Square D's QO line is the original plug-on breaker for residential and light commercial load centers. This 2-pole 40-amp breaker provides 240V overload and short-circuit protection for high-draw appliance and HVAC circuits. Packaged on a hanging retail card.

• Amperage: 40 amps
• Poles: 2 (occupies two slots, 240V or 120/240V split-phase)
• Voltage rating: 120/240 VAC
• Interrupting rating: 10,000 AIR
• Thermal-magnetic trip mechanism for overload and short-circuit protection
• Visi-Trip indicator window shows a red flag when the breaker has tripped for fast troubleshooting
• HACR rated for heating, air conditioning, and refrigeration equipment
• UL Listed and ANSI certified
• Plug-on bus connection for QO load centers

Compatibility: Fits Square D QO load centers, QO enclosures, and NQOD panelboards. Does not fit Square D Homeline (HOM) panels, which use a different bus stab and require HOM-series breakers.

Common 2-pole 40A applications: Smaller electric ranges, larger electric water heaters, residential central AC condensers in the 3 to 4 ton range, and tankless point-of-use water heaters.

Installation Tip: De-energize the panel main and verify zero voltage with a meter before installing or replacing a breaker. Press the breaker firmly onto the bus stab until it snaps fully into place and confirm the toggle moves freely between ON, OFF, and the center trip position.