Re: galvanic reaction

[not_real@xxxxxxx (Beachcomber)]

On Thu, 31 Mar 2005 10:53:31 -0500, "Dr. Phil" <nospam@xxxxxxxxxx>
wrote:

>Why do manufacturers give us resistors that are made of a different
>metal than the copper wire we are using?  High voltage electricians know
>that you can't connect an aluminum and copper wire directly to each
>other.  Roofers know you can't nail copper flashing with aluminum nails.
>Simple moisture in the air can cause galvanic reaction between the
>copper wire and whatever the resistors are made out of [looks like
>aluminum] causing the least noble metal to deteriorate.  Yes Robert it
>does happen, even if you haven't noticed it in your 40 years in the
>trade.;)  Any resistor experts out there?  Why are most resistors I have
>seen not made out of copper?  Must be some reason.

Well for one thing, the same reason why the overhead wires that are
strung down the road are not made of copper.  Copper corrodes when
exposed to air.   The other reason is that copper is a conductor - if
you want something like 10 ohms or so, that is going to be a pretty
thin wire.

Beachcomber