As shown in figure "A" of the illustration,...

🔍 Key Concepts

• Look closely at figure A and trace how the fuses connect to the ground bus and disconnect switch. • Think about what condition is safest for a technician working on the fuses during maintenance – should the fuses be connected to ground or isolated from ground? • Notice the mechanical interlock between the door, the disconnect, and the ground connection, and what it does when the switch is opened or closed.

💭 Think About

• When the disconnect handle is moved to the OPEN position, what happens to the path from the fuses to the ground bus in the drawing? • In the CLOSED position, do the fuses appear to have a solid path to ground, or are they only connected to the line side (L1, L2, L3)? • Which switch position (open or closed) would you expect to be used when someone is physically handling or replacing the fuses?

✅ Before You Answer

• Verify which conductor symbol actually goes to the ground bus and how it changes with the position of the disconnect. • Confirm whether the ground connection is engaged in the OPEN or CLOSED position of the disconnect by following the dashed/mechanical interlock lines. • Ask yourself: for maintenance safety, would the design intentionally leave energized parts floating, or would it provide a direct ground path to discharge stored energy and prevent shock?

As shown in figure "A" of the illustration, what statement is true concerning the safety disconnect switch? See illustration EL-0172.

When the disconnect switch is opened, the fuses are automatically disconnected from ground for maintenance safety.

When the disconnect switch is opened, the fuses are automatically grounded for maintenance safety.

When the disconnect switch is closed, the fuses are automatically grounded for maintenance safety.

When the disconnect switch is closed, the fuses are automatically disconnected from ground for maintenance safety.

🔍 Key Concepts

💭 Think About

✅ Before You Answer