This afci is designed for use only in the wire guide series of Siemens load centers. For use in standard es, pl, eq, or ultimate Siemens series load centers, use the catalog numbers without the "wg" at the end. The combination type afci differs from the branch/feeder afci in its ability to detect series arcing faults. The branch/feeder afci can only detect line-to-neutral and line-to-ground arcing faults. Combination afcis provide protection against the high-energy parallel (line-to-neutral and line-to-ground) arcing and low-energy series arcing. "Combination" does not mean an afci + GFCI. Combination = parallel + series arcing. Combination afcis protect downstream branch circuit Wiring, cord sets, and power supply cords. Siemens combination type afci trip indicators provide a valuable analysis tool to help electricians pinpoint the type of trip. These indicators are in the form of leds that appear near the handle of the breaker. The LED indications will appear for 5 seconds each time the afci is turned "on" up to 30 days after the last trip.