Breaker Box Breakers | McMaster-Carr

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54 Products

Square D Load-Center Circuit Breakers

QO Series, 1 Pole

QO Series, 2 Pole

QO Series, 3 Pole

Homeline Series, 1 Pole

Homeline
Series, 1
Tandem Pole

Homeline Series, 2 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.

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.

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

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
Homeline Series
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	00000
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

Siemens Load-Center Circuit Breakers

1 Pole

2 Pole

Use with Siemens EQ series breaker boxes. These circuit breakers 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, they trip two different ways. They either trip when heat is generated slowly by consistent 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.

1 Pole—Toggle Style
Current, A	Voltage	Frequency, Hz	Breakthrough Current	Wire Connection Type	Wd.	Specifications Met		Each
15	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1"	UL 489	0000000	000000
20	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1"	UL 489	0000000	00000
30	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1"	UL 489	0000000	00000
2 Pole—Toggle Style
15	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	2"	UL 489	0000000	00000
20	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	2"	UL 489	0000000	00000
30	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	2"	UL 489	0000000	00000
40	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	2"	UL 489	0000000	00000
50	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	2"	UL 489	0000000	00000
60	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	2"	UL 489	0000000	00000
70	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	2"	UL 489	000000	00000

Cutler-Hammer Load-Center Circuit Breakers

1 Pole

2 Pole

Install these circuit breakers into Cutler-Hammer CH series breaker boxes. They meet UL 489 requirements for branch circuit protection, so they protect downstream equipment and wiring from overloads and short circuits. Because these circuit breakers are thermal-magnetic, they trip two different ways. They either trip when heat is generated slowly by consistent 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.

1 Pole—Toggle Style
Current, A	Voltage	Frequency, Hz	Breakthrough Current	Wire Connection Type	Wd.	Specifications Met		Each
15	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	3/4"	UL 489	0000000	000000
20	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	3/4"	UL 489	0000000	00000
30	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	3/4"	UL 489	0000000	00000
2 Pole—Toggle Style
15	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1 1/2"	UL 489	0000000	00000
20	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1 1/2"	UL 489	0000000	00000
30	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1 1/2"	UL 489	0000000	00000
40	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1 1/2"	UL 489	0000000	00000
50	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1 1/2"	UL 489	0000000	00000
60	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1 1/2"	UL 489	0000000	00000
70	120V AC/240V AC	60	10,000 A @ 120 V AC 10,000 A @ 240 V AC	Screw-Clamp Terminals	1 1/2"	UL 489	000000	00000