M3.5 x 35mm Raised Head Countersunk Electrical Screw - 100 Pack

These M3.5 x 35mm raised head countersunk screws are designed for electrical installations, specifically for fixing faceplates to metal back boxes, securing switches to mounting frames, and general electrical accessory assembly. The 35mm length provides sufficient thread engagement for standard 25mm back boxes plus the thickness of a faceplate sub-frame, while the countersunk profile sits flush with or just below the surface of drilled mounting holes.

Supplied in a 100-pack polybag, these screws are intended for electricians and installers working on residential or commercial electrical fitouts where multiple sockets, switches or accessories need fixing. The M3.5 thread diameter is the standard size for UK electrical accessory mounting holes, fitting the pre-drilled apertures in Knightsbridge and most other manufacturers' metal sub-frames and back boxes without tapping.

The nickel plating provides corrosion resistance for installations in bathrooms, kitchens and other moisture-prone areas where plain steel screws would rust over time. The raised head profile gives a larger bearing surface than a standard flat countersunk screw, distributing load across the faceplate material and reducing the risk of pulling through thin plastic or metal covers during tightening.

Product Specification Sheet

What are these screws used for?

They fix electrical accessory faceplates to metal back boxes and sub-frames during socket, switch and dimmer installation. The M3.5 thread diameter is the UK standard for electrical accessory mounting holes.

Will 35mm be long enough for my installation?

A 35mm screw works with a standard 25mm back box plus a typical screwless sub-frame (3-5mm) and faceplate (2-3mm). For deeper installations or surface-mounted boxes, a longer screw may be needed.

Are they compatible with all brands of back box?

Yes. M3.5 is the standard thread size for UK electrical accessory mounting holes across Knightsbridge, MK, BG Electrical and other major brands.

What's the advantage of the raised head over flat countersunk?

The raised head has a larger bearing surface, which spreads the load across the faceplate material and reduces the risk of the screw pulling through during tightening, particularly with thin plastic or metal covers.