UL 507 Standard for Safety on Electric Fans
A new update to “UL 507 Standard for Safety, Electric Fans”, went into effect on November 27, 2024 and must be implemented on these products as of that date. This update adds requirements for Listed electric fans that are used in “Unattended Areas”. Because radon fans are mounted in attics, garages and outdoors these changes must be implemented on all such Listed fans with AC induction motors.
UL Standards are developed by a committee which includes UL, industry, government, consumer and other groups much like the AARST/ANSI standards. The UL standard is used by UL, ETL, CSA and other Nationally Recognized Testing Laboratories to certify products. The UL standard covers all types of fans (not just radon fans) and many aspects of product safety including mechanical integrity, electric shock hazards, flammability and suitability for use.
Radon fans have an outstanding safety record with millions and millions of fans installed over the past 40 years. But because a fan is a mechanical device it will eventually reach the end of its service life, and the new requirements were added to ensure that no hazards are created when the fans eventually die.
The standard changes were implemented after the Consumer Product Safety Commission was called in to investigate a series of fires caused by bathroom ceiling fans on a US Army base. The cause of the fires in these low-cost bath fans was traced to shorts in the motor winding on stalled motors. This led to the eventual change for all fan types in “Unattended Areas”.
Motors generally have a primary thermal protector that shuts the motor off if it overheats. Key to the UL507 change is the addition of either a secondary thermal or a current fuse, along with an extensive suite of testing. The fuse will ensure that motors will not spark if the windings short out. Radon fan motors are typically totally enclosed, which means they have a metal case surrounding them, so sparking is generally not a concern. Nonetheless, the new UL507 requires an additional fuse.
A minimum of 25 motors must be submitted to the Testing Lab for certification to the new standard version. 10 motors are tested as submitted to determine if the primary and secondary thermal protection are functional. 15 motors then go into an oven at approximately 250 degrees Fahrenheit for 12 weeks. This long thermal soak is to simulate years of use in the field. After the oven the 15 motors are again tested to ensure the primary and secondary thermal protections are still functional. Only then will the manufacturer get the Authorization To Mark (ATM), which means the product meets the new standard version.
Safety is a primary concern for the radon industry. Radon systems provide safety to the families that live in the home. This new safety standard revision serves to increase the overall safety and professionalism of the radon mitigation industry and installer. Ask your fan manufacturer if this new safety standard is part of the products you buy and look for the ETL or UL mark on the label with a statement that the fan was tested to the UL507 standard.
Dave Kapturowski
Vice President & Co-Founder
Spruce Environmental Technologies, Inc.
