Molded & Insulated Case Circuit Breakers

Currently shopping by:
  • Manufacturer: Square D
  • Amperage: 3000 or 4000
Remove Filter
While our website showcases a large assortment of our products, it does not reflect the complete inventory of products currently available. For real-time availability and to ensure we can meet your specific needs, please contact our sales team at 1-800-328-1842. New products arrive daily and our knowledgeable staff are happy to assist you in locating the exact item(s) you need.

SED364000LSGS1A8 Square D Breaker 4000 Amp 600 VAC

Square D SED364000LSGS1A8 breaker; 4000 amp with 3000 amp rating plug cat.#ARP075, shunt trip, micro logic full function series B with LSIG, ground fault, 600 VAC, used tested with report.
SKU: MCCB1377

SED363000LSGES5D4 Square D Breaker 3000 Amp 600 VAC E/O

Square D SED363000LSGES5D4 breaker; series 3, 3000 amp, 600 volt AC, 3 pole. With 3000 amp rating plug cat.#ARP100, micro logic with LSIG functions, ground fault, shunt trip- 24 VDC, with 4 auxiliary switches- 125 VDC/ 120 VAC, 50/60 HZ, integral ground fault- 120 VAC, alarm switch- 120/240 VAC, electrically operated (E/O), used tested with report.
SKU: MCCB1359

SED363000LSES504 Square D Breaker 3000 Amp 600 VAC E/O D/O

Square D SED363000LSES504 breaker; series 3A, 3000 amp with 3000 amp rating plug cat.#RP100 with shunt trip 24 VDC, shunt close, 120 VAC, 50/60 HZ with alarm switches, 120/240 VAC, 50/60 HZ with 4 auxiliary switches 125 VDC, 120 VAC, 50/60 HZ, 600 VAC, electrically operated (E/O), spring charging motor, 120 VAC, 50/60 HZ spring charge contact 125-250 VAC, 50/60 HZ, draw-out (D/O), used tested with report.
SKU: MCCB1272

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker: 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit, LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 VAC, .5A/.25A @125/250 VDC, overcurrent trip switch- 10A/240 VAC, LT alarm- .1A/240 VAC, shunt trip- 24 VDC, closing release- 24 VDC, under voltage release- 24 VDC, motor & charged switch- 24/30 VDC, neutral sensor, electrically operated (E/O)- 24/30 VDC, fixed-mount (F/M), neutral sensor, used tested with report.
SKU: MCCB1678

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit, LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 VAC, .5A/.25A @ 125/250 VDC, overcurrent trip switch- 10A/240 VAC, LT Alarm- .1A/240 VAC, shunt trip- 24 VDC, closing release- 24 VDC, under voltage release- 24 VDC, motor charged switch- 24/30 VDC, neutral sensor, electrically operated (E/O)- 24/30 VDC, fixed-mount (F/M), used tested with report.
SKU: MCCB1684

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit- LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 Volt AC, .5A/.25A @125/250 VDC, overcurrent trip switch- 10A/240 VAC, LT Alarm- .1A/240 VAC, shunt trip- 24 VDC, closing release- 24 VDC, under voltage release- 24 VDC, motor charged switch- 24/30 VDC, neutral sensor, electrically operated (E/O)- 24/30 VDC, fixed-mount (F/M), used tested with report.
SKU: MCCB1685

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit with LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 VAC, .5A/.25A @125/250 VDC, overcurrent trip switch- 10A/240 VAC, LT Alarm- .1A/240 VAC, shunt trip- 24 VDC, closing release- 24 VDC, under voltage release- 24 VDC, motor & charged switch- 24/30 VDC, neutral sensor, electrically operated (E/O)- 24/30 VDC, fixed-mount (F/M), neutral sensor, used tested with report.
SKU: MCCB1687

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit, LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 VAC, .5A/.25A @125/250 VDC, overcurrent trip switch- 10A/240 VAC, LT Alarm- .1A/240 VAC, shunt trip- 24 VDC, closing release- 24 VDC, under voltage release- 24 VDC, motor & charged switch- 24/30 VDC, neutral sensor, electrically operated (E/O)- 24/30 VDC, fixed-mount (F/M), neutral sensor, used tested with report.
SKU: MCCB1689

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit- LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 VAC, .5A/.25A @125/250 VDC, overcurrent trip switch- 10A/240 VAC, LT Alarm- .1A/240 VAC, shunt trip- 24 VDC, closing release- 24 VDC, under voltage release- 24 VDC, motor charged switch- 24/30 VDC, neutral sensor, electrically operated (E/O)- 24/30 VDC, fixed-mount (F/M), used tested with report.
SKU: MCCB1691

