Back Boxes & Accessories

Which back box do you need for your wall?

The wall decides the type of box. In solid brick or block, a flush box sits in a chased recess so the plate finishes level with the plaster. Plasterboard and stud walls usually take a dry-lining box, which grips the board from behind with lugs. Where cable runs on the surface, or chasing in is not practical, a surface pattress box mounts on the wall and the plate fixes to its front.

Not sure which you have? A hollow knock usually means plasterboard on studs, while a dull, solid knock means brick or block. Many of the back boxes we stock suit commercial fit-outs, and we also stock a few related electrical accessories.

Single back box or double back box?

Match the box to the plate. A single back box takes a single gang switch or socket, while a double back box takes a double gang plate, such as a twin socket or a double light switch. A single plate will not cover a double box, and a double plate will not fix to a single box. Triple and larger multi-gang boxes take wider plates, often grid plates carrying several switch modules.

Many of our back boxes are single gang and many are double gang. We also stock some triple gang boxes and a few larger multi-gang sizes, and some are modular.

How deep should a back box be?

Depth matters as much as width. A plain switch needs little room behind the plate, but dimmer switches, USB sockets and fused spurs have bulkier bodies and need a deeper box. A box that is too shallow squashes the cables and stops the plate sitting flat against the wall, so check how much depth your switch or socket needs before you order.

In overall size, most of the boxes we stock are small, many are medium and a few are large. Measure the recess, or the wall space for a surface box, and compare it with the box dimensions before you choose.

Choosing a light switch back box

Almost all of the back boxes we stock are made for switches and sockets, so finding a light switch back box comes down to gang size, depth and the shape of the plate. Line up the box's fixing lugs with the screw holes in your plate. On a surface box the edges show, so match a rounded or square plate to the shape of the box.

If you want a light switch with a back box, read the listing to see what comes with the switch. If it arrives without a box, pick a back box that matches its gang size and the depth it needs.

Choosing a back box material and finish

Many of the boxes we stock are metal, some are steel and a few are stainless steel. Many are resin or polycarbonate, some are ABS, and we also stock a concrete back box. Some have an industrial look. A metal box should be earthed, which a qualified electrician will see to when fitting it.

Many of our back boxes are white and many are silver, with some in black, chrome or grey and a red back box too. A flush box sits hidden behind the plate, so its finish matters little, but a surface box is on show, so match its finish to your switch or socket.

Fitting back boxes: what to check first

Mains wiring is a job for a qualified electrician. In England and Wales, electrical work in the home falls under Part P of the Building Regulations, and some jobs must be notified to building control, so ask your electrician to certify the work. Before cutting a recess, check the wall for hidden pipes and cables.

Most of our boxes carry an IP20 rating, which suits dry indoor spaces only. Near a bath or shower, the box and accessory need a higher IP rating for the bathroom zone, so check with your electrician before fitting anything near water.