1 Scope

1.1 These requirements cover electrically operated water treatment appliances for household, and commercial use, and industrial use. These appliances are intended for installation and use in accordance with the National Electrical Code, NFPA 70, and are rated 600 V or less.

1.2 These requirements cover appliances utilizing features that treat water through the use of cation exchange water softeners, ionization, filters, ultraviolet radiation, ozone generation, and reverse osmosis.

1.3 These requirements do not cover water treatment appliances for use with pools or spas, water distillers, aquariums, or other equipment connected to plumbing that is covered by individual requirements.

1.4 These requirements do not cover appliances for use in hazardous locations as defined in the National Electrical Code, NFPA 70.

1.5 These requirements do not cover the aesthetic effects or the effectiveness of water treatment.

Summary of Topics

This new edition of UL 979 dated August 26, 2024 incorporates editorial changes including renumbering and reformatting to align with current style, as well as the following changes in requirements:

– Revisions based on the latest version of UL 4200A; Section 9

– Editorial corrections; 38.1, 38.3, 48.7

– Replacement of the reference to the 5th Edition of UL 60335-1 by an undated reference to UL 60335-1; 30.5.2

– Addition of a reference to UL 60730-2-22; 6.16.4.1

– Updates to Section 5, Undated References, and the addition of a list of Referenced Standards; 5.2

– Clarification of the Frequency During Tests; 39.1