Adjustable-depth ring assembly and method of installation

An adjustable-depth ring assembly for mounting an electrical device in an electrical box that is accessible through a wall opening in a wall member disposed forward of the electrical box, comprising

• a box cover plate having a central opening, said box cover plate being adapted to be mounted on a front side of the electrical box and rearward of the wall member with the central opening in registration with a recess in the electrical box and said wall opening,
• an extension ring received in the central opening of the box cover plate, said extension ring having top, bottom and side walls extending rearward from a front of the ring and defining a cavity for receiving said electrical device, and at least one opening in the ring at the front of the ring for receiving a fastener to fasten said electrical device to the ring,
• fastener openings in the box cover plate for receiving fasteners to fasten the box cover plate to the electrical box,
• fastener openings in the extension ring for receiving fasteners to fasten the electrical device to the extension ring,
• said extension ring being movable relative to the cover plate along an axis extending in front-to-back direction such that an axial distance between the front of the extension ring and the box cover plate can be adjusted to accommodate wall members of different thicknesses,
• spring detents on one of the box cover plate and extension ring for engaging the other of the box cover plate and extension ring, and
• an abutment device on the extension ring movable from a non-abutting position to an abutting position projecting outward beyond a perimeter of the extension ring for abutting a front surface of said wall member when the extension ring is moved to an installed position.