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit, LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 Volt AC, .5A/.25A @125/250 Volt DC, overcurrent trip switch- 10A/240 Volt AC, LT Alarm- .1A/240 Volt AC, shunt trip- 24 Volt DC, closing release- 24 Volt DC, under voltage release- 24 Volt DC, motor charged switch- 24/30 Volt DC, neutral sensor, electrically operated (E/O)- 24/30 Volt DC, fixed-mount (F/M), neutral sensor, used tested with report.
SKU: MCCB1693

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC F/M E/O

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit cat# 54766, LSIG functions, ground fault, auxiliary switches, LT alarm- 240 VAC, shunt release- 24 VDC, motor operator- 24/30 VDC, closing release- 24 VDC, under voltage release- 24 VDC, overcurrent- 10A/240 VAC, current neutral sensor cat# 685 527 A, fixed-mount (F/M), electrically operated (E/O), used tested with report.
SKU: MCCB1698

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC F/M E/O

Square D MP30H1 Masterpact circuit breaker: 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit cat# 54766 with LSG functions, ground fault, auxiliary switches, LT Alarm- 240 VAC, shunt release- 24 VDC, motor operator- 24/30 VDC, closing release- 24 VDC, under voltage release- 24 VDC, overcurrent- 10A/240 VAC, current neutral sensor cat# 685 527 A, fixed-mount (F/M), electrically operated (E/O), used tested with report.
SKU: MCCB1699

Square D Masterpact MP30H1 Circuit Breaker 3000 Amp 600 VAC E/O F/M

Square D MP30H1 Masterpact circuit breaker; 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit- LSIG functions, ground fault, auxiliary switches- 10A/6A/3A @ 240/480/600 VAC, .5A/.25A @125/250 VDC, overcurrent trip switch- 10A/240 VAC, LT Alarm- .1A/240 VAC, shunt trip- 24 VDC, closing release- 24 VDC, under voltage release- 24 VDC, motor charged switch- 24/30 VDC, neutral sensor, electrically operated (E/O)- 24/30 VDC, fixed mount (F/M), used tested with report.
SKU: MCCB1692

Square D Masterpact NW40H Circuit Breaker 4000 Amp 600 VAC E/O D/O

Square D NW40H MasterPact circuit breaker: cat.#YL3KKR64A3DFBBWPCAT, 4000 amp frame, 600 volt AC, three pole, 4000 amp rating plug, Micro logic 6.0P trip with LSIG functions, ground fault, mod bus, spring charging motor- 100-130 VAC, shunt trip- 24-30 VAC/DC, closing coil -24-30 VAC/DC, 2nd OC trip switch, electrically operated (E/O), draw-out (D/O), used tested with report.
SKU: MCCB1528

Square D Masterpact NW40H2 Circuit Breaker 4000 Amp 600 VAC E/O D/O

Square D NW40H2 MasterPact circuit breaker: cat.# YA5KKR63A3SFBFXXXX, 4000 amp frame, 600 volt AC, three pole, 4000 amp rated. 85kA @ 480V, Micrologic 5.0 P trip unit with LSI functions, Modbus, spring charging motor- 100-130 Volt AC/DC, shunt trip- 24-30 Volt AC/DC, closing coil - 100-130 VAC/DC, electrically operated (E/O), draw-out (D/O), used tested with report.** Small Chip in Bottom RT. Corner**.
SKU: MCCB1506

Square D MasterPact NW40H2 Circuit Breaker 4000 Amp 600 VAC M/O D/O

Square D NW40H2 MasterPact circuit breaker; cat # YA5KJR44A9SXXXXXXA, 4000 amp, 600 volt AC, three pole. With Micrologic 6.0 amp trip unit, LSIG functions, ground fault, 3200 amp rating plug, key interlock, manually operated (M/O), draw-out (D/O), used tested with report.
SKU: MCCB1930
Contact us for pricing:

Square D MasterPact NW40H2 Circuit Breaker 4000 Amp 600 VAC M/O D/O

Square D NW40H2 MasterPact circuit breaker; cat# YA5KJR44A9SXFXXXXA, 4000 amp, 600 volt AC, three pole. With Micrologic 6.0 amp trip unit, LSIG functions, ground fault, 3200 amp rating plug, key interlock, manually operated (M/O), draw-out (D/O), used tested with report.
SKU: MCCB1931
Contact us for pricing:

Square D SED363000LSA4 Circuit Breaker 3000A 600 VAC M/O D/O

Square D SED363000LSA4 Circuit Breaker; 3000 amp, 600 volt AC, 3 pole. With micrologic standard series B, LSI functions, ARP100 rating plug, manually operated (M/O), draw-out (D/O), used tested with report.
SKU: MCCB1989
Contact us for pricing:

