When sourcing motor wire, the most critical factor is the Conductor Material, typically 99.9% Oxygen-Free Copper for high conductivity or Copper-Clad Aluminum (CCA) for cost-sensitive applications. You must specify the Thermal Class (e.g., Class H 180°C, Class C 200°C, or 220°C) to ensure the insulation can withstand the motor's operating heat. Additionally, verify the Insulation Type, such as Polyesterimide (PEI) or Polyamide-imide (PAI), and the Insulation Thickness (Grade 1, 2, or 3), as this determines the dielectric strength and breakdown voltage.