Renovation 4th Edition

by Michael Litchfield

  Hold the saw at a low angle; you’ll be less likely

  to break blades or cut into studs. Using a ham-

  mer, gently crush the plaster between the lines.

  Use a utility bar (flat bar) to pry out the lath

  strips or drywall section. If you expose any cables

  in the walls, use an inductance tester to make

  sure they’re not hot. Next, drill through the studs

  so you can run cable in the trench. Wherever

  there’s an outlet indicated, expand the trench

  width to accommodate the boxes.

  6. Pull out any nails still stuck in the

  Finally, pull any lath or drywall nails from

  studs; this will make later repairs

  stud edges. They’re easy to overlook because

  easier.

  they’re small; if you pull them now, patching the

  trench will go smoothly.

  5. Use a hammer and a flat bar to pry the lath free from

  the studs. Work slowly to minimize damage.

  electrical Wiring

  297

  1. for metal boxes, start by

  2. Screw the box to the side of a stud.

  3. for the best appearance, install side­by­side outlets at

  removing knockouts and then insert a

  the same height. The piece being plumbed is a data ring,

  connector.

  which is essentially a face plate without a box. Data lines

  have such low voltage that they don’t need to be

  protected in an outlet box.

  4. run cable to each box.

  5. feed cable through cable connectors until you have a 6. Staple the cable within 12 in. of

  generous amount to work with—9 in. or 10 in. is plenty.

  each box. Here, the electrician drives

  staples to the underside of a rough

  windowsill.

  Pulling Cable To reTrofiT boxes

  room to loop the cable and staple it to a stud, it’s

  acceptable to staple it to other solid framing,

  Once you’ve cut a wiring trench and drilled the

  such as the underside of a windowsill.

  holes, installing the boxes and pulling cable is

  fairly straightforward. If you’re installing metal

  sTriPPing nM Cable

  boxes, remove knockouts and insert cable con-

  WiTh a Cable riPPer

  nectors into their openings. Then screw boxes to

  studs; screwing is less likely to damage nearby

  Most professional electricians favor utility knives

  finish surfaces. Be sure that the box will be flush

  for removing plastic sheathing. But non-pros

  to finish surfaces or, if you’ll install plaster rings

  should use a cable ripper to avoid nicking wire

  later, flush to the stud edge. Whenever you install insulation. Because the ripper’s tooth is inten-

  boxes side by side—as with the outlet and low-

  tionally dull (so it won’t nick wire insulation), it

  voltage data ring shown—install them plumb and usually takes several pulls to slit the sheathing

  at the same height.

  completely. Once that’s done, pull back the

  Installing cable in remodels can be tricky

  sheathing and the kraft paper and snip off both,

  because space is tight and you must avoid bend-

  using diagonal cutters.

  ing cable sharply, which can damage wire insula-

  Because cable clamps grip sheathing—not

  tion. Install nail plates wherever the edge of the

  individual wires—there should be at least 1⁄4 in.

  hole is less than 11⁄4 in. from the stud edges. Feed of sheathing still peeking out from under cable

  cable through the cable connectors into the

  clamps when you’re done. If you leave more than

  boxes. Finally, staple the cable to the framing

  a 1⁄2 in., you make working with the wires more

  within 8 in. of a single-gang box without clamps,

  difficult. If you didn’t tighten cable clamps earlier,

  or within 12 in. of other boxes. If there’s not

  do so now.

  298 Chapter 11

  If there is only one cable entering a box, just

  P r O t I P

  cut individual wires to length—typically, 6 in. to

  8 in. If there’s more than one cable, you’ll add a

  Test new outlets before

  6-in. pigtail to each wire group.

  patching walls or ceilings. if the

  outlet’s not correctly wired, you

  sPliCing Cable

  can repair it without having to

  Electricians call the last stage of rough wiring

  rip out a newly installed patch to

  making up a box. After removing sheathing from

  get access.

  cables, rough-cut individual wires about 8 in.

  long, group like-wires, and, to save time later,

  splice all wire groups.

  Typically, electricians start by splicing the

  ground wires, which are usually bare copper. (If

  they’re green insulated wires, first strip approxi-

  mately 3⁄4 in. of insulation off their ends.) If you

  use standard wire connectors, trim the ground

  wires and butt their ends together, along with a

  6-in. pigtail, which you’ll connect later to the

  green ground screw of a receptacle.

  However, many pros prefer to twist the

  ground wires together, leave one ground long,

  and thread it through the hole in the end of a

  special wire connector (see the top photo on

  p. 300). If the box is metal, first bond the ground

  A cable ripper slits sheathing without damaging

  A crimp tool may be used instead of a

  individual wire insulation. Use diagonal cutters to

  wire nut to splice ground wires.

  wire to the box, using a grounding clip or a

  cut free sheathing.

  grounding screw.