Square D MasterPact MP30H1 Breaker 3000A 600 VAC

Square D MasterPact MP30H1 Breaker: 3000 amp, 600 volt AC, 3 pole. With STR 58 U trip unit with LSIG functions, ground fault, 3000 amp rating plug cat# 54766, shunt trip-24 VDC, (2) motor & charged switch-24 VDC, closing release-24 VDC, under voltage release- 24 VDC, mounting carriage, test report, used tested with report.
SKU: MCCB1959
Contact us for pricing:

Square D SEF364000LSGZ Electronic Trip Circuit Breaker 4000 Amp 600 Volt AC M/O F/M

Square D SEF364000LSGZ Electronic Trip Circuit Breaker; 4000 amp, 600 volt AC, 3 pole. With micrologic full function series B trip unit, LSIG functions, ground fault, rating plug cat# ARP100, manually operated (M/O), fixed-mount (F/M). Used tested with report.
SKU: MCCB2051
$37,500.00

New, Used, and Tested Molded & Insulated Case Circuit Breakers

EMSCO has been specializing in used and refurbished molded & insulated case circuit breakers for over 72 years.


Why Choose EMSCO for Molded Case or Insulated Case Circuit Breakers?

Want to match and replace your existing breakers? End the hassle of retrofitting your electrical system. Our extensive inventory includes a variety of Molded Case Circuit Breakers (MCCBs) and Insulated Case Circuit Breakers that are designed to seamlessly match and replace your existing breakers by brand, amp rating, voltage, frame size, or model.

New and Refurbished Products in Stock

We understand that budgets and preferences differ, so we give you the option of selecting between new and refurbished MCCBs or Insulated Case Breakers, both of which are readily available in our inventory. Choose brand-new circuit breakers for maximum performance and longevity, or look into our refurbished options, which have been rigorously tested and reconditioned to meet industry standards.

Popular Brands and Common Configurations

Our shelves are stocked with breakers from the most trusted and popular brands in the industry, ensuring you have access to dependable products. You'll find common configurations, such as different frame sizes and voltage ratings, making it simple to find the right circuit protection for your application.

Avoiding Costly Operational Downtime

Downtime can be an expensive situation. Our circuit protection products are designed for high performance and durability. You can avoid costly operational downtime due to electrical failures by using our fully-tested Molded Case or Insulated Case breakers. Our products provide reliable power and superior equipment protection.

Electrical Testing Equipment Certifying Quality and Performance

When it comes to the dependability and safety of your electrical systems, we leave nothing to chance. Our breakers are rigorously tested using current testing equipment to ensure that they meet or exceed industry standards. This ensures that your electrical installations are safe and efficient.

  • Overcurrent Protection: We verify that your breakers provide accurate overcurrent protection, guaranteeing the safety of your electrical systems.
  • Trip Time: We measure the time it takes for breakers to respond to overcurrent conditions, ensuring it operates within the specified trip time.
  • Short-Circuit Withstand Capacity: Our testing evaluates the breaker’s ability to withstand short-circuit currents, preventing damage and maintaining safety.
  • Interrupting Capacity: We determine the MCCB's capability to interrupt fault currents, ensuring the utmost protection for your electrical system.

Molded Case Circuit Breaker Specifications

A sample table of ampere ratings, corresponding voltage ratings, and frame sizes for molded case circuit breakers is shown below. Please keep in mind that frame sizes and ratings can differ between manufacturers and models. For precise details on a specific MCCB, always refer to the manufacturer's specifications.

Frame Size

Ampere Rating

Voltage Rating

A

15A

120V, 240V

A

20A

120V, 240V

B

30A

120V, 240V, 480V

B50A120V, 240V, 480V
C60A240V, 480V
C100A240V, 480V
D150A240V, 480V, 600V
D200A240V, 480V, 600V
E250A240V, 480V, 600V
E300A240V, 480V, 600V
F400A240V, 480V, 600V
F600A240V, 480V, 600V
G800A240V, 480V, 600V
G1200A240V, 480V, 600V
H1600A240V, 480V, 600V

This table is a sample representation of frame sizes, ampere ratings, and voltage ratings for Molded Case Circuit Breakers, not an exhaustive list.

Molded case circuit breakers (MCCBs) and insulated case circuit breakers (ICCBs) are two distinct types of circuit protection devices used in electrical systems. Both serve the purpose of interrupting electrical currents in case of faults or overloads, but they differ in construction, application, and performance characteristics. Need Help Now? Call 800-328-1842.