How many faults can a breaker interrupt?

FA121242

14/05/2020

Issue:  
What number of short circuits or faults are Square D breakers rated to interrupt?

Product line:  
Circuit breakers

Environment: 
UL489 listed circuit breakers

Resolution:  
This is a summary of testing required for breakers to be UL489 compliant.  Requirements vary so please refer to UL489 for complete details.

At Rated Current (handle rating):  
Frame Size Amperes Full Load Operations No Load Operations Total Operations
0-100 6,000 4,000 10,000
101-225 4,000 4,000 8,000
226-600 1,000 5,000 6,000
601-800 500 3,000 3,500
801-2500 500 2,000 2,500
2501-6000 400 1,100 1,500

Overload:  
The circuit breaker is operated making and breaking 600% of its continuous current rating, but not less than 150 ampere. 
For circuit breakers through 1600 ampere, the number of 600% operations is 50
For larger circuit breakers through 4000 ampere, the number of operations is 25.

Short Circuit: 
For circuit breakers rated 240 Vac and higher, two 10 kA short circuit tests per pole and one test with all poles connected in series is performed.  For example, a 3-pole circuit breaker receives seven short circuit tests.

High Available Fault Current Tests (twice at interrupting rating):  
After qualifying a set of circuit breakers to the standard tests, a manufacturer can have additional circuit breaker samples tested on higher than standard available fault currents.