SQUARE D
SQUARE D QOB270 Miniature Circuit Breaker 70A 2 Pole 120/240V AC
A bolt-on miniature circuit breaker rated 70 A at 120/240 V AC with a 10 kA interrupting capacity for QO load centres
- 70 A protection for 120/240 V AC circuits
- 10 kA interrupting capacity at rated voltage
- Bolt-on mounting fits QO load centres
- 48 V DC rating adds versatility
- Compact 3.12 x 1.5 x 2.91 in frame size
QOB270 70 A Bolt-On Breaker
The SQUARE D QOB270 is a 70 A miniature circuit breaker built for QO series load centres. It protects single-phase 120/240 V AC circuits and carries a 10 kA interrupting rating at that voltage. The two-pole paddle actuator mounts by bolt-on terminals into compatible NQOD panelboards. It suits electricians and maintenance teams fitting or replacing branch-circuit protection in commercial or light-industrial boards.
Thermal and Electrical Behaviour
The device is rated for a minimum operating temperature of 77 °F and a maximum DC voltage of 48 V. Its 100 A frame size and standard breaker type define the thermal-magnetic trip curve for normal loading. No active cooling or fan is present; heat dissipates through the bolt-on lugs and the 3.12 in by 1.5 in by 2.91 in moulded housing during typical operation.
Included Lugs and Panel Compatibility
Factory-fitted terminal lugs accept the conductor sizes specified for the 100 A frame, removing the need for separate lug kits. The bolt-on mounting style locks the breaker securely into Square D NQOD panelboards, ensuring positive contact without additional hardware. No software, configuration tools or accessories beyond the lugs are supplied or required for installation.
Highlights
- 70 A protection for 120/240 V AC circuits
- 10 kA interrupting capacity at rated voltage
- Bolt-on mounting fits QO load centres
- 48 V DC rating adds versatility
- Compact 3.12 x 1.5 x 2.91 in frame size
Specifications
| Brand | SQUARE D |
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Questions about this item
How do I bolt the QOB270 into a QO panelboard and which step is often missed?
Align the breaker with the panel bus, press firmly until the bolt-on feet seat, then torque the mounting bolt to spec; the step often missed is confirming the bolt is fully tightened after the breaker clicks in.
What maintenance or replacement will the QOB270 need over time?
No scheduled maintenance is required; replace the breaker if it trips repeatedly without overload, shows discoloration at the lug terminals, or fails to reset cleanly after a fault.
What is the first limit reached under sustained load on the QOB270?
The 70 A thermal trip curve is the first limit; continuous operation above 70 A will cause the breaker to open, while the 10 kA interrupting rating only applies during short-circuit faults.
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