Re: galvanic reaction

["Mel" <Respond@xxxxxxxxxxxxx>]

"Dr. Phil" <nospam@xxxxxxxxxx> wrote in message
news:F_U2e.7477$vK6.770@xxxxxxxxxxxxxxxxxxxxxxxxx
> 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.

Low wattage resistor leads are typically tinned copper, not aluminum. The
leads connect internally to the resistive part which is usually carbon film.
In the old days, it was carbon composition.

Bob