UL 823
Electric Heaters for Use in Hazardous (Classified) Locations
Published by UL Standards & Engagement (UL)
The CFR incorporates UL 823 by reference, which makes the edition it names part of the regulation. The CFR requires the edition it names, which may not be the newest. To enforce any other edition, the agency must publish the change in the Federal Register.
The edition the CFR requires
UL 823, Ninth Edition, revised November 15, 2007
As the CFR lists it: “UL 823, Electric Heaters for Use in Hazardous (Classified) Locations, Ninth Edition, revised November 15, 2007, (“ANSI/UL 823”)”
How to read it
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A free or purchased copy may not be the edition the CFR names; check it against the edition above. Every incorporated standard can also be inspected at the National Archives (NARA) and at the agency named in the section that lists it.
UL 823 is copyrighted by its publisher; RegKnot shows its title and the editions the CFR names, not its text. Read from the eCFR's incorporation-by-reference sections, current as of October 26, 2026. The regulation text governs. All standards the CFR requires.