Ed wrote:
I am only interested in the long term reliability of an aluminum ground
system in comparison to the more common copper system. This is for
lightning suppression only, I am not addressing RF issues. I am wondering
if aluminum can handle the potential surge currents that copper can... and
how well does its ground conductivity work when buried, when compared to
copper.


For surge currents only, Al would need to be thicker than Cu of equal
handling capacity. If you are stressing things to the max, Al has a
lower melting point.

It would work for RF ground also. The oxide layer would not affect the
performance. Lots of us use insulated copper wire for ground radials.

Only concern I would have is that the electrical connections are
properly made. AL's talent for oxidizing has been a problem in the past
with house wiring.

- 73 de Mike N3LI -

"Michael Coslo" wrote in message
...
Ed wrote:
I am only interested in the long term reliability of an aluminum ground
system in comparison to the more common copper system. This is for
lightning suppression only, I am not addressing RF issues. I am
wondering if aluminum can handle the potential surge currents that copper
can... and how well does its ground conductivity work when buried, when
compared to copper.


For surge currents only, Al would need to be thicker than Cu of equal
handling capacity. If you are stressing things to the max, Al has a lower
melting point.

It would work for RF ground also. The oxide layer would not affect the
performance. Lots of us use insulated copper wire for ground radials.



The OP referred to a 'vault ground ring', not radials.

Furze is a major supplier of lightning protection products in the UK and
they don't favour aluminium for earth connections:
http://www.furse.com/elp/earprod.htm. I understand copper and
copper-plated-steel is still used for neutral earth connections by UK
electric power supply companies as well - the oxide layer on aluminium and
its alloys, if present, must have some value of breakdown voltage and
anything that elevates neutral above earth that can be avoided has to be a
bad thing.

Chris

In article ,
Michael Coslo wrote:

Only concern I would have is that the electrical connections are
properly made. AL's talent for oxidizing has been a problem in the past
with house wiring.

A good point.

The National Electric Code has some fairly specific requirements for
how grounding system connections must be made. Soldering is not
permitted, as the high temperatures which can occur at such
connections during a lighting strike can blow the soldered connection
apart. Strong mechanical connections, or welding (e.g. "CadWeld"
thermite-type welding) is required.

I just ran across the following:

http://www.homeinspector.org/resourc...-Grounding.pdf

It indicates that the NEC forbids the use of aluminum conductors for
grounding "where in direct contact with masonry or earth. Aluminum
conductors require 18 inches of clearance from earth." (NEC
paragraphs 250-91a and 250-92a are cited).

There's also a note on the citation: "ATJ note: we have field
reports of complete failure of uninsulated bare aluminum grounding
conductor wire when it was not properly protected from corrosion - for
example where left touching a masonry foundation wall."

It sounds to me as using aluminum wire as a lightning ground system
is a poor idea.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Below is good information, but only applies to electrical systems'
grounding... not commercial radio vault lightning ground systems. Also,
the aluminum system I came across certainly had crimp or other mechanical
bonding methods which avoids the connection issues discussed in the NEC.

I have no control or great concern on this, but was surprised to see
aluminum for my first time. I just wondered if it was common.

Ed K7AAT


..

The National Electric Code has some fairly specific requirements for
how grounding system connections must be made. Soldering is not
permitted, as the high temperatures which can occur at such
connections during a lighting strike can blow the soldered connection
apart. Strong mechanical connections, or welding (e.g. "CadWeld"
thermite-type welding) is required.

I just ran across the following:

http://www.homeinspector.org/resourc...lectrical-Grou
nding.pdf

It indicates that the NEC forbids the use of aluminum conductors for
grounding "where in direct contact with masonry or earth. Aluminum
conductors require 18 inches of clearance from earth." (NEC
paragraphs 250-91a and 250-92a are cited).

There's also a note on the citation: "ATJ note: we have field
reports of complete failure of uninsulated bare aluminum grounding
conductor wire when it was not properly protected from corrosion - for
example where left touching a masonry foundation wall."

It sounds to me as using aluminum wire as a lightning ground system
is a poor idea.

On Sep 24, 1:56*pm, Ed wrote:
* *Below is good information, *but only applies to electrical systems'
grounding... not commercial radio vault lightning ground systems. *Also,
the aluminum system I came across certainly had crimp or other mechanical
bonding methods which avoids the connection issues discussed in the NEC.

* *I have no control or great concern on this, but was surprised to see
aluminum for my first time. *I just wondered if it was common.

* *Ed * K7AAT

.

The National Electric Code has some fairly specific requirements for
how grounding system connections must be made. *Soldering is not
permitted, as the high temperatures which can occur at such
connections during a lighting strike can blow the soldered connection
apart. *Strong mechanical connections, or welding (e.g. "CadWeld"
thermite-type welding) is required.

I just ran across the following:

*http://www.homeinspector.org/resourc...lectrical-Grou
* nding.pdf

It indicates that the NEC forbids the use of aluminum conductors for
grounding "where in direct contact with masonry or earth. *Aluminum
conductors require 18 inches of clearance from earth." *(NEC
paragraphs 250-91a and 250-92a are cited).

There's also a note on the citation: *"ATJ note: *we have field
reports of complete failure of uninsulated bare aluminum grounding
conductor wire when it was not properly protected from corrosion - for
example where left touching a masonry foundation wall."

It sounds to me as using aluminum wire as a lightning ground system
is a poor idea.

The only time in my life that I saw aluminum corrosion was when I
spotted aluminum tubing sticking out of the ground at the house. It
just made a pile of aluminum dust!
I have no idea how a ground plane would work if the aluminum opened up
in time in different places, so sticking with copper seems the best
way to go. If I had a problem with radiation my mind would be pointing
at the aluminum every time so why the hassle?
You never know what state your ground is in these days because the
builders spread building garbage aound before they spread the grass !
Now we have acid rain to think about.

(Dave Platt) wrote in
:

In article ,
Michael Coslo wrote:

Only concern I would have is that the electrical connections are
properly made. AL's talent for oxidizing has been a problem in the
past with house wiring.

A good point.

The National Electric Code has some fairly specific requirements for
how grounding system connections must be made. Soldering is not
permitted, as the high temperatures which can occur at such
connections during a lighting strike can blow the soldered connection
apart.

I always laughed about this requirement, because if you have THAT much
energy present to do this, you're going to have much bigger problems than
that soldered joint.