  Splicing hot and neutral wire groups is essen-

  tially the same. Trim hot wires to the same

  length. Strip 3⁄4 in. of insulation off the cable

  wires and the pigtail, and use lineman’s pliers to

  twist the wires. Screw on a wire connector. If a

  box has more than one circuit in it, all the

  grounds must be spliced together, but the

  neutrals of the different circuits must be kept

  separate.

  Once the wire groups are spliced, gently

  accordion-fold the wires back into the box until

  you’re ready to wire switches and receptacles.

  Wiring Receptacles

  The long wire of the spliced grounds is looped beneath the Strip about 1⁄2 in. of insulation from

  grounding screw in a metal box.

  wire ends, and splice like­wires

  Wiring an electrical device is considered part of

  together.

  finish wiring—also called the trim-out stage—

  when finish walls are in place and painted. At the

  trim-out, everything should be ready so that the

  electrician needs only a pair of strippers and a

  screwdriver or screw gun.

  All work in this section must be done with

  power off: Use a voltage tester to be sure.

  Wiring a duPlex reCePTaCle

  The duplex receptacle is the workhorse of house

  wiring. Receptacles are so indispensable to mod-

  ern life that code dictates that no space along a

  wall in a habitable room should be more than

 
6 ft. from a receptacle and any wall at least 2 ft.

  for the two receptacles that will be

  fold the wires carefully into the box, and install a mud

  wide must have a receptacle.

  installed in this box, two sets of

  ring. This box is ready for a rough­in inspection.

  pigtails are needed.

  electrical Wiring

  299

  The rough-in inspection

  at the rough-in stage, inspectors will look for a few key signs of a job well done:

  cables properly sized for the loads they’ll carry; the requisite number and type of

  outlets specified by code; cables protected by nail plates as needed; neat, consis-

  tent work throughout the system; and, above all, ground wires spliced and, in metal

  boxes, bonded to the box with a ground screw. if grounds aren’t complete, you won’t

  pass the rough-in inspection. remember the inspection is usually a spot-check, so

  do not count on the inspector to catch every mistake or omission.

  at this inspection, only grounds need to be spliced. but since you’ve got the

  tools out, it makes sense to splice neutrals in a group, and continuous hot wires

  1. When wiring a receptacle, electricians usually start

  with the ground. “Wiring in an Orderly Way” on p. 301

  (those not attached to switches).

  explains why.

  When all splices are complete, carefully fold the wire groups into the box. When

  you come back to do the trim-out stage, simply pull the wires out of the box, con-

  nect wires to devices, and install devices and cover plates.

  Connecting circuit wires to a main panel or subpanel is the very last step of an

  installation. as noted throughout this book, you should never handle energized

  cables or devices. if you are testing circuits, shut off power to manipulate the wir-

  ing and set up to test, power up and then test, and then cut the power to continue

  the work. remember, 120 volts can kill.

  receptacle in Midcircuit

  2. next, connect the neutral­wire pigtail to a silver screw

  terminal. Screw terminals are generally a more secure

  zzzzzz

  connection than using a spring back­wire hole terminal

  on a device.

  Incoming

  Outgoing power

  power

  (downstream)

  Twist-on

  wire connectors

  Hot

  pigtail

  3. finally, tighten the hot­wire

  4. When you finish wiring a

  Neutral

  pigtail

  pigtail wire to a brass screw

  receptacle, carefully fold wires into

  terminal. Make the connections

  the box so the face of the device will

  good and tight.

  be parallel to the wall. Crooked

  devices suggest sloppy work.

  Ground

  S a f e t y a l e r t

  The ground screw must compress

  the ground wire evenly. never

  By splicing like-wire groups and running pigtails (short wires)

  cross the ground wire (or any

  to the receptacle in this conventional method, you ensure

  wire) over itself because the

  continuous current downstream.

  5. Push in the receptacle, too, before

  screw would touch only that

  screwing it to the box. That is, don’t

  high spot.

  use screws to pull the receptacle into

  a packed box—you might strip the

  threaded screw holes of a plastic box.

  300 Chapter 11

  When a duplex receptacle is in the middle of

  receptacle at end of Circuit

  a circuit, there will be two 12/2 or 14/2 cables

  entering the box—one from the power source

  and the other running downstream to the next

  zzzzzz

  Incoming

  outlet.

  power

  To ensure continuity downstream, all wire

  groups will have been spliced with wire connec-

  Because there

  tors during the rough-in stage. A pigtail from

  are no receptacles

  each splice will need to be connected to a screw

  downstream, attach

  all wires directly to

  terminal on the receptacle. Unless the small tab

  the device.

  between screw pairs has been removed, you need

  to attach only one conductor to each side of the

  receptacle.

