On 4/3/19 1:24 PM, john@kk9a.com wrote:
Aluminum and copper are not real apart on the galvanic table. Stainless
steel and aluminum are a much worse combination. I would use conductive
grease such as Penetrox between the Array Solutions device and your
plate and simply bolt them together. I have copper and aluminum
connected together in my ground system and I have not seen any issues.
Not to mention millions of electrical connections in standard electrical
wiring. The ground/neutral bar in the circuit breaker box is usually
alumimum, and there's all those copper wires clamped in it. And, using
wire-nuts or crimped connections to join copper and aluminum wires.
The key thing is to avoid something where temperature cycling causes it
to loosen - you need enough clamping force that when they grow and
shrink, they stay together.
The bad thing about aluminum wiring in houses was the cost driven change
to steel terminal screws (from brass) at the same time as aluminum was
rolled out for the wiring.
CTE (ppm/C)
Steel 11-12
Aluminum 21-23
Copper 16-17
Brass 18-19
So, with either a copper or aluminum wire under a brass screw, the CTEs
aren't too far different, but going to an aluminum wire under a steel
screw, you've got a much larger range. and if the steel screw isn't
super tight, when things shrink, the aluminum shrinks more than the
steel and the contact gets loose.
You *can* do steel to clamp aluminum and/or copper - You just need to
have enough force that in the cold state, there's still contact (you're
relying on the stretchyness in the bolt and the squishyness of the
copper or aluminum. A large high strength stiff bolt is exactly the
wrong thing here.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|