What Is an Insulated Case Circuit Breaker (ICCB)?
Published: 2025-06-11 | 6 min read | Category: Technical Guide
An insulated case circuit breaker (ICCB) is a high-performance circuit breaker that combines the compact size of a molded case breaker with the maintainability and advanced protection features of an air circuit breaker. ICCBs are rated from 800A to 5,000A and are used in main switchgear applications where high fault current interruption (up to 200kAIC), field-maintainable contacts, and electronic trip units with communication capabilities are required.
ICCBs fill the gap between MCCBs (which are sealed and non-maintainable) and ACBs (which are larger and more expensive). They cost 30-50% less than equivalent air circuit breakers while offering comparable interrupting capacity and electronic protection features. Approximately 40% of US commercial main breaker applications in the 800-3000A range use ICCBs rather than ACBs.
ICCB vs. MCCB vs. ACB Comparison
| Feature | MCCB | ICCB | ACB | |---|---|---|---| | Current range | 15-2,500A | 800-5,000A | 800-6,300A | | Interrupting capacity | Up to 200kAIC | Up to 200kAIC | Up to 200kAIC | | Field maintainable | No (sealed housing) | Yes (accessible contacts) | Yes (fully open design) | | Trip unit | Thermal-magnetic or electronic | Electronic only (LSIG) | Electronic only (LSIG) | | Draw-out option | No | Yes (some models) | Yes (standard) | | Relative cost | 1x | 2-3x | 3-5x | | Typical application | Branch circuits, feeders | Main breakers, tie breakers | Main switchgear, utility ties |
**Key takeaway:** ICCBs are the optimal choice when you need main breaker protection above 800A with electronic trip features and field maintainability, but don't need the full size and cost of an air circuit breaker.
When to Use an ICCB
Use an ICCB when: the application requires 800A or higher continuous current, electronic trip protection (LSIG) is needed for coordination studies, the breaker must be field-maintainable (contact inspection and replacement without removing the breaker), and budget constraints make a full ACB impractical.
Common ICCB applications include: building main breakers (800-3000A), generator tie breakers, bus tie breakers in double-ended substations, and large feeder breakers in industrial distribution.
Common ICCB Models
| Manufacturer | ICCB Series | Rating Range | |---|---|---| | Square D | PowerPact M-frame, P-frame | 800-2500A | | Eaton | Magnum (fixed mount) | 800-4000A | | Siemens | Sentron WL (fixed) | 800-5000A | | GE | EntelliGuard | 800-5000A |
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Frequently Asked Questions
What is the difference between an MCCB and an ICCB?
An MCCB (molded case circuit breaker) has its mechanism enclosed in a molded insulating case and is not field-maintainable. An ICCB (insulated case circuit breaker) has a similar insulating case but is designed to be field-maintainable — contacts can be inspected and replaced without returning the breaker to the factory. ICCBs also typically have higher interrupting ratings and more sophisticated electronic trip units.
What amperage range do ICCBs cover?
ICCBs typically cover the range from 800A to 5000A, overlapping with the upper range of MCCBs and the lower range of air circuit breakers. Common ICCB ratings are 1600A, 2000A, 2500A, 3000A, and 4000A.
Are ICCBs draw-out or fixed?
ICCBs are available in both fixed-mounted and draw-out configurations. Draw-out ICCBs can be withdrawn from the switchgear enclosure for maintenance without de-energizing the entire bus, which is a significant advantage for critical applications.