Zinsco Type Q-24 Q243040 3 Pole 40 Amp 240V Circuit Breaker AK

Description:

The Zinsco Q243040 (Type Q-24, “AK” variant) is a 3-pole 40 Amp molded case circuit breaker designed for legacy Zinsco / GTE Sylvania panelboards. It operates at 240V and uses a thermal-magnetic trip mechanism to protect three-phase circuits from overloads and short circuits. This breaker is typically a plug-in or bolt-on style (depending on panel type) and was part of the Zinsco Q-series, now discontinued. 

Applications:

The Zinsco Q243040 breaker is widely used in industrial and commercial three-phase electrical systems, including motor control panels, distribution boards, and machinery circuits requiring 40A protection. It serves as a branch or feeder breaker for equipment such as pumps, compressors, and light industrial loads. Due to its legacy design, it is now obsolete and typically sourced as refurbished or surplus, with modern replacements often recommended.

Technical Specifications:

• Manufacturer: Zinsco / GTE Sylvania / Challenger
• Model / Part Number: Q243040 / Q24-3040
• Product Type: Molded Case Circuit Breaker
• Poles: 3-Pole
• Current Rating: 40 Amps
• Voltage Rating: 240 VAC
• Interrupt Rating: ~10 kAIC @ 240V
• Trip Type: Thermal-magnetic (LI – long-time & instantaneous)
• Mounting: Plug-in / Bolt-on (panel dependent)
• Phase: 3-phase
• Status: Obsolete / discontinued (surplus or reconditioned only)

Common Replacements:

• Square D QOB340 3-Pole 40A Bolt-On Circuit Breaker
• Siemens BQD340 3-Pole 40A Bolt-On Breaker
• Eaton BAB3040H 3-Pole 40A Bolt-On Breaker