How Recent Changes in UL Standards Affect Fans

by Dave Mayer |

You may have been familiar with fans meeting UL Listing criteria that aligned under three UL Standards: Power Ventilators (UL 705), Power Ventilators for Smoke Control, and Power Ventilators for Restaurant Exhaust (UL 762). As of June 2021, UL made changes to these standards. Here’s a breakdown of what these standards covered and the recent changes.


UL 705 Power Ventilators is intended to assure the buyer of the safety of electrical components and connections within power ventilators (roof and wall-mounted) and duct fans (straight-through type). This standard is limited to fans for commercial or industrial use for connection to permanently installed wiring systems that meet NFPA 70 and the National Electrical Code (NEC). This listing does not include fans used where heat, grease, corrosive or flammable atmospheres, where dust, material, or refuse are present.


UL 762 Power Ventilators for Restaurant Exhaust is concerned with the safety of roof or wall-mounted power ventilators used with restaurant exhaust appliances, where heat and grease are typically encountered in the airstream. These fans must also be installed in accordance with NFPA 96.


Power Ventilators for Smoke Control is concerned with the removal of smoke-laden, and potentially high-temperature vapors in the event of an emergency.


What’s changed?

The following changes have been made to UL 705 and UL 762:

  • UL Standard 762 "power ventilators for restaurant exhaust appliances" has been merged into UL Standard 705 as "Supplement SC".
  • UL requirements for "power ventilators for smoke control systems" have been merged into UL Standard 705 as "Supplement SD".

Please note:

  • UL793 "Standard for automatically operated roof vents for smoke and heat" has not changed and is still an active standard.
  • No changes have been made to the product requirements or testing that is called out in these standards.


What should engineers and contractors do in light of these changes?

Engineers should no longer refer to "UL762" when specifying restaurant/grease exhaust fans. Instead, specify "UL705 - supplement SC - restaurant exhaust". For smoke control fans, use “UL705 - supplement SD - smoke control”.

Contractors and code officials—be aware of these changes so you are not surprised if you do not see "UL 762" on product documentation or submittals. Product labeling does not contain the UL standard number so you shouldn't notice a difference on the product itself.


What Greenheck is doing as a result of these changes?

We are updating applicable products in our Computer Aided Product Selection (CAPS®) program, as well as product submittals, product catalogs, and our website to reflect the changes.  In many cases, we will refer to both the new and old UL standards to help with the transition.

If you have any questions regarding these changes, contact your local Greenheck representative.

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Dave Mayer
Dave Mayer
Dave Mayer
Dave Mayer is the product manager of Greenheck’s Power Roof Ventilator (PRV) and Roof Curbs business unit. He has been with Greenheck for 18 years and holds a bachelor’s degree in mechanical engineering from the University of Wisconsin.
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