1. BS EN 50065-4-4. Signalling on low-voltage electrical installations in the frequency range 3 kHz to 148, 5 kHz. Part 4-4. Low voltage decoupling filter. Impedance filter (23rd April 2021) Authors: British Standards Institution, Record Type: Book Extent: 1 online resource (8 pages) View Content: Available online (eLD content is only available in our Reading Rooms) ↗