When should I apply the 125% continuous load factor?

According to section 8-104 of the Quebec Construction Code, a continuous load is a load that operates for 3 hours or more without interruption. For these loads, the conductor and protection device capacity must be at least 125% of the load's rated current.

Example: A 4,500 W water heater at 240 V normally draws 18.75 A. Since it operates continuously, calculate: 18.75 × 1.25 = 23.44 A. You must use a #10 AWG conductor (30 A) and a 25 A breaker (or 30 A if 25 A is not available).

This factor applies to: water heaters, heat pumps, air conditioners, commercial lighting (> 3 h), and electric vehicle chargers. Forgetting to apply it is a common mistake on the CMEQ exam.