March 21, 2019
Household Dishwashers – New 11th Edition of UL’s Safety Standard UL 749
By Darrin Conlon – Director of Principal Engineers for Appliances, HVAC/R and Lighting
With the publication of any new edition of a UL safety Standard, users of the Standard typically have a few questions: What are the major changes? How will these changes be implemented? When do they go into effective? It is the intent of this article to answer these important questions.
Major Changes to UL 749 – the Standard for Safety for Household Dishwashers:
The new 11th Edition of UL 749 was published on November 30, 2018. This new edition includes 14 new and revised requirements. The major changes to this Standard are as follows:
1. Dishwasher controls washing test
A Washing Test was added as new clause 15.11 to assess the risk of shock that could result from cleaning around knobs, switches and buttons on the dishwasher's control panel.
2. Resistance to over voltage test
A Resistance to Overvoltage Test was added as new clause 17.5 to address the risks associated with an open neutral condition. This new test is intended to evaluate the robustness of a dishwasher to overvoltage conditions up to 220V.
3. Dishwasher Lampholder Endurance
A Lampholder Endurance Test was added as new Clause 17.6 to assess the risk of electric shock that may occur from exposed live parts as a result of an overheated lampholder. This test is applicable to dishwashers provided with lamps to illuminate the washing compartment
4. Glass used as an enclosure
Requirements for glass parts used as part of a dishwasher’s enclosure have been added to Clauses 19.2.10 – 19.2.14.
5. Heating element requirements
New requirements were added to Clauses 22.5.2 and 22.5.3 to address dishwashers that use in-line heating elements, where the element is not submersed in water, but rather is externally wrapped around the water pipe to heat the water while water flows through the pipe (similar in function as an instantaneous water heater) Sometimes these heating elements are part of the water circulating pump assembly and not in contact with water. Since these types of in-line heating elements are not submersed in water, compliance with the relevant requirements of UL 499 and to the thermal endurance test of UL 1030, are considered to cover the safety attributes needed for use in household dishwashers. Therefore, heating elements (both sheathed and non-sheathed) that are not in contact with the water, can either comply with UL 1030, or comply with UL 499 with the addition of compliance with the UL 1030 Thermal Endurance Test.
6. Appliances shipped from the factory without an outer enclosure installed
Clause 7.2.17 specifies marking requirements for appliances that are shipped from the factory without side or back panels, and Clause 8.1.1 requires a similar instruction. Presently, some dishwashers are shipped without the kick (toe) panel installed to allow access to the field wiring terminals for proper field wiring installation. This also prevents damaging the kick panel when removed for field wiring installation. These two clauses were revised to require the same type of marking and instruction for dishwashers that are shipped with the kick panel omitted.
UL 749 Implementation and Effective Date: Based on the nature of the new and revised requirements with respect to safety, Action is Required by all manufacturers to bring all UL 749 Certified Household Dishwashers into compliance with the requirements specified in the new 11th Edition of UL 749 by the effective date of March 18, 2022.
The Summary of Requirements for the 11th Edition of UL 749 is accessible via the following link:
After clicking on the above link, you can use the “Effective Date Information and Summary of Requirements” section on the left-hand side of the webpage to search by standard number to locate the applicable documents.
If you have questions regarding the above, if you desire training, or if you would like to open a Preliminary Investigation project to learn more about these changes and how they may impact your UL Certified Household Dishwashers, contact Darrin Conlon at (631) 546-2872 or Darrin.Conlon@ul.com.