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Installing a Switch and Outlet for Power Tools, Troubleshooting an Open Ground and Outlet Heights

June 13, 2010

DIY Electrical Wiring Help Rich asks:
I need a little help with my project. I want to come off my main panel to a switch. From the switch to switched receptacle; controlling a plug in power tool. I have three such switched receptacles. thanks

For a project like this, I recommend installing the switch and receptacle in the same box together. Install a 2 conductor NM cable with a ground wire (14/2 for 15 amp circuits or 12/2 for 20 amp circuits) from the breaker box to your electrical box. Since you are going to control power tools, I recommend installing 20 amp rated, commercial grade devices. These are a little heavier duty and should hold up better than the standard residential grade devices. I highly recommend a GFCI receptacle or a single receptacle over a standard duplex for this application.

To terminate this, start by getting 2, approximately 8 inch long pieces of ground wire and splice them both onto the ground wire you just installed in the 2 conductor NM cable. Connect one of the ground wire tails to the ground screw on the switch and the other to the ground screw on the receptacle. Connect the white wire from the NM cable to the silver colored screw on the receptacle (line side for GFCI). Connect an approximate 6 inch long piece of black wire between one of the brass colored screw on the switch and the brass colored screw on the receptacle (line side for GFCI). Now connect the black wire from the NM cable to the other brass colored screw on the switch. Install the devices and cover plate.

I highly recommend turning off the power to your breaker box before working in here. If there is a breaker in another panel or outside which controls your breaker box, then you shouldn’t have any live power anywhere in the breaker box after turning it off. If there is a main breaker in your box, then the 2 wires which go into that breaker will still be live even after you turn off the breaker. So be very careful. in the breaker box, connect the ground wire to the ground bar. Connect the white wire to the neutral bar and the black wire to the circuit breaker. Put the panel cover on before turning on the breaker. Turn on the power and test. Be sure to label the circuit in the panel.


Lydell Armstrong asks:
My tester reads that I have an open ground even though I know for a fact that all outlets have been grounded. Could you please tell what the problem is?

You probably have a loose connection somewhere and it is probably the neutral wire. Open up all of the boxes that you worked in and look for something wrong.


Alex asks:
How high does the plug need to be off the floor?

I recommend matching the existing heights when adding receptacles in an existing home. If you are wiring a new home a nice trick is to use a hammer to set the height. Place the hammer vertically against the stud. Then place the box against the stud and on top of the hammer. Pinch the box against the stud, remove the hammer and use it to install the box. Typical hammers are approximately 16 inches long. This will put your receptacle boxes at approximately 20 inches to the top of the box.


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