Square D NSB FA24040AB Molded Case Circuit Breaker

The Square D FA24040AB is a two-pole, 40 A molded‑case circuit breaker from the FA frame family, rated for 480/277 V and configured for 2P/1PH service with I‑Line plug‑in mounting for quick replacement in compatible Square D panels. It uses a thermal‑magnetic trip mechanism to provide overload and short‑circuit protection, and carries an 18 kA interrupting rating at 480 V to handle fault currents typical in commercial and light industrial distribution. The unit is rated for a 40 °C ambient environment and is designed for protecting feeders and branch circuits in 480Y/277 V systems, such as lighting, motor loads, and general equipment circuits within FA‑series panelboards and enclosures. As a legacy FA MCCB, it integrates with other FA components and Square D labeling, offering dependable overcurrent protection in mid‑range applications where reliable protection and straightforward replacement are required.