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

Description:

The Zinsco Q243040 (Type Q-24) is a 3-pole 40 Amp molded case circuit breaker designed for use in legacy Zinsco / GTE Sylvania load centers and panelboards. It operates on 240 VAC systems and uses a thermal-magnetic (Magnatrip) trip mechanism to protect circuits from overloads and short circuits. This breaker is typically a plug-in style (Q series) or available in bolt-on variants (QB series) depending on panel configuration.

Applications:

The Q243040 breaker is commonly used in industrial and commercial three-phase electrical systems, including motor control panels, machinery circuits, and distribution boards requiring 40A protection. It functions as a branch or feeder breaker for equipment such as pumps, compressors, and light industrial loads. These breakers are now obsolete and typically available only as surplus or reconditioned units.

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 (Q series) / Bolt-on (QB series)
• Phase: 3-phase
• Status: Discontinued / obsolete

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