125A Breakers | McMaster-Carr

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48 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
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	0000000
NEMA 3R Rated
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	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	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
15, 20, 30, 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	000000	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
20, 30	120V AC	50/60	10,000 A @ 120 V AC	Breaker Box	Snap On	3/4"	UL 489, UL Listed	0000000	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
20, 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	0000000	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.

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

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	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	000000
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.

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

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
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	0000000

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

High-Power Circuit Breakers

Protect an area of a facility that has high-powered equipment. These circuit breakers are also known as molded case circuit breakers. They meet UL 489 requirements for branch circuit protection. Because these breakers are thermal-magnetic, they trip two ways. They either trip when heat is generated slowly by consistent low-level overload current, or they trip quickly when the magnetic coil senses a high-current short circuit. A switch lets you adjust when these breakers magnetically trip, so you don't need to replace them as your application changes. These breakers have internal accessory slots to fit shunt trips, auxiliary contacts, and undervoltage trips, saving space in your setup.

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

Shunt trips receive a signal from equipment to trip your circuit breaker in situations other than overload or short circuit conditions. For example, use them with a smoke detector to shut off power to a system in the event of a fire. 30A to 250A breakers can only have one shunt trip or undervoltage trip installed. 400A to 600A breakers can accommodate one shunt trip and one undervoltage trip at the same time.

Auxiliary contacts send a signal to other equipment when the circuit trips. They can activate a warning light, initiate a shutdown, or start a backup power source. Multiple auxiliary contacts can be used within one circuit breaker and can be placed in any of the accessory slots.

Undervoltage trips protect equipment from operating with less than their intended voltage by tripping a circuit breaker when the supply voltage drops below a set level. 30A to 250A breakers can only have one shunt trip or undervoltage trip installed. 400A to 600A breakers can accommodate one shunt trip and one undervoltage trip at the same time.

Install handles on the front cover of an electrical cabinet to turn these breakers on, off, or reset them without having to open the cabinet. Yet, these handles won’t prevent you from opening the electrical cabinet normally. You can also lock the handles in the on or off position with a padlock (not included) to prevent unauthorized changes to the circuit breaker.

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

Circuit Breakers

Circuit Breaker

3 Pole—Toggle Style
Current, A	Voltage	Frequency, Hz	Breakthrough Current	Inrush Current Setting, A	Mounting Location	For DIN Rail Size, mm	Mount Type	Ht.	Wd.	Dp.	Temp. Range, °F	Specifications Met		Each
125	480V AC/600YV AC/600V DC	50/60	65,000 A @ 240 V AC 25,000 A @ 480 V AC 14,000 A @ 600 V AC 14,000 A @ 125 V DC 50,000 A @ 250 V DC 50,000 A @ 500 V DC 50,000 A @ 600 V DC	625, 750, 875, 1,000, 1,125, 1,250	DIN Rail	35	Screw On	5.5"	3"	3"	-10° to 155°	UL 489, UL Listed, CE Marked, IEC 60947-2, IEC 81346-2	0000000	000000000

Shunt Trips

Shunt Trip

Voltage	Current	Frequency, Hz	Wire Connection Type	Ht.	Wd.	Dp.	Temp. Range, °F	Specifications Met		Each
110-127V AC	7.4 A @ 110 V AC	50/60	Screw-Clamp Terminals	2.56"	0.85"	1.23"	-10° to 155°	UL 489, UL Listed, IEC 60947-2	0000000	0000000

Auxiliary Contacts

Auxiliary Contact

Voltage	Current, A	Frequency, Hz	Industry Designation	No. of Circuits Controlled	Switch Starting Position	Wire Connection Type	Ht.	Wd.	Dp.	Temp. Range, °F	Specifications Met		Each
24-300V AC/24-250V DC	6	50/60	DPST	2	1 Off (Normally Open) and 1 On (Normally Closed)	Screw-Clamp Terminals	2.57"	0.28"	1.36"	-10° to 155°	UL 489, UL Listed, IEC 60947-2	0000000	0000000

Undervoltage Trips

Undervoltage Trip

Voltage	Current	Frequency, Hz	Wire Connection Type	Ht.	Wd.	Dp.	Temp. Range, °F	Specifications Met		Each
120-127V AC	0.01 A @ 120 V AC	50/60	Screw-Clamp Terminals	2.56"	1.01"	1.13"	-10° to 155°	UL 489, UL Listed, IEC 60947-2	0000000	0000000

Handles

Handle

For Circuit Breaker Current, A	Ht.	Wd.	Projection	Mounting Fasteners Included	For Max. Padlock Shackle Dia.	Padlock Included	Temp. Range, °F	Environmental Rating	Specifications Met		Each
30, 60, 100, 125	2.95"	2.95"	2.16"	Yes	3/8"	No	-10° to 155°	IP65, NEMA 4X, NEMA 12	IEC 60947-2	0000000	0000000