The NEC will provide tables for current carrying capacity of wires based on standard ratings. The wire will be rated according to type (solid or stranded, Al or Cu, etc.), diameter (in AWG or CM), by insulation type and insulation temp rating, and installation method (open air, conduit, etc). I am not familiar with aerospace applications, but I would bet that there are standards specific to that industry that would apply. The type of wire required for aerospace may or may not be included in the NEC tables.  

"Contacts" are subcomponents of a larger device such as a switch, relay, circuit breaker, contactor, etc. If you are interested in rating of any of the above devices, the manufacturer will provide specific ratings for such devices based on one or more standards (NEMA, IEC, IEEE, etc.). Please note that the current rating for a contactor (for example) will vary according to what standard it is rated by, so you will need to identify the standard which is required for aerospace.

I guess the short way to answer your question would be to identify the 'governing authority' for your application and follow the guidelines.  

Suggestions: Visit
1.
http://www.nfpa.org/
for current NFPA 70-1999 National Electrical Code (NEC), AWGs and related ampacities, temperatures, deratings, etc.
2.
http://208.156.24.64/standsearch/standards.asp
NEMA Standard and NEMA site
http://www.nema.org/standards/
http://208.156.24.64/standsearch/standards.asp
NEMA Std WC 51-1986
NEMA Std WC 50-1976
for more info.
When it comes to contact current carrying capacities/ampacities, it is better to be specific and contact manufacturers of specific equipment for specific applications.

Thank You!!!!!!



William H. Bernhart, P.E.
 
 
I work as a development engineer for AMP - Tyco Electronics located near Harrisburg, PA. I help design interconnections and electrical connectors for aerospace applications.