1 Gang 2-Way 10-200W Intelligent Dimmer - Black Nickel Screwless

The Knightsbridge SF2191BN is a 1-gang 2-way intelligent dimmer rated for 10-200W incandescent or halogen loads, or 5-150W LED loads. The dimmer switches between trailing-edge mode (default, optimised for LED) and leading-edge mode (for traditional incandescent and halogen) via a control sequence on the rotary knob, allowing it to adapt to different lamp technologies without rewiring.

Designed for living rooms, bedrooms, dining rooms and home offices where dimming control is needed on a single lighting circuit, the dimmer fits a standard 25mm minimum back box depth and uses a screwless black nickel faceplate that clips onto a separate metal sub-frame. The rotary control knob provides push on/off functionality and continuous rotary dimming from minimum to maximum brightness. A quick trim function accessed via the knob allows the minimum brightness level to be calibrated to the specific lamp being controlled, preventing flicker at low settings.

The black nickel finish is a dark gunmetal tone that sits between polished chrome and matt black, pairing well with contemporary, industrial and monochrome interiors. The screwless design removes visible fixings from the wall once installed, giving a cleaner finish than traditional screw-fixed plates. The dimmer includes overload and overheat protection that cuts power if the load exceeds the rated capacity or if internal temperature rises beyond safe operating limits. The 87.5mm square faceplate and 4.3mm projection from the wall give a low-profile presence that suits both modern flush installations and traditional rooms where a discreet dimmer is preferred.

For best performance, use the dimmer with lamps of the same brand, wattage and technology on a single circuit — mixing LED and halogen, or different LED brands, can cause inconsistent dimming behaviour or flicker. The 2-way wiring allows the dimmer to be paired with a second switch elsewhere in the room (e.g. opposite ends of a hallway, top and bottom of stairs), with the dimming control only available at the dimmer location.

Product Specification Sheet

What's the difference between trailing-edge and leading-edge modes?

Trailing-edge mode (the default) is optimised for LED and low-voltage halogen lamps with electronic transformers. Leading-edge mode suits traditional incandescent bulbs and halogen lamps with wire-wound transformers. The dimmer ships pre-set to trailing-edge and can be switched to leading-edge by holding the rotary knob in a specific position during power-up — see the datasheet for the exact control sequence.

Can I use this dimmer with mixed lamp types on the same circuit?

No. For reliable performance, all lamps on the circuit should be the same brand, wattage and technology. Mixing LED with halogen, or different LED brands, can cause flickering, inconsistent dimming or early lamp failure.

What back box depth is required?

A 25mm minimum back box depth is needed. The dimmer has a 21.3mm recessed depth behind the faceplate, and the screwless cover adds 4.3mm of projection from the wall once installed.

Is the screwless plate removable for redecorating?

Yes. The black nickel cover plate clips onto a separate metal sub-frame fixed to the back box. The cover can be removed for painting around the dimmer and re-clipped without re-wiring.