Chapter 15: Overcurrent Protective Devices

Basic OCPD Concepts

100

This device shuts off power when too much current flows.
 

OCPD - Overcurrent Protection Device

200

This occurs when equipment operates beyond its rated ampacity.

Overload

300

This type of fault happens when a hot wire contacts a neutral or ground.

Short circuit

400

This type of fault occurs when a hot conductor touches a grounded surface like a metal box.

Ground fault

500

This dangerous condition involves current flowing through an unintended path, creating high heat and sparks.

Arc fault

Types of Faults

100

This happens when too many devices are plugged into one circuit.
 

Overload

200

This type of arc fault occurs when a conductor is broken and current jumps a gap.Series arc fault
 

Series arc fault
 

300

This type of arc fault can occur when a nail punctures a cable.

Parallel arc fault

400

This type of fault creates extremely high current due to very low resistance.

Short circuit

500

Explain the key difference between a ground fault and a short circuit.
 

Ground fault = current to ground; Short circuit = hot to neutral/another conductor

Fuses

100

This happens inside a fuse when excessive current flows.
 

The link melts, opening the circuit

200

These are the two general types of fuses.

Plug and cartridge

300

This is the maximum amp rating for plug fuses.

30 amps

400

These fuses prevent incorrect replacement by using adapters.
 

Type S fuses

500

Why are Edison-base fuses considered dangerous?
 

They allow higher-rated fuses to be installed, creating a fire hazard

Circuit Breakers

100

Unlike fuses, circuit breakers can do this after they trip.

Be reset

200

This type of breaker supplies 120 volts.

Single-pole breaker

300

This type of breaker connects to both legs of a panel.
 

Double-pole breaker

400

This breaker type allows two circuits in the space of one.
 

Tandem breaker

500

Why must panels be designed specifically for tandem breakers?
 

To prevent overloading and ensure safe operation of the panel

AFCI and GFCI Protection

100

This device protects people from shock by detecting current imbalance.

GFCI

200

This device helps prevent fires caused by arc faults.
 

AFCI

300

A GFCI trips at approximately this current level.

6 mA

400

Name two locations where GFCI protection is required.

Bathrooms, kitchens, outdoors, garages, basements, etc. (any two)

500

Name the 3 places that AFCI Protection is NOT Required in a residence.

Bathrooms, Garages, Outside Receptacles