A new supplement to the UL codes dictates all low-voltage control panels be rated for short-circuit current.
NEC adoption by state
Though the NEC is the standard for electrical practices throughout the U.S., each state or local jurisdiction must ratify adoption of the current version. Some state regulations specify the "current standard" as the official state version. Others require approval by their local governing body. These are the current levels of the Code adopted by each state as of March 2006. UL approval for industrial control panels demands compliance with UL 508A Supplement SB in all states as of April 25, 2006.
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