Can someone explain this?
 

On Fri, 20 Feb 2004 04:23:20 GMT, "RichG"
wrote:

Hell, I owned a house that was wired with aluminum. With the right outlets
and switches, it was perfectly fine. With the wrong ones. it was a fire
waiting to happen. The subdivision that I lived in is a few blocks away from
this one and I haven't heard of an electrical fire since it was built in
'75. My buddy is a fireman and he hadn't heard of one either. Lots of
press. Some bad problems, but not as bad as most would make it out to
be...RichG

That's not true either. The problems were a lot less when they started
using the proper connectors. But they still persisted and so most
municipalities now don't allow aluminum house wiring. Some do, most
don't.

Steve

Can someone explain this?
 

.
Aluminum has far better conductivity per pound than does copper.

True, but it's much bulkier. An aluminum wire has to be much bigger than a
copper wire, if both are rated to carry the same wattage

... It is
also stronger per pound. And it is cheaper.

Not in marine grades, it isn't.



Steven Shelikoff wrote:
.... in applications where weight is critical, such as spacecraft,
aircraft, etc., they use copper instead of aluminum.

In a lot of aviation applications, and for sensitive instruments, platinum &
gold are used. Clearly not where cost is an issue though ;)

DSK

Can someone explain this?
 

"Steven Shelikoff" wrote in message
...
On Thu, 19 Feb 2004 21:47:41 -0600, "del cecchi"
wrote:

It is still widely used, now that the proper connectors have been
developed. The newly installed line from the transformer on the pole to
my house for my upgraded service is Aluminum, as was the old one.
Aluminum has far better conductivity per pound than does copper. It is
also stronger per pound. And it is cheaper.

That's only because it's so light, not because it's such a great
conductor. In applications where it has to be suspended, like high
voltage lines or the feeder line to your house, it's fine. But if you
don't have to suspend it, like boat, house or car wiring, you're better
off with the higher conductivity of copper.

Copper is 2.7/1.7 or 1.58 times a better conductor. So a wire would have to
have a diameter 1.26 times as great in aluminum. However the density is
8.96/2.7 or 3.3 times as high for copper so a copper wire with the same
resistance weighs twice as much.

Aluminum is .78/1.3 or .6 times as expensive, so to net it out, a copper
wire costs about 3.5 times as much for the material as does an aluminum wire
for the same resistance.

Even in applications where weight is critical, such as spacecraft,
aircraft, etc., they use copper instead of aluminum. For instance, the
international space station has many miles of electrical wire. Think of
all the weight savings and cost savings that could have been had by
using aluminum. The structural components are aluminum but the wiring
is copper despite Al's better conductivity per pound. There's a reason
for that... because it's not a great conductor.

Steve

I would guess that space in the wiring areas and mechanical properties are
most important in the space station. In boats, corrosion resistance. These
could both favor copper over Al.

del cecchi