Renovation 4th Edition

by Michael Litchfield

  either side to engage internal clamps that grip

  tripping of the GFCI receptacle.

  the wire, thus ensuring a solid connection. Avoid

  receptacles that lack this feature. They aren’t reli-

  able. (Back-wired switches, on the other hand,

  rarely fail.)

  If the GFCI is going to protect users at a

  single outlet, attach incoming wires only to LINE

  screw terminals. The yellow tape across one set

  of screws indicates that they are load terminals.

  If you are hooking up the device to protect only

  a single point of use, leave the tape in place and

  connect wires only to the screw terminals

  marked “line.” After attaching the ground pigtail,

  screw down the silver screw to secure the

  neutral pigtail.

  Connect the hot pigtail to the brass screw last,

  then push the device into the box carefully, hand

  screw it to the box, and install a cover plate.

  Quality GfCI receptacles can be

  By using pigtails, you wire a GfCI

  Feeding the circuit through a GFCI receptacle.

  reliably wired by inserting stripped

  receptacle to protect only itself and

  If you want to use a single GFCI receptacle to

  wire ends into terminal holes in the

  not outlets downstream.

  protect downstream outlets, attach the outgoing

  back where screws tighten pressure

  plates to hold the wires, or by

  wires to the “load” terminals of the GFCI recepta-

  attaching wires to screw terminals on

  cle. That is, connect incoming and outgoing cable

  the side. note the “lOAD” and “lInE”

  wires directly to the device rather than using pig-

  descriptors; they are important.

  tails. Again, it’s important to connect incoming

  wires to the terminals marked “line” and outgo-

  ing wires to terminals marked “load.”

  Wiring a split-tab receptacle. Standard duplex

  A GfCI receptacle wired to protect a

  receptacles have a small metal tab between the

  single outlet has just three wires

  brass screw terminals. The tab conducts power to

  attached: a ground wire to the

  both terminals, even if you connect a hot wire to

  ground screw and a neutral wire and

  just one terminal. However, if you break off and

  a hot wire attaching to terminals

  remove the tab, you isolate the two terminals and

  marked “lInE.”

  302 Chapter 11

  gfCi receptacle, Multiple-location

  S a f e t y a l e r t

  Protection

  From power

  zzzzzz

  if you install three-prong

  source

  receptacles on an ungrounded

  circuit, the neC requires the new

  receptacles be gfCi-protected

  and that you label affected

  receptacles “no equipment

  ground.”

  Spliced

  ground

  wires

  A GfCI receptacle wired to protect

  outlets downstream does not use

  pigtails for hot and neutral wires.

  Incoming wires from the power

  source attach to terminals marked

  To devices

  “lInE”; outgoing wires attach to

  downstream

  LINE

  T

  terminals marked “lOAD.”

  NEUTRAL

  HO

  WIrInG A SPlIT­TAB rECEPTAClE

  Neutral

  LOAD

  NEUTRAL

  THO

  *Devices

  include

  Hot

  receptacles,

  switches, and

  light fixtures.

  A GFCI receptacle can protect devices* downstream

  if wired as shown. Attach wires from the power source

  to terminals marked "line." Attach wires continuing

  downstream to terminals marked "load." As with any

  receptacle, attach hot wires to brass screws, white wires

  to silver screws, and a grounding pigtail to the ground

  screw. Note: Here only ground wires are spliced; hot and

  neutral wires attach directly to screw terminals.

  1. To convert a standard duplex

  2. Connect the ground wire to the

  receptacle into two single

  green grounding screw, then the

  create, in effect, two single receptacles—each of

  receptacles, start by twisting off the

  neutral to one of the silver screw

  which requires a hot lead wire to supply power.

  small metal tab between the two

  terminals.

  brass screw terminals.

  This technique, known as split-tab wiring, is

  often used to provide separate circuits from a

  single outlet, a configuration commonly used

  when connecting a disposal and a dishwasher.

  The disposal receptacle is almost always con-

  trolled by a switch, which allows you to turn off

  the disposal at another location. To supply two

  hot leads to a split-tab receptacle, electricians

  usually run a 12/3 or 14/3 cable.

  To create a split-tab receptacle, use needle-

  nose pliers to twist off the small metal tab

  between the brass screws. Next, connect the bare

  ground wire to the green grounding screw on the

  device and connect the white neutral wire to a

  silver screw. If you keep a slight tension on the

  wires as you tighten each screw, they’ll be less

  likely to slip off.

