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New Standard Edition for Household and Electrical Appliances

UL 60335-2-40, Ed. 4, is scheduled for publication in November from UL Standards & Engagement and will affect certain requirements for electrical heat pumps, air conditioners and dehumidifiers.

Row of air conditioning units on brick driveways.

January 10, 2023

The fourth edition of UL 60335-2-40, the Standard for Household and Similar Electrical Appliances – Safety – Part 2-40: Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers, was published recently from UL Standards and Engagement. The fourth edition is intended for use in conjunction with the sixth edition of UL 60335-1, the Standard for Safety of Household and Similar Appliances, Part 1: General Requirements, dated Oct. 31, 2016.

New updates

Some of the key changes for the new edition of UL 60335-2-40 include:

  • Leakage current and electric strength at operating temperature – Changes in Article 210.8(F), Clause 13 of NFPA 70®, the National Electrical Code®, allow for alternative safety measures due to inoperability with code-required ground fault circuit interrupters (GFCIs). For motor-operated and combined, permanently connected, stationary, class I appliances, which are appliances accessible to the general public, leakage current is replaced with touch current as defined in IEC 60990 and measured using the IEC 60990 Figure 5 measuring network. The touch current shall not exceed 3.5 mA unless other conditions are met, such as one of the following:
    • A larger terminal for the protective earthing terminal is used.
    • A second connecting terminal for an additional protective earthing conductor is provided.
    • A monitoring device interrupts all supply conductors when it detects an open circuit on the protective earthing conductors.
  • Annex LL (normative), refrigerant detection systems for flammable refrigerants – This annex was rewritten and no longer references IEC 60079-29-1 for the conformity of flammable gas detectors. When the refrigerant detection system (RDS) senses a concentration of refrigerant gas that is 25% of the lower flammability limit (LFL) for that gas, the RDS must initiate a system response to mitigate the potential hazard as required by Clause 22 and Annex GG. When the RDS incorporates a group controller, it must also comply with the requirements of Annex 101.DVN for information technology equipment (ITE) cooling appliances.

    In addition, refrigerant detection systems cannot have false or nuisance trips, or “poisoning damage” from typical household and commercial chemicals encountered in typical environmental conditions, such as isopropyl alcohol, ammonia, acetone and others found in table LL.3DV. After exposure to the gases in Table LL.3DV, the RDS must initiate a system response at the detection threshold limit value within a tolerance of ± 5.0 % of the LFL, but not lower than 1.0 % of the LFL.

    Finally, informative Annex 101.DVM, which serves as a supplement to Annex LL, describes examples of acceptable compliance paths for providing data and evidence to substantiate the claimed life of a refrigerant sensor as required by Clauses LL.7.2DV of Annex LL.DV.
  • Annex 101.DVN (normative), additional requirements for appliances intended for information technology equipment (ITE) applications and utilizing A2L refrigerants – This new section is specific to applications involving ITE. The covered equipment is not accessible to the general public and is a fixed or stationary appliance. The requirements align with the installation requirements of ASHRAE 15. Several mitigation strategies are acceptable in the Annex, including continuous air, air turned on by a refrigerant leak detector, and safety shut-off valves.

    This annex does not apply to cooling systems covered under UL 62368-1, the Standard for Audio/Video, Information and Communication Technology Equipment – Part 1: Safety Requirements, which specifically covers ITE and does not apply to cooling appliances intended to only have the refrigerant-containing components located within machinery rooms or other spaces that are not ITE areas.

How UL Solutions is making an impact

As a safety science leader, UL Solutions facilitates the development of standards such as UL 60335-2-40, which establishes requirements for protection against a variety of hazards that can result from normal use — electrical, mechanical, thermal, fire, radiation — as well as certain abnormal situations that may also occur. UL Solutions helps establish consistent requirements to address current hazards, which plays an important role in producing safer products in the marketplace.

To learn more, visit the UL Solutions HVACR page or view the Roadmap for UL 60335-2-40.


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