Control Panels

SCCR

Short-Circuit Current Rating

Definition

The maximum available fault current a control panel can safely withstand, determined by its weakest power-circuit component and required on the panel label.

NEC 409.110 requires the marking, and the panel must not be installed where available fault current exceeds it. A panel carrying a default 5 kA rating downstream of a large transformer is both a hazard and a failed inspection.

Short-Circuit Current Rating (SCCR)What a control panel’s short-circuit current rating means, how it is determined under UL 508A, why the NEC requires it on the label, and why the number is usually smaller than people expect.

SCCR

Definition

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