[TowerTalk] Scotchkote and Liquid Tape

Kurt Andress ni6w@yagistress.minden.nv.us
Wed, 04 Nov 1998 08:36:41 -0800

John R Bookout K7JB wrote:

> Kurt:
> Your description of scotchkote made me think of perhaps another use.  In
> the 1970's, use of aluminum as electrical conductors in wiring homes and
> buildings was practiced in the area where I live.  Personally, I do not
> know what the county inspectors were thinking when they allowed and
> condoned this practice, because over time, aluminum oxidizes readily and
> looses its ability to remain a good conductor, especially when cut and
> joints are made.  As a result, when  aluminum conductors are joined by a
> wire nut or some other mechanical connection, the joint soon develops an
> electrical resistance, hence when current flows through the joint we see
> IR drop and heat.  This leads to electrical fires in these buildings
> constructed with aluminum wire.
> A contractor friend of mine and I got into this conversation the other
> day and he believes that the integrity of an electrical connection can
> be maintained over time if oxygen and water is kept away from the
> joint.  As I understand it, it is even possible to join aluminum and
> copper in connectors labeled CU-ALR along with a special paste to keep
> the joint from oxidizing.  I have never seen nor used scotchkote, but
> from your description I began to wonder if it would be yet another
> product to use in making these kinds of connections.  Any comments?
> Thanks John

Hi John,
I think it would be hard to apply the coating to house wiring conections and effect a
really good seal.
One definitely should use the conductive paste recommended for these connections.
The problem is that after assembling the connection with paste, we would need to clean
the paste from adjacent areas and then apply the Scotchkote to completely surround the
With circuit breaker connections we could seal the outer exposed half but not the inner
side. The same goes for those stupid wall plugs that have a small hole that the
installer just pushes the wire into. I like the old fashioned ones that have a screw
and bent wire eye. They have a lot more contact area and could be sealed.

I think a clever guy could make use of the coating to help the situation, but probably
couldn't get 100% sealing of all connections.

73, Kurt

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