Switchgear Rating Calculator

Determine switchgear ratings and verify interrupting capacity per NEC 110.9.

Equipment Type

System Voltage (V)

System Type

Available Fault Current (kA) At equipment location

X/R Ratio Typical: 4-25

Continuous Current (A)

Ambient Temperature

Short Time Rating Required

Standard AIC Ratings

Equipment	Typical AIC (kA)
Residential Panel	10 - 22 kA
Commercial MCCB	14 - 65 kA
Industrial MCCB	25 - 100 kA
ICCB	42 - 100 kA
LVPCB (Draw-out)	65 - 200 kA
MV Switchgear	20 - 63 kA

Typical Frame Sizes (480V MCCB)

Frame	Max Amps	AIC Options
100A	100A	14-65 kA
250A	250A	22-65 kA
400A	400A	25-100 kA
800A	800A	42-100 kA
1600A	1600A	42-100 kA
2500A	2500A	65-100 kA

NEC Requirements for Switchgear

NEC 110.9 - Interrupting Rating

Equipment must have interrupting rating sufficient for available fault current
Series ratings allowed per NEC 240.86
Must be marked with AIC rating
Consider motor contribution to fault

NEC 110.10 - Circuit Impedance

Equipment must withstand fault current without damage
Verify short-circuit current rating (SCCR)
Consider component damage threshold
Coordinate with upstream protection