Installing Circuit
Protection Devices

[lesson title]

IDENTIFYING CIRCUIT PROTECTIVE DEVICES

Circuit protective devices are installed in the circuit to protect it and other equipment in the circuit from an overcurrent or overload. The words overcurrent and overload are used interchangeably, but thy have different meanings.

• Overcurrent describes a condition in which a circuit is carrying more than its rated load of amperes.
• Overload describes the starting load of motors and motor-driven appliances. Motors require heavy current flow when starting and much less current at normal running speed.

In order to prevent overcurrent and overload, electrical circuits have been designed with built-in protective devices. Typical circuit protective devices are fuses, circuit breakers, and ground-fault circuit interrupters (GFCIs) (Figure 1-1).

Figure 1-1.   Types of circuit protective devices

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