Breaker Boxes | McMaster-Carr

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51 Products

Square D Secondary Circuit Breaker Boxes

Connect these boxes to a main box—they do not have a main circuit breaker switch. They are single-phase, 3-wire, and can be mounted for top or bottom feed conduit connections. Also known as load centers.

NEMA 1 rated boxes are for indoor use.

NEMA 3R rated boxes are for outdoor use.

Circuit breakers meet UL 489 requirements for branch circuit protection, so they protect downstream equipment and wiring from overloads and short circuits. Circuit breakers with ground fault sensitivity will trip if they detect a current leak above 6mA. This minimizes the risk of electric shock to workers and equipment.

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

Boxes

							Cover
Number of Spaces	Current, A	Voltage	Frequency, Hz	Breakthrough Current	Mounting Style	Bus Bar Material	Attachment Style	Closure Method	Ht.	Wd.	Dp.	Specifications Met		Each
NEMA 1 Rated
2	70	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Surface	Tin-Plated Copper	Lift Off	Screws	9 1/4"	4 7/8"	3 1/4"	UL Listed	0000000	000000
8	100	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Surface	Tin-Plated Copper	Lift Off	Screws	12 5/8"	8 7/8"	3 3/4"	UL Listed	0000000	000000
12	125	120V AC/240V AC	50/60	65,000 A @ 120 V AC 65,000 A @ 240 V AC	Surface	Tin-Plated Copper	Lift Off	Screws	17 7/8"	14 1/4"	3 3/4"	UL Listed	0000000	000000
NEMA 3R Rated
6	100	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Surface	Tin-Plated Copper	Hinged	Quick-Release Latch	12 5/8"	8 7/8"	4 1/4"	UL Listed	0000000	000000
12	125	120V AC/240V AC	50/60	65,000 A @ 120 V AC 65,000 A @ 240 V AC	Surface	Tin-Plated Copper	Hinged	Quick-Release Latch	18 7/8"	14 3/4"	4 1/2"	UL Listed	0000000	000000
24	125	120V AC/240V AC	50/60	65,000 A @ 120 V AC 65,000 A @ 240 V AC	Surface	Tin-Plated Copper	Hinged	Quick-Release Latch	22"	14 3/4"	4 1/2"	UL Listed	0000000	000000

Circuit Breakers

QO Series, 1 Pole

QO Series, 2 Pole

QO Series, 3 Pole

QO 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	Breaker Box	Snap On	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	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	3/4"	UL 489, UL Listed	0000000	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	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	00000
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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	00000
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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	00000
70	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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	0000000	000000
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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	2 1/4"	UL 489, UL Listed	00000000	000000
QO Series with 6mA Ground Fault Sensitivity
1 Pole—Toggle Style
20	120V AC	50/60	10,000 A @ 120 V AC	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	000000
30	120V AC	50/60	10,000 A @ 120 V AC	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	000000
2 Pole—Toggle Style
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	000000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	000000

Square D Main Circuit Breaker Boxes

These boxes have a main circuit breaker switch and main service knockouts in the corners. They are single-phase, 3-wire, and can be mounted for top or bottom feed conduit connections. Use with Square D QO circuit breakers. Boxes are rated NEMA 1 for indoor use. Also known as load centers.

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

Boxes

Breaker Box

							Cover
Number of Spaces	Current, A	Voltage	Frequency, Hz	Breakthrough Current	Mounting Style	Bus Bar Material	Attachment Style	Closure Method	Ht.	Wd.	Dp.	Specifications Met		Each
NEMA 1 Rated
12	100	120V AC/240V AC	50/60	22,000 A @ 120 V AC 22,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Copper	Lift Off	Screws	14 7/8"	14 1/4"	3 3/4"	UL Listed	0000000	0000000
20	100	120V AC/240V AC	50/60	22,000 A @ 120 V AC 22,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Copper	Lift Off	Screws	17 7/8"	14 1/4"	3 3/4"	UL Listed	0000000	000000
30	200	120V AC/240V AC	50/60	22,000 A @ 120 V AC 22,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Copper	Lift Off	Screws	29 7/8"	14 1/4"	3 3/4"	UL Listed	0000000	00000000
40	200	120V AC/240V AC	50/60	22,000 A @ 120 V AC 22,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Copper	Lift Off	Screws	33 3/4"	14 1/4"	3 3/4"	UL Listed	0000000	00000000

