What is the max temp I can expose aluminium wiring to before it starts to damage the wire? I'm looking to have wiring inside an atmosphere of 500-700 F. Would copper work also? I'm looking for a cheap for safe material to use. Thanks for your input!
aluminum begins to melt at approximately 660C (approx. 1,220F).so the resistance of the aluminium wire is melting point of the aluminium.
It depends on what aluminum wire you are using but conductor grade is essentially pure Al and the rule of thumb is that metals (pure metals) will be subject to creep at any temperature greater than one half the absolute melting point. MP of Al is 660C = 933K so half is 466.5K = 193.5C = 380F So... you will be well above the temperature where creep will be a concern. Creep is the time dependant deformation of metal under the influence of stresses less than the yeild stress. In your case, this might not be a problem if the wire will not be at that temperature for very long or is the wire will be under very very little stress. Think spagetti noodle. Copper would be better (although it will oxidize and the copper oxide will flake off). The creep temp for Cu is 761F. Cu is also a much better conductor (lower resistance in the same cross section), ~ 100% IACS vs 80% IACS for Al at room temperature. The electrical resistance of metals increases with temperature so these conductors are not going to be as good when hot. You need to consider if resistance may be an issue. If the electrical requirements are not that big a deal, the resistance wire used in toasters and blow dryers conducts electricity when hot (hotter than 700F). As far as safe material to use, you need to think about the consequences of failure. What does failure cost you in terms of time, materials, burning down your parent's garage, blowing up a preschool full of children run by nuns? Then decide how cheap is cheap.
The conductor is not as important as the insulation. The insulation has to be rated for the ambient temps. Call an electrician.
The melting point of aluminum is around 1200F and copper is around 2000F. That alone would make me rule out aluminum for your application.
