On 22 Sep 2009 23:19:40 GMT, Ed
wrote:
QUESTION: Are aluminum ground systems becoming common? Are they
reliable, even after absorbing some heavy strikes? Any other comments?
Ed K7AAT on the Oregon Coast
I've never seen any that use aluminum wire. Everything I've seen and
what little I've done was copper wire for both mountain top and home
grounding.
The National Fire Protection Association (NFPA) has guidelines such
things. See NFPA 780 "Standard For Installation Of Lightning
Protection Systems 2004". It describes protection for people,
building, and property from lightning damage.
http://www.atmo.arizona.edu/students/courselinks/spring07/atmo589/articles/NFPA_780_2004.pdf
1.1MByte PDF. Several sections mention aluminum use.
Googling merrily...
http://everything2.com/title/aluminum+wire
The only problem you have to consider is that you cannot
allow the wire to enter the structure because exploding
aluminum can cause a fire.
http://electrical.about.com/od/electricalsafety/a/lightningprotectionlightningrods.htm
The underground connection to the lightning protection system must
be made with copper wire because underground connections should not
be made with aluminum wire. Aluminum wire will corrode when placed
in the ground. The National Electrical Code requires the aluminum
wire connection be at least 18 inches above the ground [NEC Section
250.64(A)] with a bi-metal splice. This connects to an eight-foot
copper ground rod at least two feet from th home's exterior wall.
There must be a minimum of two ground rods installed to the system
on opposite ends of the home, with one near the service entrance
ground rod so it can be bonded to this ground rod. This ensures
that there is a common ground between all ground rods. This should
make the connecting copper wire length between the ground rod and
aluminum cable approximately four feet long. Place the ground rods
diagonally on either end of the house, not exceeding 100 feet
between the two ground rods. If this distance is exceeded,
additional ground rods must be added to ensure proper grounding.
http://www.glenmartin.com/catalog/lightning.htm
They use copper wire, but the lightning rod points are aluminum.
http://www.lightningrodparts.com/faq.html
(13) Will Aluminum Wire/Cable and Rods work as well as Copper?
It should as long as the installation rules are followed.
Certainly Copper is a better conductor than aluminum but
the Aluminum cable is larger than the copper therefore making
up for aluminum's lesser conductivity.
(24) BASIC INSTALLATION DETAILS:
No Structure shall have less than 2 ground rods (Aluminum wire
should not be underground)
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558