What is the difference between a CAFI and an AFI circuit breaker?

How is a Combination Arc-Fault Circuit Breaker (CAFI or CAFIC) different than an Arc-Fault Circuit Breaker (AFI or AFIC)? Some of the breakers have a suffix CAFI, and are called Combination Arc-Fault Breakers. But there are also breakers that have a suffix AFI, and are called Arc-Fault Breakers. What is the difference?

Resolution:First, be aware that whether it is an AFI or CAFI breaker, both types also include the thermal/magnetic protection for overloads and short circuits that a standard circuit breaker has. As to the difference in AFI and CAFI, here are the details:AFI or AFIC Suffix
Circuit breakers with suffix AFI or AFIC primarily detect parallel arcing (branch/feeder).The push-to-test button is green or blue.

These will trip under these conditions:(1) The breaker detects a downstream overload or short circuit (per trip curve)
(2) The breaker detects a downstream arc to ground in the range of 30-50ma or greater, regardless of the load.(3) The breaker detects a downstream arc that meets certain preset conditions, plus at the same time the breaker is carrying 50A or more of load current, even if very briefly. This 50A maximum value used in breakers is lower than UL1699 value of 75A for arc-fault circuit breakers.

CONCLUSION: AFI Arc-Fault Circuit Breakers are designed to provide protection against overloads, short circuits, and parallel arcs (H-N), and will trip on arcs to ground in the range of 30-50ma or higher. CAFI or CAFI Suffix
Circuit breakers with suffix CAFI or CAFIC detect parallel arcing plus series arcing (branch/feeder/outlet).The push-to-test button is white.

These will trip under these conditions:(1) The breaker detects a downstream overload or short circuit (per trip curve)
(2) The breaker detects a downstream arc to ground in the range of 30-50ma or greater, regardless of the load.(3) The breaker detects a downstream arc that meets certain preset conditions, plus at the same time the breaker is carrying 5A or more of load current, even if very briefly. The 5A value is per UL1699 for combination-type arc-fault circuit breakers.

CONCLUSION: CAFI Combination Arc-Fault Circuit Breakers are designed to provide protection against overloads, short circuits, parallel arcs (H-N), and series arcs (H-H same phase), and will trip on arcs to ground in the range of 30-50 ma or higher.