Electrical & Electric

Installing a Surface or Flush Mounted Electrical Box 

Installing Electrical Boxes

Introduction:

There are basically two types of electrical boxes available; metal electrical boxes and plastic electrical boxes. Each of these boxes can be mounted in a different way. Installing a surface or flush mounted electrical box is an easy DIY project. A flush mounted box is attached directly to the wall surfaces. They are generally used in garages or basements.

The flush mounted box is the most common method for installing electrical boxes but they can also be mounted to the wall surface. Most of these boxes are sized for a single, double or more switches, electrical plugs, or a combination of switches and plugs.

Surface mounted boxes:

Surface mount electrical boxes are used to mount a surface switch or plug. They are usually used in garages or basements. The box is mounted flat on the wall surface although some are mounted into a small cavity within the wall.

Mounting on masonry walls:

• For mounting on a masonry surface hold the box on the wall at the position where you would want it and ensure that it is horizontal using a spirit level. When it is horizontally level, mark the attachment holes and remove the box. Drill where you marked the fixing holes to attach the box.

• Determine where the electrical wiring will enter the box and use pliers to break out the entryway for the wire. Pass the wire through the hole and align the mounting box up to the mounting holes you have drilled. Use countersunk screws to fix the mounting box to the wall. Before fully tightening the screws use the spirit level to level the mounting box.

Mounting on sheetrock walls:

• Attaching a surface mount electrical box on sheetrock or plaster walls can be done in a similar way to masonry.  

• Place the mounting box on the wall and align it so that the fixing screws go into the wooden frame or 2x4 behind the wall. Check that it is possible to feed in the electrical wire from behind the box.

• Mount the box and feed the electrical wiring into the box.

Flush mounted on masonry walls:

• On masonry walls place the metal mounting box against the wall at the desired location and draw around it with a pencil. Mark a path for attaching the electrical wire.

• Remove the material from within the marked area by first scoring the pencil line using a masonry chisel and hammer to cut the hole.

• Once the material is removed insure the box fits into the wall and then mark and drill holes to attach the mounting box to the brick behind. Pull through the length of electrical wiring required and attach the mounting box in the hole.

• Finish by plastering around the box and the cable channel as necessary.

Flush mounted on sheetrock walls:

• Once you have decided where the box is going to be located, draw around the mounting box on the wall ensuring that it is level using a spirit level. Cut the hole in the wall using a sharp knife. Feed the cable through the best wire entry hole in the box.

• Fit a grommet to the wire entry hole and fit two lugs to the mounting box. Then pass the cable through the grommet and slide the box into the wall so that both of the lugs are behind the wall. The box should now sit behind the wall and flush to the surface. Attach the electrical outlet or switch you want for the location.  

That is all there is to mounting a surface or flush mounted electrical boxes.

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