Tony,
My PE (who is a ham and subscribes to this reflector) specified "...2/0 copper
or equivalent..." with at least one conductor and ground electrode per tower
leg.
The rest of my ground system uses smaller conductors.
Consider the current in a direct or nearby strike may be upwards of 2KA. You
don't want the conductor(s) to act like fuse(s). Refer to a chart for the
FUSING current of wire.
As others have stated, aluminum rots easily. Use copper only.
vy 73,
Bryan WA7PRC
>________________________________
>
>Date: Wed, 18 Jun 2014 14:38:23 -0400
>From: Tony K1KP
>
>A question for the esteemed masses:
>
>What is the advisability of using aluminum conductors for lightning
>grounds? For example, I have a ground system consisting of #6 stranded
>copper and multiple ground rods. I would like to add on to the system,
>and I have a bunch of #2 aluminum available (old line drop stuff). Can
>that be used?
>
>1. Would it handle the current? Or would it vaporize?
>2. I know there are issues about Cu-AL connections which would have to
>be addressed.
>
>What Say?
>
>-Tony, K1KP
>
>------------------------------
>Date: Wed, 18 Jun 2014 17:17:30 -0400
>From: Roger K8RI
>
>On 6/18/2014 2:38 PM, Tony K1KP wrote:
>> A question for the esteemed masses:
>>
>> What is the advisability of using aluminum conductors for lightning
>> grounds? For example, I have a ground system consisting of #6 stranded
>> copper and multiple ground rods. I would like to add on to the system,
>> and I have a bunch of #2 aluminum available (old line drop stuff). Can
>> that be used?
>
>You'll probably get a lot of answers, but my take is:
>
>Depends on the PH of your soil and moisture content.
>Al is quite active chemically and corrodes
rapidly.
>>
>> 1. Would it handle the current? Or would it vaporize?
>
>It is used from the meter to the panel quite often. When we built my
>shop and installed an underground service (both were 200A) the run from
>the meters to the panels was Al, although several sizes larger than Cu.
>That and it required re tightening the connectors over two years as the
>Al cold flows under heavy pressure.
>
>I don't consider bare Al suitable for direct burial.
>
>> 2. I know there are issues about Cu-AL connections which would have to
>> be addressed.
>>
>> What Say?
>>
>> -Tony, K1KP
>
>------------------------------
>
>Date: Wed, 18 Jun 2014 16:33:00 -0700
>From: Ray N6VR
>
>I agree, Al is not good direct buried.
>
>Al underground will deteriorate/disappear quickly, perhaps less than a year
>depending on the soil PH and moisture content.
>
>Ray,
>N6VR
>
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