If the breaker is made by Square D, which is the most popular brand of panels and breakers in the U.S., then the yellow test button indicates that it is a GFCI (Ground Fault Circuit Interrupter) breaker and a white button means the breaker is an CAFCI ( Combination Arc Fault Circuit Interrupter). Square D breakers that are more than about 20 years old with a red ‘TEST’ button are GFCI, and AFCI breakers (an earlier version of CAFCI) had green test buttons. Other brands, like Siemens and Cutler Hammer, use their own color code, most often red or white.

     There is very tiny print of the front surface of the breaker, but concealed under the metal dead front, that states which type of breaker it is; but we do not recommend removing the dead front to check. The photo above shows a CAFCI breaker with the dead front removed and a label indicating that it is a Combination AFCI.

     The GFCI breakers are used to provide additional shock protection in wet areas of the home, and CAFCI and AFCI breakers recognize arcing/sparking in the wiring and trip to avoid starting a fire. Both types also provide the same overcurrent protection as other breakers in the panel.

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Here’s links to a collection of our other blog posts about AFCI and GFCI RECEPTACLES AND CIRCUIT BREAKERS:

• Does a septic pump or sump pump require a GFCI-receptacle?

• What is the difference between what trips a GFCI (ground fault) receptacle and a circuit breaker?

• Are Ground Fault Circuit Interrupters (GFCIs) really necessary and worth the trouble? 

• What is the code requirement for GFCI protection for receptacles near a wet bar sink?

• When was GFCI-protection for kitchen dishwasher receptacle outlet first required? 

• When did arc fault circuit interrupter (AFCI) breakers first become required?

• Does a washing machine receptacle outlet require GFCI protection?

• My spa tub stopped working. What's wrong?  

• How do I identify a combination AFCI (CAFCI) circuit breaker? 

• What does "listed and labeled" mean for an electrical component? 

• What electrical hazards does a Ground Fault Circuit Interrupter (GFCI) NOT protect against?  

• What is the difference between GFCI and AFCI circuit breakers? 

• Where are GFCI receptacle outlets required?

• What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?  

• What is the difference between "grounded" and "grounding" electrical conductors? 

• What does it mean when a wire is "overstripped" at a circuit breaker?

• Why is there a GFCI breaker in the electric panel for the bathroom shower light and exhaust fan?

• What is the switch on the wall with two pushbuttons? 

• How far apart should kitchen counter receptacles be spaced?  

• How far above a kitchen countertop do electrical outlets have to be? 

• How is it possible to provide both GFCI (Ground Fault Circuit Interrupter) and CAFCI (Combination Arc Fault Circuit Interrupter) protection for kitchen and laundry circuits?

• My bathroom electric receptacle/outlet is dead and there are no tripped breakers in the electric panel. What's wrong?  

• My GFCI reset button is hard to push and won't reset. What's wrong?

• Why do some breakers in my electric panel have a "TEST" button on them?

    Visit our AFCI AND GFCI page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.