[Elecraft] I need some grounding-strap guidance, if'n you please

Wes Stewart n7ws at yahoo.com
Tue Sep 1 11:50:41 EDT 2009


--- On Tue, 9/1/09, Jim Brown <jim at audiosystemsgroup.com> wrote:
The "coil" at the base of the pole sounds like lazy 
electricians to me. 

Nope, it's SOP in the utility business.  And no end of trouble in the RFI "business".

My rural electric co-op uses aluminum wire for the above-ground part of the grounding system, either for cost, copper theft, or both reasons.

They also love staples and drive them at too frequent intervals up the pole to secure the ground wire.  Unfortunately, a green pole shrinks considerably in the 6% RH typical here in the summer and the ground wire then arcs to the loose staple.  So the fix is to drive them deeper.  I've then seen the wire cut when the pole expands again when the RH increases.  This nearly undetectable break then arcs and generates lots of intermittent noise.

The same thing happens at the crimp they use to connect the aluminum to the copper; that's a physically weak point that can break and cause the same trouble.

This used to be a much worse problem before they replaced thousands of epoxy insulators that crazed in the Arizona sunshine and had 100's of mA of leakage current; a lot of it flowing in these ground wires.  They actually had some insulators catch fire from the heating.

Regards,

Wes  N7WS





      


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