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Three UL 60335-2-34 Standards – Summary Comparison

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July 16, 2018

On November 3, 2017, UL published the Sixth Edition of UL 60335-2-34, the Standard for Safety for Household and Similar Electrical Appliances, Part 2: Particular Requirements for Motor-Compressors. This Standard deals with the safety of refrigerant motor-compressors – the “heart” of a typical refrigeration or air conditioning system. This new edition was created for the purpose of harmonizing U.S. and Canadian motor-compressor requirements with the requirements in IEC 60335-2-34, edition number 5.2.

The requirements in UL 60335-2-34, Sixth Edition became effective on the publication date (November 3, 2017) and motor-compressors are now being certified using requirements in this new edition.

However, the Fourth and Fifth editions of UL 60335-2-34 are still active, and motor-compressors can continue to be evaluated by UL to these editions until March 31, 2021, at which time both of these editions will be withdrawn. For motor-compressors evaluated to the Fourth or Fifth editions of UL 60335-2-34, no industry file review will be mandatory. At the discretion of the manufacturer, motor-compressors evaluated to the Fourth or Fifth Editions of UL 60335-2-34 can remain certified even after these editions are withdrawn on March 31, 2021, provided no changes are made to the construction of the motor-compressors.

There are a number of significant similarities and differences between UL 60335-2-34, Fourth, Fifth and Sixth editions. The following provides a summary comparison between these editions:

Fourth Edition, UL 60335-2-34:

  • U.S. only Standard; does not apply to products certified in Canada or Mexico
  • IEC-based but the numerous deviations eliminate many IEC-based requirements
  • Intended to be used with UL 60335-1, Fourth Edition
  • Not applicable to motor-compressors having (or intended to use) electronically operated or protected controls and/or circuits
  • Covers motor-compressors rated 0 – 600V
  • Retains many of the legacy requirements and tests from the Standard for Hermetic Refrigerant Motor-Compressors, UL 984 (which was withdrawn on December 31, 2017), such as the:
    • Locked-Rotor Current Measurement
    • Off Cycle Crankcase Heating Test
    • Internal Motor-Protector Strength/Calibration Tests
    • Outdoor-use (Rain) Test
    • Motor-Compressor Housing Strength Test (typically based on 5 times design pressure)
    • Gasket Accelerated Aging Test
    • Nonmetallic Enclosure Mold Stress Relief Test
    • Vibration Test
  • Detailed and prescriptive Compatibility Test - Allows insulating material compatibility to be determined by using motorettes, coilettes or individual insulating material parts

 

Fifth Edition, UL 60335-2-34:

  • Trinational Standard; applies within the U.S., Canada and Mexico
  • IEC-based with relatively few deviations, relying primarily on the IEC-based requirements
  • Intended to be used with UL 60335-1, Fifth Edition
  • Applies to motor-compressors having (or intended to use) electronically operated or protected controls and/or circuits
  • Covers motor-compressors rated 0 – 600V
  • Retains only a few of the legacy tests (from UL 984), such as the:
    • Locked-Rotor Current Measurement
    • Gasket Accelerated Aging Test
  • Introduces a new Internal Motor-Protector Strength/Calibration Test
  • Adds Clauses AADV.4 and AADV.5 for motor-compressors using an electronic circuit
  • Clause AADV.5 requires a single test and is conducted at the worst-case condition
  • Nonmetallic requirements in Annex 101.DVDD added to those in Clause 30
  • Overly brief Compatibility Test:
    • No specific test requirement provided but simply indicates that refrigerants, oils and insulating materials are to be compatible
    • Compliance can be demonstrated by an “appropriate certificate” provided by the motor-compressor manufacturer
    • “Appropriate certificate” is not defined by the Standard.

 

Sixth Edition, UL 60335-2-34:

  • Binational Standard; applies within the U.S. and Canada. This edition does not apply to motor-compressors certified in Mexico.
  • More deviations than the Fifth edition, but still relies primarily on the IEC-based requirements
  • Intended to be used with UL 60335-1, Sixth Edition
  • Applies to motor-compressors having (or intended to use) electronically operated or protected controls and/or circuits
  • Covers motor-compressors rated 0 - 15,000 volts
  • Retains a few legacy (UL 984) tests, similar to Fifth Edition
  • Introduces a new Positive Temperature Coefficient Starting Relay (PTCR) Test:
    • Required for all motor-compressors provided with a PTCR
    • Involves increasing the voltage across the PTCR until it fails or ultimate results are obtained
    • 30 sample PTCRs are required for this test.
  • Adds a new Maximum Rated Current (MRC) marking:
    • Required for electronically operated or protected motor-compressors
    • Based on values obtained during Clause AA.4 test
    • Requires determining motor-compressor maximum current at any operating condition including locked-rotor
  • Includes new tests to provide alternate means of complying:
    • Alternate method for using single-phase supply source when conducting Primary Single Phase Failure Test on 3-Phase motor-compressors
    • Optional Pressure (Strength) Test
  • Annex AA.4 similar to AADV.4 in Fifth Edition except includes test for R-744 (CO2)
  • Annex AA.5 differs from AADV.5 in Fifth Edition and requires multiple tests to determine the worst-case condition; includes tests for R-744 (CO2)
  • Nonmetallic requirements in Annex 101.DVC added to those in Clause 30
  • Compatibility Test:
    • Generally aligns with Fourth Edition
    • Allows testing of motorettes, coilettes or the individual insulating material parts
    • Specifies testing of insulating materials in motor-compressors not using any oil (such as those with magnetic bearings)

 

The Sixth Edition is expected to remain active until a future edition of UL 60335-2-34 is published.

For technical inquiries regarding motor compressors, please contact Barry Karnes at Barry.G.Karnes@ul.com.