Potter LFH-24W — low frequency 520 Hz audible sounder, off-white faceplate.
NFPA 72 requires 520 Hz low frequency signalling in sleeping rooms, because a low frequency square wave rouses sleeping occupants far more reliably than a conventional high-pitched horn. The LFH produces that square wave in a three-pulse temporal pattern.
- 520 Hz square wave, temporal 3; temporal 4 only with a Potter GTSM module
- Per UL 464 at 10 ft, reverberant: 77.8 dBA normal and 79.8 dBA loud on temporal 3
- Nominal 24 VDC over a 16 to 33 V range, direct current or full wave rectified
- Regulated 24 VDC maximum current 99.4 mA normal, 155.8 mA loud on temporal 3
- Listed to ANSI/UL 464 and CAN/ULC S525; 32 to 120 °F; 18 to 12 AWG terminals
- 6-1/8 × 5-1/2 × 1-5/8 in.; Super-Slide bracket fits 4 in. square and gang boxes
LFH-24R is the same sounder in red, and the LFHS-24 series adds a strobe to this body. Treat the 88.3 dBA figure in Potter architect and engineer wording carefully: the installation manual shows it is the CAN/ULC anechoic rating at 3 m on the loud setting, not the UL 464 number above.