Circuit Breakers

QO Series, 1 Pole

QO Series, 2 Pole

QO Series, 3 Pole

QO 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	Breaker Box	Snap On	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	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	3/4"	UL 489, UL Listed	0000000	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	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	00000
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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	00000
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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	00000
70	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	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	0000000	000000
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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	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	Breaker Box	Snap On	2 1/4"	UL 489, UL Listed	00000000	000000
QO Series with 6mA Ground Fault Sensitivity
1 Pole—Toggle Style
20	120V AC	50/60	10,000 A @ 120 V AC	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	000000
30	120V AC	50/60	10,000 A @ 120 V AC	Breaker Box	Snap On	3/4"	UL 489, UL Listed	00000000	000000
2 Pole—Toggle Style
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	000000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1 1/2"	UL 489, UL Listed	00000000	000000

Square D Homeline Secondary Circuit Breaker Boxes

Connect these boxes to a main box—they do not have a main circuit breaker switch. They are single-phase, 3-wire, and can be mounted for top or bottom feed conduit connections. Boxes are rated NEMA 1 for indoor use. Also known as load centers.

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

Boxes

Breaker Box

							Cover
Number of Spaces	Current, A	Voltage	Frequency, Hz	Breakthrough Current	Mounting Style	Bus Bar Material	Attachment Style	Closure Method	Ht.	Wd.	Dp.	Specifications Met		Each
NEMA 1 Rated
6	100	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Surface	Tin-Plated Aluminum	Lift Off	Screws	12 5/8"	8 7/8"	3 7/8"	UL Listed	0000000	000000
12	125	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Aluminum	Lift Off	Screws	17 7/8"	14 1/4"	3 3/4"	UL Listed	0000000	00000
20	125	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Aluminum	Lift Off	Screws	26"	14 1/4"	3 3/4"	UL Listed	0000000	00000

Circuit Breakers

Homeline Series, 1 Pole

Homeline
Series, 1
Tandem Pole

Homeline Series, 2 Pole

Homeline 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	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	000000
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
40	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
50	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	000000000	00000
1 Pole with Tandem Circuit—Toggle Style
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
2 Pole—Toggle Style
15	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
40	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
50	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	00000
60	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	00000
Homeline Series with 6mA Ground Fault Sensitivity
1 Pole—Toggle Style
20	120V AC	50/60	10,000 A @ 120 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	000000
2 Pole—Toggle Style
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	000000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	000000

Square D Homeline Main Circuit Breaker Boxes

With a main breaker installed and main service knockouts, these boxes are the entry point for electricity into your facility and the first step in protecting your electrical systems. They are single-phase, 3-wire, and can be mounted for top or bottom feed conduit connections. These boxes are rated NEMA 1 for indoor use. Also known as load centers.

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

Boxes

Breaker Box

							Cover
Number of Spaces	Current, A	Voltage	Frequency, Hz	Breakthrough Current	Mounting Style	Bus Bar Material	Attachment Style	Closure Method	Ht.	Wd.	Dp.	Specifications Met		Each
NEMA 1 Rated
12	100	120V AC/240V AC	50/60	22,000 A @ 120 V AC 22,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Aluminum	Lift Off	Screws	17 7/8"	14 1/4"	3 3/4"	UL Listed	0000000	0000000
24	125	120V AC/240V AC	50/60	22,000 A @ 120 V AC 22,000 A @ 240 V AC	Recessed, Surface	Tin-Plated Aluminum	Lift Off	Screws	26"	14 1/4"	3 3/4"	UL Listed	0000000	000000

Circuit Breakers

Homeline Series, 1 Pole

Homeline
Series, 1
Tandem Pole

Homeline Series, 2 Pole

Homeline 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	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	000000
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
40	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
50	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	000000000	00000
1 Pole with Tandem Circuit—Toggle Style
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	00000
2 Pole—Toggle Style
15	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
40	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	00000000	00000
50	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	00000
60	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	00000
Homeline Series with 6mA Ground Fault Sensitivity
1 Pole—Toggle Style
20	120V AC	50/60	10,000 A @ 120 V AC	Breaker Box	Snap On	1"	UL 489, UL Listed	00000000	000000
2 Pole—Toggle Style
20	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	000000
30	120V AC/240V AC	50/60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Breaker Box	Snap On	2"	UL 489, UL Listed	000000000	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 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
1"	Bryant Challenger Crouse-Hinds Cutler-Hammer (BR) General Electric Murray Siemens Square D (Homeline) Thomas & Betts Westinghouse	Snap In, Adhesive	3/8"	1"	2 9/16"	Plastic	UL 94 V-2	0000000	0000