[W2CRA] More on Grounding: Parts and References

[Bill Powell]

Some more on grounding - where to find parts and what NOT to do.

Yep - Copper is expensive and will continue to be costly for some time to come.
Copper flashing is available online from several sources at about $0.07 per square inch.  You can use copper flashing as thin as 3 oz if you back it up.  Take a look at www.acehardwareoutlet.com for starters.  Also browse the "dusty" part of an OLD hardware store.  You might luck out and find an OLD roll hidden back in a corner, still marked with it's $12 price.
Also check out garage sales (or your own garage or basement) for unused copper tubing / pipe.
Whatever you do, do NOT be tempted to "recycle" copper from an "abandoned" facility.  It's NOT worth your life.

Aluminum...
At less than a penny per sq in it's a potential bargain - IF you are VERY carefully in it's application.

Professionally installed ground systems exclusively use copper and make connections via exothermic welding (Cadweld), insuring a solid mechanical and electrical connection that is  corrosion-free.  

You don't get the same "deal" with aluminum.  Connecting to or joining aluminum is troublesome at best and damn near impossible if you aren't up to the task.  Aluminum also corrodes and it's corrosion products are non-conductors at best and can act as rectifiers (diodes) in the worst case.  And the worst case is VERY easy to come by if you are careless or sloppy in connecting aluminum to other metals.  Aluminum is as bad as galvanized when it comes to cathodic reactivity.


One thing I forgot to mention in the last message....
As I mentioned, the surge shunt (and BIG current) side of things wants thick, heavy, wide (and expensive) bare copper conductors connected to lots of ground rods.

The potential equalizing side, on the other hand, should NEVER be carrying any current and is there (mostly) to tie things together; equalize potential difference. You do NOT need #2 (or even #6 except where code requires) wire if NO significant current flow is ever expected and IF your exterior ground system is up to snuff AND you have a true SPG.  All heavier and wider buys you here is a better RF ground and slightly less impedance shack ground.
Yes, I use copper sheet under my equipment and along the wall behind but I bought it over 10 years ago when it was cheap.

You CAN use aluminum flashing here IF you take care to make both good (proper) mechanical and electrical connections.  Refer to the handbook.


References:
QST
	http://www.arrl.org/tis/info/lightning.html

Polyphaser: 
	Tech Notes: http://www.polyphaser.com/technical_notes.aspx
	Book: The "grounds" for lightning and EMP protection" (Out Of Print)
	by Block, Roger R.
	Published in 1993, PolyPhaser Corp. ([Gardnerville, Nevada?]) 

Web
	http://lightning-protection-institute.com/lightning-protect.htm

	http://www.wrblock.com/Papers/technical_paper_home_page.htm

	http://www.patentstorm.us/patents/6754060/description.html

	http://www.superb.org/Tools/Tech/paper/paper-g3/paper-g3.htm

	http://www.hamradio-badarc.co.uk/project/earthproj1.htm
	BAD example: Uses galvanized hardware to connect buried copper straps!!!

And, finally...
Guess what it's doing outside right now???

Bill (ZAP!) WB1GOT