Switch cover - for surface-mounted box

Most light switches are recessed into the wall, but sometimes a switch box is surface mounted. In that case the cover, rather than laying flat against the wall, extends into empty space so that its corners catch on every jacket that passes by.

The remedy is a cover plate that does not extend beyond the sides of the box.

Switch boxes vary in size and shape, so the attached SCAD is parameterized to hopefully work for a range of boxes.