2-Way 10-150W Intelligent Dimmer Module - Matt Black

The Knightsbridge GDM150IMB is a 2-way intelligent dimmer module that auto-detects and switches between leading edge and trailing edge dimming modes depending on the connected load. It handles 10-150W incandescent and mains voltage halogen, 10-150W low-voltage halogen with electronic transformers, and 5-150W dimmable LED lamps. The module fits Knightsbridge's 25mm grid wiring system and works with screwless, flat plate, raised edge and metal clad grid faceplates.

Designed for residential and light commercial installations where multiple lamp types might be used over time, the dimmer eliminates the need to specify leading or trailing edge upfront. The rotary knob dims smoothly across the full load range, and the push-on/push-off function allows the dimmer to be operated as a standard switch without touching the knob. The 2-way wiring capability allows the dimmer to be controlled from two locations when paired with a compatible 2-way switch module.

The module is 56.3mm high and 25mm wide, matching the standard Knightsbridge grid pitch, and projects 23mm from the rear of the faceplate. A 35mm minimum back box depth is required for safe installation. The matt black finish on the rotary knob and surround provides a neutral accent that pairs with most grid faceplate finishes. Overload and over-temperature protection prevent damage if the dimmer is accidentally overloaded, and an inrush current limiter handles the high initial current when switching on filament lamps.

Knightsbridge recommend limiting the connected load to 10-12 individual lamps per dimmer to avoid cumulative inrush current issues, even if the total wattage is within the 150W rating. The grid system allows multiple dimmer modules to be fitted side-by-side in a multi-gang faceplate, giving independent control of multiple lighting circuits from a single wall position.

Product Specification Sheet

Product Manual

What's the difference between leading edge and trailing edge dimming?

Leading edge dimmers work by cutting the leading edge of the AC waveform and suit resistive loads like incandescent and mains voltage halogen. Trailing edge dimmers cut the trailing edge and suit capacitive loads like most dimmable LEDs and electronic transformers. This dimmer auto-detects the load type and switches mode accordingly.

Can this dimmer be used with any grid faceplate?

The module fits all Knightsbridge grid systems with 25mm module spacing, including screwless, flat plate, raised edge and metal clad ranges. The faceplate is sold separately and determines the final wall finish.

Why is there a 10-12 lamp limit when the wattage rating is 150W?

Filament lamps draw a high inrush current when first switched on — often 10-15 times their running current for a fraction of a second. With many lamps on one dimmer, the cumulative inrush can exceed the dimmer's inrush current limiter capacity even if the total running wattage is within the 150W rating. Limiting to 10-12 lamps avoids this.

What back box depth is needed?

A 35mm minimum back box depth is required to accommodate the module and wiring behind the grid faceplate. Deeper boxes provide more wiring space and are preferable for multi-gang installations.