2 Gang 47mm Galvanised Steel Back Box - Fixed & Adjustable Lugs

The Knightsbridge 2-gang 47mm galvanised steel back box provides the deeper recess needed for modern wiring installations, thicker insulation cables, and accessories with larger terminals or connection blocks. Pressed from 1mm-thick galvanised steel, the box offers corrosion resistance for dry-lining, brick and block wall installations in residential, commercial and industrial settings.

The 47mm depth accommodates dual USB sockets, deep dimmer modules, smart home controls and other accessories that cannot fit in standard 25mm or 35mm boxes. One fixed and one adjustable mounting lug allow the box to be levelled during fitting, even where stud spacing or masonry fixing points are not perfectly aligned. The earth terminal provides a connection point for the earth conductor from the incoming cable and the earth fly-lead from the accessory.

Pre-formed knockouts in 20mm and 25mm sizes sit on all four sides of the box, giving multiple cable entry options depending on the cable run direction. The galvanised finish prevents rust in damp conditions during the build phase, though the box is intended for dry internal use once the wall is plastered or boarded. Compliant with EN 60670, the box meets the dimensional and safety standards required for UK electrical installation work.

Product Specification Sheet

What accessories require a 47mm depth box?

Dual USB sockets, deep dimmer modules, smart home controls, fan isolator switches, shaver sockets and some RCD-protected sockets all benefit from or require the extra depth a 47mm box provides. Standard switches and sockets can also use this box where cable runs are particularly bulky.

Can this box be used in dot-and-dab plasterboard walls?

Yes, provided there is sufficient clearance between the back of the plasterboard and the blockwork or brick substrate. The 47mm depth projects further into the wall cavity than standard 35mm boxes, so check the cavity depth before ordering. The adjustable lug helps compensate for slight variations in board position.

What size knockouts does it have?

The box includes both 20mm and 25mm knockouts on all four sides, giving flexibility for different conduit sizes and cable entry directions. Knockouts are pre-formed and can be removed with a screwdriver or punch during installation.

Is the earth terminal mandatory to use?

The earth terminal provides a safe connection point for the circuit protective conductor (earth wire). While older metal boxes sometimes relied on the mounting screws for earthing continuity, using the dedicated terminal is best practice and required under current wiring regulations for metal enclosures.