What device protects circuits from overload?

• A. Voltage is electrical pressure pushing current
• B. AC Current
• C. Three-Phase Power
• D. Fuse protects circuits from overload

Answer: (D)

Overcurrent protection is provided by devices that interrupt current when it becomes unsafe. A fuse does this by containing a metal conductor that melts when the current exceeds its rating; the melting breaks the circuit, stopping the flow and preventing wires from overheating. Fuses are rated in amperes, so a higher overload or a short circuit causes faster melting. They are placed in series with the circuit, and once a fuse blows, it must be replaced to restore protection. The other options describe electrical quantities or delivery methods, not protective devices: voltage is the pressure pushing current, while AC current and three-phase power describe how electricity is supplied, not how overloads are prevented.