You could always do something exciting like this tidbit I wrote last night.
26 05 19 CONDUCTORS
1. Section Includes: wires, cables, and connectors for power, lighting, signal, control and related systems rated 600 volts or less.
2. Materials:
a. Conductors shall be copper, 98.5% conductivity except where specifically noted otherwise on Drawings.
b. All wire and cable for feeders and branch circuits shall have copper conductors and shall be 600 volts, 90 degree C., NEC type conductors with THHN/THWN-2 insulation. Conductors for services shall have XHHW-2 insulation.
c. The contractor may provide alternate pricing for the use of aluminum alloy conductors for copper feeders sizes #1 AWG and larger indicated on the plans.
d. Where allowed by the authority having jurisdiction, the use of metal clad cable is permitted.
You only use XHHW-2 insulation???
I never go less than XJJY-4 insulation...