The ESA, and Ontario Electrical Safety Code (OESC) set firm standards for handling aluminum wiring in residential properties. While the code allows aluminum conductors in some applications, it prohibits their use in branch circuit wiring under 40 amps. Specifically, aluminum wiring smaller than #6 AWG is not permitted for residential branch circuits. https://www.canadianwirewizards.ca/understanding-the-ontario-electrical-safety-code-on-aluminum-wiring/