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 revision of UL 979 dated October 19, 2023 includes the following changes in requirements:

– Addition of UL 508A for Industrial Control Panel Enclosures used in industrial applications; 1.1 and 8.9A

– Additional requirements for Water Treatment Systems that Generate Ultraviolet Radiation; 2.34A, 2.34B, 8.8, Section 36A, 56.1A, 56.2 – 56.5, 68.10, 68.11A, 68.11B, 69.3A and 69.3B.