground -- it's pretty startling, but
> aside from a little soot, no visible damage.
> Two years ago I took a hit on the top of my tower, about 200 feet from the
> house. No radio gear was damaged. I lost 2 computers and a phone
> answering machine due (I think) to induced voltage on the house Ethernet
> wiring, and of course everything electrical on the tower proper (2
> rotators, an RCS-4V and a Stackmatch).
> Have I done about all I can, given my compromise shack location? Would it
> make sense to plug grounding plugs into the barrel connectors, to "assist"
> the strike voltage in finding its way to ground?
> 73, Pete N4ZR
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
> and ask for Sherman, W2FLA.
> TowerTalk mailing list
Phil - KB9CRY
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
TowerTalk mailing list