Technical information

3. Short Circuit Current Rating
3.1 Short Circuit Current Rating
3.1.1 National Electric Code Changes Overview
National Electrical Code Introduces Article 409 for Industrial Control Panels
In 2005, the National Electrical Code (NEC) introduced Article 409 for Industrial
Control Panels requiring that panel builders and original equipment
manufacturers (OEM) analyze and mark their panels with short circuit current
ratings (SCCR).
Why Article 409 was developed?
Historically, industrial control panels have been
evaluated under several different NEC articles, which
have led to inconsistencies.Article 409 provides
common construction and installation requirements. It
also establishes a marking requirement for short
circuit current ratings of industrial control panels.
The fine print note of NEC Article 409.110 references
UL508A, Supplement SB as an approved method to
evaluate the short circuit current ratings of their
panel. As individual states adopt the 2005 Edition of
the NEC, a thorough understanding UL508A,
Supplement SB is essential.
INDUSTRIAL MACHINERY
94
NEC 2005 Code Book
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