QOB Breakers | McMaster-Carr

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15 Products

Square D Load-Center Circuit Breakers

QOB Series, 1 Pole

QOB Series, 2 Pole

QOB Series, 3 Pole

Match these circuit breakers to Square D breaker boxes or panel boards of the same manufacturer series. They meet UL 489 requirements for branch circuit protection, so they protect downstream equipment and wiring from overloads and short circuits. Because they are thermal-magnetic, these breakers trip two different ways. They either trip when heat is generated by sustained low-level overload current or quickly when the magnetic coil senses a high-current short circuit.

Breakthrough current is the maximum current that the circuit breaker can safely stop in the event of a short circuit.

For technical drawings and 3-D models, click on a part number.

QOB Series
Current, A	Voltage	Frequency, Hz	Breakthrough Current	Mounting Location	Wire Connection Type	Wd.	Specifications Met		Each
1 Pole—Toggle Style
15	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	3/4"	UL 489, UL Listed	00000000	000000
20	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	3/4"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	3/4"	UL 489, UL Listed	00000000	00000
40	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	3/4"	UL 489, UL Listed	0000000	00000
2 Pole—Toggle Style
15	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	1 1/2"	UL 489, UL Listed	00000000	00000
20	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	1 1/2"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	1 1/2"	UL 489, UL Listed	00000000	00000
40	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	1 1/2"	UL 489, UL Listed	00000000	00000
3 Pole—Toggle Style
15	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	2 1/4"	UL 489, UL Listed	00000000	000000
20	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	2 1/4"	UL 489, UL Listed	00000000	000000
30	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	2 1/4"	UL 489, UL Listed	00000000	000000
40	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	2 1/4"	UL 489, UL Listed	00000000	000000
50	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	2 1/4"	UL 489, UL Listed	00000000	000000
60	120V AC/240V AC/48V DC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC 5,000 A @ 48 V DC	Panel Board	Screw-Clamp Terminals	2 1/4"	UL 489, UL Listed	00000000	000000

Filler Plates for Circuit Breaker Boxes

Conceal live electrical components in circuit breaker boxes to prevent injury and damage. These filler plates snap into panel openings. They also have an adhesive strip, so they don’t move when you take the panel cover off.

For technical drawings and 3-D models, click on a part number.

For Panel Cutout Wd.	For Manufacturer (Series)	Mount Type	Ht.	Wd.	Dp.	Material	Specifications Met		Each
3/4"	Square D (QO) Square D (QOB)	Snap In, Adhesive	3/8"	11/16"	2 9/16"	Plastic	UL 94 V-2	0000000	00000