An electrician is inspecting an existing 120/208 V, 3-phase, 4-wire, 100 A service entrance in a community centre. The main service disconnect is located on the exterior wall. What is the maximum length allowed for the service conductors between the point of entry into the building and the main service disconnect switch, assuming the conductors are enclosed in rigid metal conduit?

Question: An electrician is inspecting an existing 120/208 V, 3-phase, 4-wire, 100 A service entrance in a community centre. The main service disconnect is located on the exterior wall. What is the maximum length allowed for the service conductors between the point of entry into the building and the main service disconnect switch, assuming the conductors are enclosed in rigid metal conduit?

Answer options:

• No maximum length specified, provided fire spread is accounted for.
• 1.5 m (5 ft)
• 3 m (10 ft) ✅ As short as practicable, not exceeding 7.5 m (25 ft).

Correct answer: As short as practicable, not exceeding 7.5 m (25 ft).

Explanation: CEC Rule 6-200(1) requires the service box (main service disconnect) to be located as close as practicable to the point where the service conductors enter the building, or where they leave an embedded or enclosed raceway, and in no case shall the service conductors within the building exceed 7.5 m (25 ft) to the service box.