A UL publica um guia sobre marcações de fios e cabos:
Guia de marcação e aplicação UL
https://www.ul.com/wp-content/uploads/2014/04/WC_MG.pdf
Conductor Material
Compact stranded copper conductors are identified by “compact” or “cmpct,” otherwise wire and
cable with bare or coated copper conductor material is not marked with stranding identification.
If the conductor material is either aluminum or copper-clad aluminum, the product, tag or carton
markings (depending on the product category) identify the conductor material. These markings
will appear as “AL,” “ALUMINUM,” “AL (CUCLAD),” “ALUMINUM (COPPER-CLAD),” “CU-CLAD
AL” or “COPPER-CLAD ALUMINUM.”
For some wire and cable, other metals may be used as conductor material. The associated
markings for that wire and cable are explained under the heading “OTHER.”
O "padrão" é de fato cobre.
No entanto, o AWM na marcação me levaria a acreditar que isso pode ser algo diferente de construir fios por NEC:
This guide does not address wire and cable evaluated only for suitability as factory-installed
component wiring in other Listed equipment. Those products are Recognized by UL under the
Component-Appliance Wiring Material (AWM) and Component-Nonshielded cable categories and
are not identified with an NEC® wire Type designation.