>Aluminum house wiring got a bad rap from builders who used it exactly
>like they used copper. I have no doubt that properly engineered,
>aluminum house wiring can be just as safe as copper and possibly a lot
>cheaper as well. It will require some new technology, but nothing
>approaching rocket science. Time will tell.
One of the problems is that aluminium remains in a semi-molten state, even
at cold temperatures. With steady mechanical pressure applied, it "flows"
away from the pressure points, so it is impossible to maintain permanent
connection with a clamp. The metal in the wire flows away from the clamp,
causing it to loosen up. That is the primary cause of to-day's line noise
problems. The high voltage wire, at approximately 11kv in medium voltage
distribution systems, is now almost always aluminium. It used to be copper.
Our local power company actually ripped down all the old copper wire and
replaced it with aluminium years ago during a previous copper price spike,
in order to sell the copper as scrap for a substantial profit.
The clamp that attaches the pigtail lead running from the pole transformer
to the HV wire eventually works loose under pressure, causing the connection
to the HV wire to arc. Lineman have a specific term for this in their
jargon: a "hot clamp."
I once had a severe problem and was able to easily locate it. I called the
emergency number at night to report it because I could talk directly with
the line repairman, instead of having my message get lost through numerous
secretaries at the power company's main office during the day. I told him
that it wasn't a real emergency, and that it would be ok with me if they
just waited till the next day to send the regular repair crew out to fix it.
He told me that no, it WAS an emergency, and that they would be out that
night to make the repair. An arcing clamp can actually cause the HV wire to
burn in two, resulting in a 11kv line on the ground where someone could
inadvertently come in contact with it. Within a couple of hours the noise
was gone.
You would think that by now, some new technology to connect the transformer
to the HV line would have been developed, since this is such a pervasive
problem. It costs the power company money not only in the replacement
material and manpower required to constantly tend to malfunctioning clamps;
a considerable amount of electric power is lost, or wasted, whenever these
arcs occur. They are sometimes called "power leaks," analogous to leaks in
a gas or water line. As you said, this isn't exactly rocket science.
Don k4kyv
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