Copper's greater conductivity versus other metals enhances the electrical energy efficiency of motors. This is important because motors and motor-driven systems account for 43%-46% of all global electricity consumption and 69% of all electricity used by industry. Increasing the mass and cross section of copper in a coil increases the electrical energy efficiency of the motor. Copper motor rotors, a new technology designed for motor applications where energy savings are prime design objectives, are enabling general-purpose induction motors to meet and exceed National Electrical Manufacturers Association (NEMA) premium efficiency standards.

What property of copper increases the efficiency of electrical motors?