4 ms·

If talking about motors, they used to use copper for the windings. Now they use aluminum wire, which works perfectly fine, until there is a power surge in wh

If talking about motors, they used to use copper for the windings. Now they use aluminum wire, which works perfectly fine, until there is a power surge in which case the aluminum overheats and the motor is now dead.

oasisbob 10y ago
Got a source for that? As I understand it, aluminum wound transformers are more reliable than copper under surge conditions because aluminum has a much higher specific heat than copper - providing more of a thermal buffer prior to damage. Motors aren't transformers, but I'm having a hard time seeing how this same effect wouldn't be in play.
- patrickg_zill 10y ago
  My source for the explanation of motors in household appliances wearing out, is from people who are in the commodity metals recycling industry (i.e. metals like steel/copper/alu sold for scrap and recycled). So it is based on what they are seeing - there might be some bias, as obviously they are only seeing those units that have been sent off for scrap. Aluminum wiring in houses, has some known problems, such as metal fatigue and differences in thermal expansion between copper and aluminum: http://www.alwirerepair.com/aluminum-wiring-whats-the-problem http://www.alwirerepair.com/aluminum-wiring-whats-the-proble... What might be the case, is that as copper increased in price, manufacturers quickly switched to aluminum but did not allow/adjust properly either for the greater expansion of aluminum when heated, or, did not have their anti-oxidation finishes that coat both the wire and the terminals, perfectly adjusted. If so, current "second generation" motors should be failing at a much lower frequency - but we might not see that as an effect yet due to that group being newer overall. Aluminum conducts electricity much better than aluminum oxide, which forms almost immediately if aluminum is scratched or otherwise exposed to air, thus the anti-oxidation finish.

oasisbob 10y ago

Got a source for that? As I understand it, aluminum wound transformers are more reliable than copper under surge conditions because aluminum has a much higher specific heat than copper - providing more of a thermal buffer prior to damage. Motors aren't transformers, but I'm having a hard time seeing how this same effect wouldn't be in play.

patrickg_zill 10y ago
My source for the explanation of motors in household appliances wearing out, is from people who are in the commodity metals recycling industry (i.e. metals like steel/copper/alu sold for scrap and recycled). So it is based on what they are seeing - there might be some bias, as obviously they are only seeing those units that have been sent off for scrap. Aluminum wiring in houses, has some known problems, such as metal fatigue and differences in thermal expansion between copper and aluminum: http://www.alwirerepair.com/aluminum-wiring-whats-the-problem http://www.alwirerepair.com/aluminum-wiring-whats-the-proble... What might be the case, is that as copper increased in price, manufacturers quickly switched to aluminum but did not allow/adjust properly either for the greater expansion of aluminum when heated, or, did not have their anti-oxidation finishes that coat both the wire and the terminals, perfectly adjusted. If so, current "second generation" motors should be failing at a much lower frequency - but we might not see that as an effect yet due to that group being newer overall. Aluminum conducts electricity much better than aluminum oxide, which forms almost immediately if aluminum is scratched or otherwise exposed to air, thus the anti-oxidation finish.