Renovation 4th Edition

by Michael Litchfield

  American wire gauge (6AWG) copper. Ground

  current leaks and shut off power

  and should be replaced by an electrician.)

  rods are typically

  almost instantaneously. They are

  1⁄2-in. or 5⁄8-in. copper-clad steel

  If your home has a fuse panel instead, remove especially important in kitchens

  rods at least 8 ft. long. The Ufer or concrete-

  the fuse that controls the circuit, and tape a sign

  and bathrooms, where water and

  encased electrode is the preferred grounding

  to the panel cover warning that the fuse should

  dampness increase the potential

  electrode, and must be used if new concrete foot-

  not be reinstalled until work has been completed. for shocks.

  ings are poured.

  (You can also lock the panel cover.) Partially

  unscrewing a fuse is not a solution because the

  gfCis

  fuse body is still in contact with the socket and

  Ground-fault circuit interrupters (GFCIs) are

  possibly could be jiggled or screwed in enough to

  sensitive devices that can detect very small cur-

  reenergize the circuit. Remove the fuse. Likewise,

  rent leaks and shut off power almost instanta-

  if circuits are controlled by cartridge fuses, pull

  neously. The NEC now requires GFCI protection

  the cartridge or cartridge block out of the panel.

  on all bathroom receptacles, all receptacles serv-

  In any case, once you’ve cut off the power,

  ing kitchen counters, receptacles within 6 ft. of a

  shut the panel cover and tape a sign to it, telling

  sink other than in kitchens, all outdoor recepta-

  others to stay out. Otherwise, someone not aware

  cles, all unfinished basement receptacles, all

  of the situation could flip the switch on, energiz-

  garage receptacles, and all receptacles near pools, ing the circuit you’re working on.

  PAnEl SAfETY

  Once the power is off, post a warning

  sign to prevent others from turning

  the power back on while you’re still

  In a breaker box, simply flip the relevant breaker to the

  If you’re working on a fuse panel, unscrew and remove the working on a circuit. Even better, lock

  off position.

  fuse that protects the circuit you’re working on.

  the panel.

  electrical Wiring

  267

  USInG A vOlTAGE TESTEr

  When using any type of voltage

  When testing a receptacle, insert the tester in all slots and . . . remove the cover plate and unscrew the device from tester, always test the tester on an

  touch it to the plate screw as well. If the tester does not

  the box. Then, being careful not to touch the terminal

  outlet that you know is hot—to be

  light, the power is probably off. But to be doubly sure . . .

  screws, wires, or box, apply the tester to all conductors. If

  sure it is operating properly. Here, the

  the tester still doesn’t light, it’s safe to work in the box.

  glowing point of a non­contact

  tester indicates voltage is present.

  TesTing WiTh a

  Planning an

  non-ConTaCT TesTer

  Electrical Remodel

  A non-contact tester is a popular battery-operated Being detail oriented is as important to planning

  voltage tester that is reliable, inexpensive, and

  as it is to installation. When you plan a wiring

  small enough to fit in a shirt pocket. Its plastic

  project, be methodical: Assess the existing sys-

  tip glows (and it may beep, depending on the

  tem, calculate electrical loads, check local codes,

  model) when it is brought close to or touched to a and draw a wiring floor plan.

  hot (energized) screw terminal, receptacle slot,

  If you are only replacing existing devices—

  wire, or other item. Each time you use a non-

  changing a light fixture, replacing a faulty switch,

  contact tester—or any voltage tester—test that it’s or upgrading a receptacle, for example—you sel-

  functioning properly first on a receptacle that

  dom need a permit from the local building

  you know is hot, and test it afterward as well.

  department. However, if you extend or add any

  After shutting off power at the panel, insert

  circuit, you must get a permit.

  the tester tip into the narrow (hot) slot of a recep-

  Most local electrical codes are based on the

  tacle. If the tester tip does not glow, there is prob-

  NEC. When it’s necessary to pull a permit, local

  ably no voltage present. To be sure, insert the tes-

  code authorities will want to approve your plans

  ter tip into the receptacle’s wide (neutral) slot and and later inspect the wiring to be sure it’s correct.

  into the grounding slot. This should protect you

  Don’t short-cut this process: Codes and inspec-

  in case the receptacle was incorrectly wired.

  tions protect you and your home.

  If you need to remove the receptacle—say, to

  Whatever the scope of your project, if you

  replace it—remove the cover and test one more

  work on existing circuits, first turn off the power,

  time. Being careful not to touch the sides of the

  test to be sure it’s off, and tag or lock the panel.

  receptacle, unscrew the two mounting screws

  holding the receptacle to the outlet box. (If the

  insPeCTing The fuse

  box is metal, avoid touching it, too.) Grasp the

  box or breaker Panel

  mounting straps, and gently pull the receptacle

  out of the box. First, touch the tip of the tester to

  By looking at the outside of the service panel and

  the hot (black) wire and to the brass screw termi-

  wiring that’s exposed in the basement and attic,

  nal, then touch the tip to the white (neutral) wire you can get a basic overview of the system’s con-

  and to the silver screw terminal. Also test the

  dition. If the panel has unused breaker spaces

  green (grounding) terminal and wire. If the tester and the wiring insulation is in decent shape, you

  tip does not glow, it’s safe to handle the recepta-

  can probably continue using it and safely add an

  cle and the wires feeding it.

  outlet or two. However, if the system seems

  A non-contact tester will often glow when its

  unsafe or inadequate, hire a licensed electrician

  tip is merely near a hot wire—that is, it can

  to open the panel and do a more thorough exami-

  “read” current through a wire’s insulation or

  nation.

  through a cover plate. Thus you can sometimes

  Here’s what to look for:

  detect electrical current at a switch or fixture

  Start your investigation at the fuse box or

  without removing the outlet cover.

  breaker panel. You can learn a lot about the con-

  dition of the system by examining the outside

  268 Chapter 11

  of the service box. Examining the inside of a

  Here, again, have an electrician examine the cir-

  panel or fuse box is best left to a licensed electri-

  cuits for damage to the wire insul
ation.

  cian, however.

