If power is supplied to a building by underground cables, the shutoff may be located in which place?

• A. The basement of the building
• B. An underground vault
• C. The exterior meter box
• D. The roof

Answer: (B)

When power comes to a building through underground cables, the shutoff is placed in an exterior underground vault near the structure. This setup allows firefighters to rapidly disconnect power from outside, without entering the building, and the vault keeps the main disconnect and service conductors dry and protected. A basement shutoff would require entering a burning or unstable building, which is unsafe; an exterior meter box may only house metering equipment and might not provide the required disconnect; a rooftop location is not practical or safe for electrical service. So, the underground vault is the appropriate placement for the shutoff in this scenario.