[TowerTalk] Copper pipeing

[Nick Pair]

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.
   
  73
  Nick 
  WB7PEK

 		
---------------------------------
Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls.  Great rates starting at 1¢/min.