Skip to main content
Welcome to the cutting edge of safety science—Learn more about our rebrand.
Switch Language
  • Public Notice

UL Warns of Potential Hazard With LED Lamp and Magnetic Ballast Combinations (Release 18PN-17)

May 15, 2018

NORTHBROOK, Ill., May 15, 2018 — UL, a global safety science organization, is warning building owners, installers and consumers that installing double-ended direct replacement LED lamps in energized luminaires powered by magnetic 40 watt ballasts may pose a shock hazard.

Recent UL testing confirms that luminaires with magnetic ballasts intended for F40T12 fluorescent lamps may pose a risk of electric shock during installation of LED lamps intended for direct substitution of a fluorescent lamp while the circuit is energized. To date, UL has not received any reports of persons receiving an electric shock while replacing lamps on these older magnetic 40 watt ballasts.

Magnetic ballasts intended for F40T12 fluorescent lamps have not been available in the marketplace for many years. However, given their prior widespread use, these magnetic ballasts may still be in service in some older installations.  To enhance safety, UL always recommends that all luminaires be deenergized during lamp installation or replacement.

About UL

UL fosters safe living and working conditions for people everywhere through the application of science to solve safety, security and sustainability challenges. The UL Mark engenders trust enabling the safe adoption of innovative new products and technologies. Everyone at UL shares a passion to make the world a safer place. We test, inspect, audit, certify, validate, verify, advise and train and we support these efforts with software solutions for safety and sustainability. To learn more about us, visit