SQUARE D
SQUARE D QOB330 30A 3 Pole 120/240V AC circuit breaker
Three-pole miniature breaker rated 30 A at 120/240 V AC with 10 kA interrupting capacity, bolt-on mounting for QO load centres
- 30 A protection for three-phase loads
- 10 kA interrupting rating handles fault current
- Bolt-on mounting fits QO panelboards
- 48 V DC rating adds application flexibility
- Pressure-plate terminals simplify wire connections
Three-pole 30 A circuit protection
The SQUARE D QOB330 is a bolt-on miniature circuit breaker rated at 30 A and 120/240 V AC for three-phase panels. It fits QO-series load centres and NQOD panelboards using a pressure-plate terminal connection.
Thermal behaviour in normal operation
The breaker carries its rated current continuously at the listed minimum operating temperature of 77 Degrees F. Its standard thermal-magnetic trip curve protects conductors without nuisance tripping during everyday load fluctuations.
Sustained overload response
Under prolonged overcurrent the thermal element trips to protect wiring, while the magnetic element provides a 10 kA interrupting rating at 120/240 V AC for short-circuit events. The 48 V DC rating does not extend AC fault-current performance.
Highlights
- 30 A protection for three-phase loads
- 10 kA interrupting rating handles fault current
- Bolt-on mounting fits QO panelboards
- 48 V DC rating adds application flexibility
- Pressure-plate terminals simplify wire connections
Specifications
| Brand | SQUARE D |
|---|
Questions about this item
How do I bolt the QOB330 into a QO load center and what step is often missed?
Align the bolt-on base with the panel bus, tighten the mounting screws to the specified torque, then press the paddle actuator until it latches — many installers forget to verify the pressure-plate terminals are fully seated on the conductors.
What maintenance or replacement will the 30 A three-pole breaker need over time?
Periodically check the bolt-on mounting hardware and pressure-plate terminal torque; if the paddle actuator becomes stiff or the 10 kA interrupting rating is exceeded during a fault, replace the breaker.
What is the first limit reached when the QOB330 runs continuously at full load?
The 30 A thermal trip curve opens the contacts before the 77 °F minimum operating temperature or the 10 kA interrupting capacity becomes a factor.
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