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[TowerTalk] Copper pipeing

Subject: [TowerTalk] Copper pipeing
From: Nick Pair <>
Date: Wed, 12 Jul 2006 23:24:35 -0700 (PDT)
List-post: <>
If you are finding pinholes in the copper piping near or touching a iron 
rebar/mesh it is dissimilar metals doing the deed. The alkalinity of the 
concrete that drives the iron-copper cell. All copper systems in my neck of the 
woods have to have these junctions prevented.Especially now that we have a lot 
of steel studs used in commercial work. (Here in NW WA we export trees and 
import steel to make studs. Whats wrong with this picture?) Up here we have a 
lot of galvanized water piping in 70's and 80"s houses. They rust pinholes from 
the inside out in about 15 years or so. Surprisingly the earlier ones aren't as 
bad. All interior piping must be grounded to service for electrical safety.
  Rebar is only allowed to be used as a grounding electrode when fully encased 
in concrete. Otherwise you must use a 3/4 or large galvanized pipe 10 feet long 
or a galvanized ground rod 5/8 solid or better or copper/copper-clad ground 
rod. Rods are to be 8 foot or longer. Currently 2 are considered minimum but 
local jurisdictions may require more. Of course the approved connectors must be 
used, especially with the dissimilar metal connections.
  The NEC wants to have all your grounding tied together but doesn't address 
your radial system with it's insulated wire.
  I'm glad to see that all are not forgetting the rather large dc component of 
lightning and the effects of plasma if the strike chooses to jump even the 
smallest gap. The plasma is such a different animal form dc and rf that it's 
parameters are still an unknown.

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