Electrical Basics:

Connecting A New Branch
To An Existing Electrical Circuit

 
In This Article:

An outlet is pulled out, a new cable is fished into the junction box, and the connections are made.

Related Articles:
Skill Level: 2 (Basic) Time Taken: 15 Minutes

By , Editor

 

This outlet will be the connection point for a new electrical line.

I removed the outlet with a cordless drill-driver.

 

Earlier I had removed this outlet to check how many wires the box contained. 

Because there was only one wire (the line that feeds this outlet) and no other branches, I chose this outlet as a point to begin a new branch.

 

I removed the upper cable clamp. Many metal electrical boxes have these built-in cable clamps. This type uses a single screw to secure one or two cables.

 

With the cable clamp removed, I removed the knock-out. This was quite difficult, as I could not get a screwdriver in the optimum position. But I finally succeeded.

 

Running new electrical cable for a new light fixture. Normally it is easier to run the new cable by starting at the smaller hole and trying to grab it at the larger hole (the opening for the old-work box just three feet higher up the wall).

But in this case, I kept running into some obstruction. It seemed there was a piece of blocking in the wall cavity, standing on edge as to partially block the cavity.

 

So I tried the other way... by inserting the cable into the old work box hole and trying to hit the tiny hole in the metal box.

This method is a long shot, and I figured it would take a while. But the cable end was visible, resting on the top of the box, and all I had to do was direct it into the hole with a screwdriver (working in the gap above the box).

Getting the cable clamp back into the box took forever.

With the new cable extending out of the box by about 6 inches, I stripped back the cable jacket, and connected the two ground wires with this special wire nut.

These green wire nuts are for ground wires and have a hole in the end, so one wire can extend through and connect to the device's ground screw.

 

I stripped back the insulation on the white (neutral) wire and connected it to the empty silver screw on the receptacle. Connecting white wires to electrical outlet.

 

Connecting wires to an outlet (receptacle). I connected the black (hot) wire to the empty gold screw on the receptacle.

About These Terms:

The neutral wire has the same electrical potential as the earth. Theoretically, when everything is working right, you should not get a shock from touching a bare neutral wire (but don't try this!) because at the breaker panel the neutral and ground wires are connected together.

The hot wire is so named because there is high electrical potential (i.e. voltage) between hot and neutral, and also the same potential between hot and ground.

If a neutral wire became open (such as if a wire nut fell off somewhere in the middle of a sequence of connections) then parts of that neutral line could actually be hot, but no devices connected to that part of the circuit would function.  Does this sound baffling? Electricity can be sort of complicated, until you understand the fundamentals.  Read our Science Of Electricity section.

Since this receptacle is in a metal box (and because I know that elsewhere in the circuit there is no ground wire) I wrapped it in electrical tape. This also provides an added layer of protection from shock when the cover plate is removed, such as during painting.

 

I re-installed the outlet and its cover plate.

After the rest of the components were connected, I turned the power on and verified that everything worked.

 

 

Tools Used:

  • Cordless Drill/Driver
  • Flat Blade Screwdriver
  • Needle-nose Pliers
  • Wire Strippers

 

Materials Used:

  • Non-Metallic Cable
  • Wire Nuts
  • Outlet
  • Electrical Tape

 

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Copyright 2000, 2005  HammerZone.com

Written January 30, 2001
Revised January 7, 2005