A one-line diagram for a power distribution system is used to determine ___.

• A. All of these
• B. The path of electrical power
• C. Future expansion capacity
• D. Power shut-off points

Answer: (D)

One-line diagrams lay out the electrical distribution in a single, simplified path from source to loads, showing where protective devices and disconnects sit. This makes it easiest to see how power can be isolated, so you can identify exact locations to shut off power for maintenance or in an emergency. While you can trace the power flow on the diagram and it can help with planning future changes, those aspects aren’t the primary function of the diagram. The most direct and critical use is to determine where to shut off power quickly and safely.