Wheelock Exceder LED3 520 Hz Low Frequency Sounder Strobes


Industry-first to meet both NFPA 72 and NFPA 720 new code requirements for sleeping rooms

With the Exceder LED 520 Hz low frequency sounder strobes, organizations can now meet both sleeping room codes – NFPA 72 and NFPA 720 - with one device, which features two different sound patterns, T3 for fire detection and T4 for CO.  The low frequency sounder strobes can replace a facility’s existing appliances, utilizing the same single pair of wires that are currently installed, offering a simple retrofit to meet new codes for sleeping rooms.

The Exceder LED low frequency sounder line features multiple 520 Hz modes of operation: T3, T4, Continuous, and T3/T4. When the device is set to T3/T4, the appliance can switch from T3 to T4 based upon the condition sensed by the fire alarm control panel.

Like the entire Wheelock Exceder LED product line, the models feature one of the industry’s smallest footprints and a sleek, modern, low-profile design. The low-frequency sounder strobes will utilize a light emitting diode as the light source, resulting in best in- class efficiency that enables material and system cost savings, allowing for a greater number of appliances on the notification appliance circuit and fewer power supplies. Low and high candela strobe models meet the 20 millisecond light pulse duration requirements of the 2016 edition of NFPA 72.  LFHSK3 strobe models include a 110 candela setting, and LFHSH3 strobe models include a 177 candela setting.

UL Compatibility Letter for Exceder LED3

520 Hz sounder NFPA code requirements

Customer Success Story

Finish Color Red or White
Mounting Wall
Lettering ALERT, FIRE, CO, No Lettering
4 Settings in 1 Device T3 (fire), T4 (CO), Continuous (coded), T3/T4
Strobe Candela LFHSK3 strobe models: 110 cd; LFHSH3 strobe models: 177 cd
Backbox Mounting Options LFTP trim plate for single-gang backbox included in all LFHSK models; LED speaker backboxes and 4” square backboxes
Approvals UL, ULC, CSFM, RoHS, NFPA 72 20 ms flash duration requirements


  • Meets dual low frequency sounder codes for sleeping rooms in a single device
    • NFPA 72 for fire alarm
    • NFPA 720 for CO alarm
  • Low-Profile Design and one of the smallest footprints with sleek, modern aesthetics
  • Energy Efficient and Environmentally Friendly
    • Industry’s first LED strobes, providing the low current draw
    • Fewer power supplies required, smaller wire gage, reduced wire runs
  • Convenient Mounting Options - LFTP trim plate for single-gang backbox included in all LFHSK models; LED speaker backboxes and 4” square backboxes
  • Easy-to-Install with finger slide switches with no tools needed for setting changes 
  • Fast installation with IN/OUT screw terminals using #12 to #18 AWG wires