[TowerTalk] Idea Hamshack

[Jim Lux]

----- Original Message -----
From: "Thomas Miller" <ac5tm at bellsouth.net>
To: "Jim Lux" <jimlux at earthlink.net>
Sent: Monday, March 31, 2003 7:20 PM
Subject: Re: [TowerTalk] Idea Hamshack


> All grounds must also be connected together to the electrical ground to
> follow NEC.  NEC allows much smaller wire than good lightning protection
> protection should have because it is more for safety/fault than for RF or
> lightning grounding.

But NEC is reallly addressing the safety ground, not coax ground, which can
(and might) be different.  I've just been going through the IEEE Emerald
Book (IEEE std 1100) parsing it out, and it has much stuff on signal
grounding vs safety grounding vs lightning grounding, etc.

>From a lightning standpoint, you're probably best keeping it totally
separate (Emerald book points out that resistance and current carrying
capacity isn't as much a deal as low inductance), and then running a single
bond wire from the lightning ground to the safety ground to meet NEC. Keep
the lightning impulse away from the power line (and RF).

Also, for the "tower" and "shack" issue, each would need it's own lightning
system.  A separate bonding wire would connect the two, although it's not
clear whether that would be needed.