UL 174:2021 PDF Download

UL 174:2021 Standard for Household Electric Storage Tank Water Heaters provides requirements for household electric storage tank water heaters with a maximum rating of 600 volts and 12 kilowatts. These requirements are applicable to water heaters that are installed in accordance with the National Electrical Code, NFPA 70, as well as model plumbing and mechanical codes.

However, it is important to note that there are certain types of water heaters that are not covered by this standard. Immersed electrode, side arm, booster, instantaneous, and immersion type water heaters, as well as water heating portions of water dispensing appliances, are excluded from the scope of this standard. Additionally, water heaters with a tank capacity of less than 1 gallon or more than 120 gallons are not covered.

Furthermore, electric booster water heaters, electric commercial storage tank water heaters, and remote control assemblies for such heaters that are rated 600 volts or less fall under a different standard, UL 1453. Permanently installed electric water heaters for heating water supplied to pools or tubs, where swimming, bathing, or immersion of persons is involved, are covered by the Standard for Electric Water Heaters for Pools and Tubs, UL 1261. Water heaters rated 600 volts or less with a tank capacity of less than 1 gallon are covered under the Standard for Electric Heating Appliances, UL 499.

In the case of water heaters intended for use in hazardous locations, compliance with the requirements of UL 174 is necessary, but further examination and testing must be conducted to determine their acceptability for the intended use.