SQUARE D
SQUARE D QOB320 Miniature Circuit Breaker 20A 3 Pole 120/240V AC
Three-pole 20 A miniature breaker for 120/240 V AC and 48 V DC panels, bolt-on mounting with 10 kA interrupting rating
- Protects three-phase circuits with 20 A rating
- Interrupts up to 10 kA at 120/240 V AC
- Bolt-on mounting fits QO and NQOD panelboards
- Pressure-plate terminals accept wire without lugs
- Operates from 77 °F minimum temperature
Three-Pole 20 A Protection
This Square D QOB320 miniature circuit breaker provides three-pole overload and short-circuit protection for 20 A branch circuits in compatible QO load centres. It is intended for electricians and facility managers who need a bolt-on device rated for 120/240 V AC three-phase distribution. The paddle actuator gives clear on/off indication during maintenance or emergency shutdown.
10 kA Interrupting Limit
The breaker carries a maximum AIR rating of 10 kA at 120/240 V AC, so it must only be installed where the available fault current does not exceed that value. It also carries a 48 V DC rating for limited low-voltage control circuits. The pressure-plate terminals accept conductors sized for the 100 A frame, and the minimum operating temperature is 77 °F.
Replaces Standard Single-Pole Breakers
This unit replaces three separate single-pole breakers when a common-trip mechanism is required for three-phase loads such as motors or heating elements. The jump is worth it when code or equipment documentation calls for simultaneous disconnection of all phases. It is not suited for panels outside the QO series or for applications demanding higher interrupting capacity.
Highlights
- Protects three-phase circuits with 20 A rating
- Interrupts up to 10 kA at 120/240 V AC
- Bolt-on mounting fits QO and NQOD panelboards
- Pressure-plate terminals accept wire without lugs
- Operates from 77 °F minimum temperature
Specifications
| Brand | SQUARE D |
|---|
Questions about this item
Should I choose the 20 A three-pole version or a different QO breaker?
Select the 20 A three-pole QOB320 when your branch circuit requires 20 A protection across three phases in a Square D QO or NQOD panelboard; other amperages or pole counts serve different load profiles.
What does the 120/240 V AC rating mean once the breaker is installed?
It means the breaker will safely interrupt faults on a three-phase system where phase-to-phase voltage is 240 V and phase-to-neutral is 120 V, matching standard North American panelboards.
How does the bolt-on mounting and QO series interface affect installation?
The bolt-on design secures the breaker directly to the panelboard bus, and the QO series keying ensures it only fits Square D QO or NQOD load centers, preventing cross-brand mismatches.
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