  Loop and install the ground wire to the recep-

  tacle’s green grounding screw first. Place the loop

  clockwise on the screw shaft so that when the

  screw is tightened down, the screw head will grip—

  rather than dislodge—the wire.

  Next, loop and attach a neutral conductor to a

  silver screw terminal. (Some electricians also

  tighten down the screw that isn’t used as a matter

  of good practice.) Then flip the receptacle over to

  access the brass screw terminals on the other

  side. If a looped wire end is too wide, use needle-

  nose pliers to close it.

  Screw down the brass screw so that it grips

  the hot wire. Pros frequently use screw guns

  for this operation, but weekend electricians

  Two-slot receptacles

  should tighten the screw by hand to ensure a

  solid connection.

  receptacles with only two slots are ungrounded. because they are fed by two-wire

  Push the wired receptacle into the box by

  cable without a ground wire, they are inherently less safe than three-slot recepta-

  hand, keeping the receptacle face parallel to the

  cles fed with a grounded cable. if existing cables and receptacles are correctly wired

  wall. You can hand-screw the device to the box,

  and in good condition, most codes allow you to keep using them. should you add

  but if you take it slow and use a fresh bit, a cord-

  circuits, however, code requires they be wired with grounded cable (12/2 w/grd or

  less drill/driver is much easier. Finally, install a

  14/2 w/grd) and three-slot receptacles.

  cover plate to protect the electrical connections

  replacing a two-slot receptacle with a gfCi receptacle can be a cost-effective

  in the box and to prevent someone from inadver-

  way to add protection to a two-wire circuit. There will still not be a ground wire on

  tently touching a bare wire end or the end of a

  the circuit, but the gfCi will trip and cut the power if it detects a ground fault. you

  screw terminal.

  can wire the gfCi receptacle to protect just that outlet or that outlet and all outlets

  downstream (away from the power source).

  Wiring

  Note: if one slot of a two-slot recepta-

  In an orderly Way

  cle is longer, the receptacle is polarized.

  That is, a receptacle’s brass screw terminal

  any habit that increases your safety is worth

  will connect to a hot wire and, internally,

  adopting. When connecting wires to devices,

  to the hot (narrow) prong of a polarized

  most electricians connect the ground wire first,

  two-prong plug. The receptacle’s silver

  then the neutral wire, and then the hot wire.

  screw terminal connects to neutral wires

  When disconnecting wires, they reverse the

  and,
internally, to the neutral (wide) prong

  order: disconnect the hot first, then the neutral,

  of a polarized plug.

  then the ground wire. Because the ground wire

  offers the lowest impedance path to ground, it

  makes sense to leave it connected as long as

  possible. Follow this order even if you’re work-

  receptacles with two slots (instead of three)

  ing on circuits that are disconnected: as veteran

  are non­grounding types. If the two slots are

  the same length, the receptacle is also nonelectricians say, “treat every conductor as if it

  polarized and should be replaced with a

  were live and you’ll stay alive.”

  polarized non­grounding receptacle.

  electrical Wiring

  301

  When a receptacle is at the end of a circuit—

  gfCi receptacle, single-location Protection

  where only one cable feeds an outlet—there’s no

  To devices

  need for pigtails. Just attach incoming wires

  zzzzzz

  downstream

  directly to the receptacle as shown in the illustra-

  Incoming

  power

  tion on p. 301. As with pigtail wiring, connect

  the ground wire first, then the neutral, then the

  Neutral

  hot wire.

  wires spliced

  Hot

  wires spliced

  Wiring a gfCi reCePTaCle

  When wiring a GFCI receptacle, it’s important

  to connect incoming wires (from the power

  source) to the terminals marked “line” on the

  Line

  back of the receptacle. To distinguish line and

  brass

  load wires during rough-in, write each term on

  small pieces of the cable sheathing and slip them

  over the appropriate wires before folding them

  into the box.

  Line silver

  Ground

  The GFCI shown here is something of a

  wires spliced

  hybrid because it allows you to loop stripped

  Ground screw

  wire ends around the screw terminals or to leave

  the stripped wire ends straight and insert them

  This configuration provides GFCI protection at one location

  into holes in the back of the device—also known

  —say, near a sink—while leaving devices downstream unprotected.

  as back-wiring. In this case, back-wiring is

  Here, splice hot and neutral wires so the power downstream is

  continuous and attach pigtails to the GFCI's "line" screw terminals.

  acceptable because you must tighten screws on

  With this setup, receptacle use downstream won’t cause nuisance