  3. Connect the hot wires last.

  4. A correctly wired split­tab

  Flip the receptacle over to expose the brass

  removing the tab creates, in effect,

  receptacle. Typically, one wire is

  screws on the other side, and connect a hot lead

  two receptacles, so each needs a

  controlled by a switch.

  to each brass screw. If you’re running 12/3 or

  separate hot wire. It’s common to use

  14/3 cable, one hot wire will typically be red and

  a 12/3 or 14/3 cable for split­tab

  the other black. Finally, push the receptacle into

  circuits. Typically, one hot wire of the

  cable will be black, the other red.

  electrical Wiring

  303

  the box, install the mounting screws, and apply

  insert wires into holes on the back of the device.

  the cover plate.

  Here, back-wiring is acceptable because you

  Although this 15-amp split-tab receptacle

  must tighten screws on either side to engage

  is fed with 12/3 cable (rated for 20 amps), there’s

  internal clamps that grip the wire and ensure a

  no danger of the load exceeding the rating of

  solid connection.

  the receptacle. Because of the configuration

  of the slots, the receptacle can receive only a

  Wiring Switches

  15-amp plug.

  Because switches interrupt only hot wires, you’d

  think they’d all be easy to wire. As you can see

  baCksTab or Push-in deviCes

  from the wiring schematics on pp. 314–315, how-

  A backstab switch. After stripping the Cheap backstab receptacles have holes in the

  ever, switch wiring can be q
uite complex, espe-

  wire end, insert it into a back port/

  back, into which you push stripped wire ends,

  cially three-way and four-way switches and

  hole until the wire bottoms, then pull which are grabbed by strips of spring metal.

  switches with electronic components. So follow

  gently to make sure that the device’s

  They’re quicker to wire than screw terminals, but the manufacturer’s instructions carefully. Simple

  internal clamp has gripped the wire

  the receptacle’s internal spring clamps can weak-

  securely.

  switches have a top and bottom, so wire the

  en, leading to loose wires, flickering lights, and

  switch correctly.

  arcing. Moreover, each time you insert and

  Before connecting wires to a switch (or dis-

  remove plugs, the receptacles move slightly,

  connecting wires, if you’re replacing one) use a

  which increases the likelihood of clamp failure.

  voltage tester to make sure that the wires aren’t

  Manufacturers have stopped making back-wired

  energized. Test with the switch both on and

  20-amp receptacles. Backstab switches, on the

  off to be sure.

  other hand, rarely fail.

  Wiring a single-pole switch. The most com-

  Also, high-quality devices such as the GFCI

  monly installed switch, a single-pole, is straight-

  receptacle shown in the photo on p. 302 allow

  forward to wire. Spliced together during the

  you to loop wires around its screw terminals or

  rough-in stage, the neutral wires stay tucked in

  the outlet box. Pull ground and hot-wire groups

  out of the roughed-in box. Use the hole in the

  handle of your wire strippers or use needle-nose

  pliers to loop the conductor ends so they can be

  wrapped around the screw terminals.

  light fixture at end of

  Cable run

  zzzzzz

  1. When wiring switches, leave

  2. next, attach the hot wires to terminals. One wire is

  To fixture

  neutral wires tucked in the box.

  considered the hot (from the power source), whereas the

  Switches interrupt the current

  other is the switch leg (power going out to the fixture).

  flowing through hot wires only.

  With a single­pole switch, it doesn’t matter which hot

  Attach the ground wire first.

  wire you attach to which screw.

  Ground

  Neutral

  Incoming power

  Hot

  3. Wires are ready to be tucked into 4. Straighten switches in the box, and tighten the screws

  the box.

  carefully so you don’t strip the box’s threads. Using a drilldriver will speed the task.

  304 Chapter 11

  Wiring a “switch loop”:

  WIrInG switches

  the historical Method

  Before connecting or disconnecting wires to a

  zzzzzz

  switch, use a non-contact tester to make sure

  In the “old school” way of wiring a switch loop,

  that the power to the switch outlet is off.

  a single length of two-wire cable serves as a

  test with the switch flipped both on and off

  Ground

  switch leg. The white wire in the cable is taped

  to be sure.

  black to show that it is being used as a hot wire.

  Because switches interrupt only hot wires,

  It was a good solution because it conserved

  you’d think they’d all be easy to wire. as you will

  copper and was quick to wire, but it has been

  superseded by the method shown below.

  see, however, switch wiring can also be quite

  complex, especially three-way and four-way

  switches and switches with electronic compo-

  nents. Follow the manufacturer’s instructions

  Hot white wire

  carefully.

  taped black

  First, attach the ground wire to the green

  A single length of two-wire cable

  grounding screw on the switch. Orient the wire

  serves as a switch loop

  loop in a clockwise direction—the same direction

  the screw tightens. When the loop faces the

  other way, it can be dislodged as the screw head

  is tightened.

