According to the CEC, when a transformer is supplied from a feeder or branch circuit, and the transformer has a primary overcurrent device set at not more than 2.5 times the primary rated current (for circuit breakers) and the secondary conductors are protected by an overcurrent device, what is the maximum length of secondary conductor permissible without additional protection at the transformer secondary terminals?

Question: According to the CEC, when a transformer is supplied from a feeder or branch circuit, and the transformer has a primary overcurrent device set at not more than 2.5 times the primary rated current (for circuit breakers) and the secondary conductors are protected by an overcurrent device, what is the maximum length of secondary conductor permissible without additional protection at the transformer secondary terminals?

Answer options:

• 1.5 m (5 ft)
• 3 m (10 ft) ✅ 7.5 m (25 ft)
• Not permitted; secondary conductors always require protection at the transformer terminals.

Correct answer: 7.5 m (25 ft)

Explanation: CEC Rule 26-258(3)(c) allows for secondary conductors up to 7.5 m (25 ft) in length without individual overcurrent protection at the transformer secondary terminals, provided the primary overcurrent device is rated no more than 2.5 times the primary rated current (for circuit breakers) and certain other conditions are met, including the secondary conductors terminating in a single overcurrent device or set of devices rated for the conductor's ampacity.