Grabbing Power


When planning new electrical service, begin by deciding where you can tap into power. If you are adding a couple of receptacles or lights, it is usually easiest to grab power from a nearby receptacle or junction box. First, however, make sure the new service doesn't overload the circuit.

If nearby boxes are on circuits that do not have enough available wattage for the new service, try a box farther away. If no circuit is usable or if the new service needs its own circuit, run cable all the way to the service panel and connect to a new circuit breaker.

If you need to, run cable through walls and ceilings to get at power.


About 2 hours to connect new cable to an existing receptacle or junction box (not including cutting a pathway for the cable and patching walls)

Voltage tester, drill, pry bar, saw, close-work hacksaw or reciprocating saw, hammer, screwdriver, strippers, long-nose pliers, lineman's pliers

Stripping wire and connecting wire to terminals, running cable through walls, prying and cutting nails

Spread a drop cloth or towel on the floor. Run cable to the box from which you grab power.

New cable, wire nuts, electrician's tape, cable clamps, remodel box

Step 1

To grab power from a receptacle, make a load list to verify that there is room on the circuit for new service. Shut off power to the circuit and test that power is not present. Disconnect the receptacle.

Step 2

If the box is inside a wall, cut a hole into the wall to get at the box or pull the box out. Pry with a flat pry bar, then remove the nails or cut through them with a close-work hacksaw or reciprocating saw.

Step 3

Pull out the box carefully -- the cable may be stapled to a stud. Disconnect the cable(s) from the old box. Choose a remodel box to fit the hole. Clamp the old and new cables to the remodel box.

Step 4

Push the remodel box back into place and clamp it to the wall.

Step 5

If the new receptacle is at the end of the run (with only one cable entering the box), simply connect the new wires to the proper terminals and connect the grounds.

Grabbing Power from a Junction

To grab power from a junction box, shut off power, remove wire nuts, and splice the new wires. You may need to cover the resulting splices with larger wire nuts.

Grabbing Power from a Switch

You can grab power from a switch box only if power enters the box (rather than going to the fixture) and two cables are present. Connect with pigtails as shown.

Grabbing Power from a Mid-Run Receptacle

If two cables enter the box, the receptacle is in the middle of a run. Splice the wires and connect to terminals with pigtails as shown. The purpose of pigtails is to avoid multiple connections to one terminal screw where they could easily short or come loose. Make pigtails by removing the sheathing from about 8 inches of NM cable. Strip about 3/4 inch for each end of the black and white wires and attach them as shown.

Comments (2)
dpage110 wrote:

This is useless? I mean it tells me what I already know. How about some details?

12/5/2010 10:35:19 PM Report Abuse
lmn4562003 wrote:

There is a single light fixture above mirror. I want to change to two separate fixtures, side by side. Can I grab power from existing light fixture box to add a second light fixture box?

10/25/2009 03:41:26 PM Report Abuse
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