Zinsco QB24 QB QB243020 3 Pole 20 amp 240v Circuit Breaker

Description:

The Zinsco QB243020 (QB24 series) is a 3-pole 20 Amp molded case circuit breaker designed for use in Zinsco / GTE Sylvania panelboards. It operates on 240 VAC three-phase systems and features a thermal-magnetic trip mechanism that protects against overloads and short circuits. Unlike the Q-series plug-in models, this breaker is a bolt-on type, providing a more secure mechanical and electrical connection to the bus bar in commercial and industrial panels.

Applications:

The QB243020 breaker is commonly used in industrial and commercial electrical distribution systems, including panelboards, motor control centers, and machinery circuits requiring 20A three-phase protection. It is suitable for protecting small motors, control panels, and balanced loads. As part of the Zinsco QB bolt-on series, it is typically found in older installations and is now obsolete, usually available only as surplus or reconditioned units.

Technical Specifications:

• Manufacturer: Zinsco / GTE Sylvania / Challenger
• Model / Part Number: QB243020 / QB24-3020
• Product Type: Molded Case Circuit Breaker (Bolt-On)
• Poles: 3-Pole
• Current Rating: 20 Amps
• Voltage Rating: 240 VAC
• Phase: 3-phase
• Mounting: Bolt-on (QB series)
• Trip Type: Thermal-magnetic (LI – long-time & instantaneous)
• Interrupt Rating: ~10 kAIC @ 240V
• Application: Commercial / industrial distribution panels
• Status: Discontinued / obsolete

Common Replacements:

• Square D QOB320 3-Pole 20A Bolt-On Circuit Breaker
• Siemens BQD320 3-Pole 20A Bolt-On Breaker
• Eaton BAB3020H 3-Pole 20A Bolt-On Breaker