Circuit Breaker Guide

Circuit Breaker Guide

Circuit breakers are essential safety devices for every building, warehouse and all edifices that use electricity. They act as the third party or arbitrators within complicated and otherwise dangerous electrical wiring systems. When met with excessive current, wiring systems can cause fires, power surges and explosions. But before such dangerous reactions can occur, circuit breakers step in by cutting the electrical power.


These box-like contraptions work by limiting the current in a single circuit. Without circuit breakers, your facility would be under constant danger and disorder. There are three main types of circuit breakers: standard, AFCI circuit breakers and GFCI breakers.

Here’s what you need to know about them:

Types of Circuit Breakers

Standard Circuit Breakers

Standard circuit breakers come in two varieties: single-pole breakers and double-pole breakers. These are simpler breakers that monitor the cadence of electricity as it circulates an indoor space. It keeps track of electricity in electrical wiring systems, appliances and outlets. This kind of breaker stops the current during overloads and short circuits to prevent wires from overheating. This can take place when a hot wire contacts a ground wire, another hot wire or a neutral one. This current shutoff prevents electrical fires.

Here’s a little bit more about both single-pole and double-pole breakers:

Single-Pole Breakers

  • The more common breaker
  • Protects one energized wire
  • Supplies 120V to a circuit
  • Handles 15-20 amps

Double-Pole Breakers

  • Has two single-pole breakers with a handle and a shared trip mechanism
  • Protects two wires
  • Supplies 120V/240V or 240V to a circuit
  • Comes in 15-200 amps
  • Used for large appliances like water heaters

GFCI Circuit Breakers

GFCI circuit breakers, or ground fault circuit interrupter circuit breakers, stop electrical power to circuits when they have overloading currents. They also come into effect on a short circuit or a line-to-ground fault. The latter happens in unwanted path formations between an electrical current and a grounded element. These breakers are not suitable for appliances that run continuously like refrigeration or medical devices. The reason lies in tripping; the breakers may trip more than it should.

Here’s some more information on GFCI breakers:

  • Defined by coiled wires and test buttons on their front sides
  • Essential for use in damp locations like basements, outdoor spaces, bathrooms, kitchens and garages
  • Handy in workstations that utilize power tools
  • Have a standard I” per pole plug-in

AFCI Circuit Breakers

AFCI circuit breakers, or arc fault circuit interrupters, stop an inadvertent electrical discharge in an electrical cord or wiring system that can result in a fire. It does so by sensing an abnormal path and an electrical jump, after which it disconnects the damaged circuit from the power before the arc catches a supply of heat hot enough to catch flame.

Here’s some more about AFCI circuit breakers:

  • Arcs are the products of aging or damaged electrical cords and wires
  • Needed alongside regular or standard breakers because they respond to a steadily built-up heat supply instead of quick surges
  • Responsible for protecting the branch circuit wiring in an electrical system

Best Circuit Breakers by Case

Breaker Type Best Use
Standard Circuit Breakers Protection of property, equipment and appliances due to electrical fault
GFCI Circuit Breakers Protection from electrical shock in areas where shock may occur like wet areas, laundry rooms, garages, kitchens, or outdoors
AFCI Circuit Breakers In place of standard circuit breakers to reduce the potential of arcing being an ignition source resulting in a fire

How to Replace a Circuit Breaker

  • Wear safety gear like lineman’s gloves, rubber shoes and safety goggles and stand on a safety mat. Make sure there is no liquid around.
  • Find the main circuit breaker box and the defective breaker.
  • Test for power with a voltage tester.
  • Shut off the branch breaker boxes, then the main power and finally the individual breakers.
  • Inspect the exterior of the panel for discoloration or rust.
  • Take out the screws on the face plates with a screwdriver.
  • Determine the type of breaker box you’re using by reading the label on the main power switch.
  • Check the panel’s interior for rust, melting, discoloration, heat marks, lost wires, pest intrusions, strange forms, debris, many wires under one screw, wiring with damaged insulation or multiple colored wires.
  • Make the screw loosen up on the defective breaker wires.
  • Remove the breaker.
  • Discard the old circuit breaker.
  • Place a new one in the same spot as the old one.
  • Add the wires in the new breaker and screw them in tightly.
  • Replace the panel’s faceplate.

More on Circuit Breakers

AFCI and GFCI circuit breakers work against arc and ground faults, respectively. Although they work on separate facets of an electrical wiring system, the two of them in tandem provide the utmost circuit protection.

AFCI and GFCI complement each other especially in places with complicated circuitry, while the standard circuit breakers can work among simpler circuits. Neither of these circuits require any specialized wiring or installation guidelines.


Pub. 3/2017

The product statements contained herein are intended for informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness for a specific application or use. W. W. Grainger, Inc. does not guarantee the result of product operation or assume any liability for personal injury or property damage resulting from the use of such products.