  Next, connect the hot wires to the switch ter-

  minals, again orienting wire loops clockwise.

  One black wire is hot (power coming in), and the

  other is the s witch leg (power going out to the fix-

  ture). With a single-pole switch, however, it

  doesn’t matter which wire you attach to which

  screw. Generally, pros attach the hot wire last, as

  they attach the hot wire on a receptacle last.

  Once the ground and hot wires are connect-

  ed, the switch can be tucked into the box. Always When an outlet or fixture box is closer to the power

  As is customary, connect the ground

  push the device into the box by hand until it’s

  source than to the switch box, it’s common to run a single

  wire first, then connect the hot wire

  length of 12/2 or 14/2 cable as a switch loop. Because the

  and the switch­leg wire to screw

  flush to the wall. Don’t use the screws to draw a

  white wire in the cable functions as a switch leg, tape it

  terminals. When all connections are

  device to a box because the device may not lie

  black to show that it functions as a hot wire.

  tight, tuck the wires into the box and

  flat, and it’s easy to strip the screw holes in a

  screw the switch to the box.

  plastic box. Using a cordless drill/driver is a lot

  faster than using a screwdriver, but use a light

  Wiring a “switch loop”:

  trigger finger on the torque clutch of the driver

  the Modern Method

  The 2011 NEC requires that

  there be a neutral in every

  to avoid striping the screw head or snapping off

  zzzzzz

  switch box because some

  the screw.

  electronic timer switches and

  Ground

  a single-pole switch with a “switch loop.”

  other energy-saving controls

  This section shows two ways of wiring a switch

  Neutral available need a neutral. Thus, if you

  for electronic

  when an outlet or fixture box is closer to the

  switch

  want to use a switch-loop

  power source than to the switch box, commonly

  approach, you must use

  called a switch loop. The first way to wire a

  three-conductor (“3-wire”)

  cable, connect the neutral at

  switch loop, shown in the drawing above right,

  the power source, and then

  can probably be found in 90 percent of homes

  cap off the neutral in the

  but has been superseded by changes in the elec-

  switch box. Because 3-wire

  trical code. The second way to wire a switch

  cable has both a black and red

  loop, shown in the drawing at right, conforms

  conductor, there is no need to

  to the 2011 NEC and should be used for new

  re-identify the white

  installations.

&nbs
p; conductor as hot, as was done

  in the old method, above.

  electrical Wiring

  305

  dimmer leads

  It’s critical which circuit wires you attach to

  dimmer leads. so during the rough-in stage, dis-

  tinguish which wire is the switch leg and which

  is the incoming hot wire for each single-pole

  dimmer that you install. to distinguish these

  wires, many electricians wrap the wires together

  and bend back the switch leg wire. typically, the

  red dimmer lead attaches to the switch leg wire,

  and the black dimmer lead attaches to the

  incoming hot wire. or slip a short sleeve of cable

  sheathing back onto the stripped wires and use a

  1. Dimmer specifics vary from one

  felt-tipped marker to label what each wire does.

  manufacturer to the next. read

  installation instructions beforehand:

  see the photo on the bottom of p. 291.

  It’s critical which circuit wires you

  attach to dimmer leads.

  the historical method. Before the code

  2. Prepare stranded dimmer leads by

  changed it was common to run a single length of

  twisting them to compact them,

  12/2 or 14/2 cable as a switch loop. This means

  before attaching them to solid­wire

  bringing the power down from the fixture to and

  circuit wires.

  through the switch and then back up to the fix-

  ture. As such, the black wire in the 12/2 or 14/2

  switch loop functions as the incoming hot wire,

  and the normally neutral white wire acts to

  return the power to the fixture. Here, the white

  wire is actually a hot wire and is marked to iden-

  tify it as such.

  At the outlet or fixture box, splice all the

  grounds together. Attach the source neutral wire

  to the fixture neutral wire. Attach the source hot

  wire to the white wire (taped black) of the switch

  loop. Last, connect the switch loop black wire to

  the black fixture wire (see p. 314 for more).

  3. Cap any lead you won’t connect.

  4. Attach the ground wire, then connect the red lead to

  Note: Here, for convenience, we bend the rule

  the switch.

  of using a white wire only as a neutral wire and

  instead wind black tape on each end of the white

  P r O t I P

  wire to show that—in this case—the white wire is

  being used as a hot wire.

  unless manufacturer’s

  At the switch, start by stripping and looping

  instructions say otherwise,

  the wire ends in the switch loop. Next, tape the