What size back box do I need for a Shelly?

Shelly’s are small, and as a result, it’s common for Shelly 1L’s and Shelly Dimmer 2’s to be installed in a back box or behind the ceiling rose.

There are three standard depths of back boxes in the UK: 25mm, 35mm, and 47mm.

In either case, most Shelly’s are typically around 39mm x 36mm x 17mm in dimension, which means they’ll fit comfortably in a 35mm or 47mm deep back box.

If you have a particularly busy back box with many wires and connectors, you may benefit from first replacing it with a 47mm back box to give yourself a bit more room to work.

Can I use a metal or plasterboard?

Galvanised steel and plasterboard back boxes are both sufficient for installing a Shelly. It is equally as easy to install a Shelly in a metal back box as it is to install one in a plasterboard back box.

Where can I buy them?

We sell both 35mm and 47mm back boxes for brick (steel), Dry Lining (dry wall/plasterboard) and surface mounting:

• Single Gang Galvanised Steel Knockout Box (Back Box) 35mm
• Single Gang Galvanised Steel Knockout Box (Back Box) 47mm
• Single Gang Dry Lining Knockout Box (Back Box) 35mm
• Single Gang Dry Lining Knockout Box (Back Box) 47mm
• Single Gang Surface Patrress Box (Back Box) 35mm
• Single Gang Surface Patrress Box (Back Box) 47mm