M3.5 x 50mm Flat Head Countersunk Electrical Screw - Brass (100 Pack)

These M3.5 x 50mm flat head countersunk screws are designed for electrical installations where a flush finish is required. The brass construction provides corrosion resistance and a warm metallic finish that matches brass faceplates and accessories. Each screw features a countersunk head that sits flush with or below the surface when driven, making them suitable for use with screwless cover plates and flat plate electrical accessories.

Supplied in a 100-pack for professional installations, trade jobs, and high-volume residential projects, the 50mm length provides enough thread engagement for standard 25mm back boxes with the cover plate sub-frame in place. The M3.5 diameter is the standard thread size for UK electrical accessories including Knightsbridge screwless sockets, switched faceplates, and dimmer modules. The brass finish coordinates with polished brass, antique brass, and brushed brass electrical ranges.

The countersunk head profile allows the screw to sit below the surface of the fixing hole, ensuring the screwless cover plate clips cleanly onto the sub-frame without interference. Unlike steel or zinc-plated screws, the solid brass construction won't corrode in damp environments and provides a better colour match when visible through precision-machined apertures on high-end electrical accessories. Each screw is threaded along the full 50mm length for maximum holding power in metal and plastic back boxes.

Product Specification Sheet

What are these screws used for?

M3.5 x 50mm screws are the standard fixings for UK electrical accessories including screwless sockets, switched faceplates, dimmers and cooker control units. The countersunk head sits flush with the sub-frame fixing holes, allowing screwless cover plates to clip on cleanly.

Will these fit standard UK back boxes?

Yes. The 50mm length provides enough thread engagement for a standard 25mm back box with the screwless sub-frame fitted. For deeper back boxes or surface-mounted installations, shorter screws may be more appropriate.

Why brass instead of steel screws?

Brass screws provide better corrosion resistance in damp environments and colour-match brass electrical accessories. They're also softer than steel, reducing the risk of cross-threading or damaging plastic back boxes during installation.

How many screws are needed per socket or switch?

Most single or double gang sockets and switches use two screws to fix the sub-frame to the back box. A 100-pack is sufficient for approximately 50 electrical accessories.