ZINSCO QB24-3030 U 30A 240V 3-pole Molded Case Circuit Breaker QB243030

Description:

The Zinsco QB24-3030 U (also referenced as QB243030) is a 30 Amp, 3-pole molded case circuit breaker designed for use in Zinsco / GTE Sylvania panelboards. It operates on 240V systems and utilizes a thermal-magnetic trip mechanism (Magnatrip type) to protect against overloads and short circuits. This breaker is part of the QB24 series and features a bolt-on mounting design for a secure electrical connection to the panel bus. It is a legacy component and has been discontinued by the manufacturer.

Applications:

The Zinsco QB24-3030 breaker is commonly used in commercial and industrial electrical systems for three-phase branch or feeder circuits requiring 30A protection. Typical applications include motor control panels, machinery circuits, pumps, and compressors. It is installed in Zinsco bolt-on panelboards and is now primarily used for maintenance or replacement of existing systems. 

Technical Specifications:

• Manufacturer: Zinsco / GTE Sylvania / Challenger
• Model / Part Number: QB24-3030 U / QB243030
• Product Type: Molded Case Circuit Breaker (Bolt-On)
• Poles: 3-Pole
• Current Rating: 30 Amps
• Voltage Rating: 240 VAC
• Phase: 3-phase
• Interrupt Rating: ~10 kAIC @ 240V
• Trip Type: Thermal-magnetic (LI – long-time & instantaneous)
• Mounting: Bolt-on (QB series)
• Function: Overcurrent and short circuit protection
• Status: Obsolete / discontinued

Common Replacements:

• Square D QOB330 3-Pole 30A Bolt-On Circuit Breaker
• Siemens BQD330 3-Pole 30A Bolt-On Breaker
• Eaton BAB3030H 3-Pole 30A Bolt-On Breaker