Many boxes come with attached brackets of various designs. Several of these brackets are shown in figure 5-12. The D bracket illustration is the simplest one of the group and is simply an extended box side. It is nailed or screwed to the stud. It also has notches to serve as an installation guide. The next bracket is the A bracket. As you can see, it is a straight bracket with a turned over upper edge that fits over the edge (face) of the stud. When nailed from both the front and side, this bracket makes an extremely strong mounting. The A brackets come attached to the boxes at varying distances from their edges to allow for use with different thicknesses of wall material.
The B bracket is made to fasten the box to the face of the stud. It has a couple of spurs that, when driven into the stud, hold the box in place while it is being nailed. The bracket may be attached to the box so it projects slightly above the edge, as shown in the illustration. This bracket prevents the device cover and its holding screws from causing a bulge when sheetrock is used for the wall surface. B brackets on device boxes are located at various depths to coincide with the thickness of the finished wall. Some B brackets are about twice as long as the one shown. These brackets are suitable for mounting on doorway framing studs to place switches and their cover plates beyond the edge of the door trim. This same bracket may be attached to the end of a device box for the horizontal mounting of a switch or receptacle. The J bracket is used the same as any other bracket that is fastened directly to the side of a stud. The holes are slotted to permit the box to be toenailed. The bracket is flush with the edge of the box and has gauging notches for positioning. This bracket has a knockout that allows installation of conduit through the stud into the box. The FA bracket is similar to the D bracket, except the bracket is welded to the side of the box. It also has a positioning spur to assist in holding the box in place while it is being nailed The bracket is offset from the edge of the box one-half inch or five-eighths inch to allow for the wall material thickness. The FH bracket is similar to the FA bracket, except it has two barbed hooks that drive into the face of the stud. The bracket is welded flush on square boxes and offset one-half inch on device boxes. Driving the barbed hooks into the stud face and nailing the side make a very rigid mount. The W bracket is fastened to both the face and side of the stud to provide a rigid mount. Since it stands the box off to the side of the stud, it is used to provide clearance between switches and switch plates and doorway trim, as does the long B bracket.
Box Mounting on Metal Framing
Much modem construction makes use of metal framing members. The ones you are concerned with mostly are the studs and the doorframes. Boxes can be attached with sheet metal screws or machine bolts and nuts. However, special attaching devices are available. A special anchor, as shown in figure 5-13, provides a
Figure 5-12. - Assorted box mounting brackets.Continue Reading