  Panel covers that don’t fit, have gaps, or are

  Rust and corrosion on the outside of a service missing are unsafe. So, if you see covers that

  box or on the armored cable or conduit feeding it have been cut to fit a breaker, housing knockouts

  can indicate corroded connections inside. Faulty

  that are missing, bus bars that are visible when

  connections can lead to arcing (sparks leaping

  the panel cover is on, or mismatched compo-

  gaps between wires) and house fires, so have a

  nents, hire a licensed electrician to assess and

  licensed electrician replace the fuse box or panel. correct those problems. Some older brands of

  Likewise, if you see scorch marks on breakers or

  panels and breakers, such as Federal Pacific®

  a panel, have a pro examine it.

  and Zinsco®, have a host of well-documented

  Melted wire insulation is a sign either of an

  failures and so should be carefully checked and,

  overheated circuit—usually caused by too many

  where necessary, replaced.

  appliances in use at the same time—or of a poor

  Missing cable connectors or unfilled knock-

  wire connection in which arcing has occurred. In outs enable mice and vermin to enter the panel

  the first case, a homeowner typically installs an

  and nest in it, which can be a fire hazard.

  oversize fuse or breaker to keep an overloaded

  Missing connectors also allow cables to be

  circuit from blowing so often, but this “remedy”

  yanked, stressing electrical connections inside

  exceeds the current-carrying capacity of the wire. the panel. A missing cable clamp may also allow

  The wire overheats and melts the insulation, which the sharp edge of the panel to slice through ther-

  can lead to arcing, house fires, or—if someone

  moplastic cable sheathing, which could energize

  Unsafe! All cables entering a panel

  touches that bare copper wire—electrocution.

  the panel (if the grounding of the system is not

  must be protected by a cable clamp

  An oversize fuse may not melt wires where

  correct) and electrocute anyone who touches it.

  inserted into a panel knockout. Sharp

  you can see them, but it may have damaged wire

  A properly grounded panel will have a large

  panel edges could slice the insulation

  of this unprotected cable. Also, for

  insulation in a place you can’t see. Have an elec-

  grounding wire running from the panel to a

  the cables, the sheathing must extend

  trician inspect the electrical system. Installing

  grounding electrode (which could be a metal

  at least ¼ in. into the box.

  type-S fuse socket inserts can prevent overfusing.

  underground water pipe, a ground rod driven

  “Pennying” a fuse is another unsafe way to

  into the earth, or a Ufer electrode). For the entire

  deal with an overloaded circuit that keeps blow-

  electrical system to be grounded, there must be a

  ing fuses. In this case, someone unscrews a fuse,

  continuous ground wire or other effective

  inserts a penny or a blank metal slug into the bot- grounding path running from each device or fix-

  tom of the socket—a dangerous act in itself—and ture to the service panel and, by extension, to the

  then reinstalls the fuse. The penny allows current grounding electrode. Cold-water and gas pipes

  to bypass the fuse and the protection it offers.

  must also be connected (bonded) to the ground-

  ing bus in the panel.

  a 30-year Pro’s Take on rewiring

  if the wiring in an older home appears to be sound and in good repair (see the warn-

  ing signs below) it’s probably ok to continue using it, even though it may not meet

  code requirements for a new installation. if you are planning to gut the house com-

  pletely, it makes sense to rip out all the old wiring and completely rewire the house. if

  you’re remodeling only part of the house, leave most of the old wiring in place if it is

  sound and spend your money rewiring the kitchen, baths, and laundry circuits. That

  will give you more bang for your buck.

  however, you should replace old wiring that’s unsafe. if you observe any of these

  conditions, the wiring should be replaced:

   Circuits that have been extended improperly, as evidenced by loose connections,

  unprotected splices, or arcing.

   knob-and-tube wiring whose insulation has deteriorated or that has been dam-

  aged. also, if knob-and-tube wiring in the attic has been covered with loose-fill insu-

  lation or insulation batts, that is a serious code violation that could lead to overheat-

  This 30­amp main switch and fuses was the panel for

  ing and fire danger.

  the whole house. It has seen better days. Even if it were

   Circuits wired with unsheathed wires (other than properly done knob-and-tube)

  safe, it would be dramatically undersized for today’s

  rather than with sheathed cable or conduit.

  electrical needs.

  electrical Wiring

  269

  ungrounded outlets

  You can continue using two-slot, ungrounded

  receptacles on general-use circuits as long as

  the wires are in good condition and the connec-

  tions are correctly made. most new lamp and

  appliance plugs are double-insulated and are

  suitable for use with ungrounded receptacles.

  however, if you want to use appliances or tools

  with three-pronged plugs or a surge protector at

  the location, you must upgrade to a grounded

  circuit. putting a two-pronged adapter on a

  three-pronged plug is unsafe.

  Unstapled cable and unsecured

  boxes can be inadvertently yanked

  assessing The

  and stress electrical connections. If

  CondiTion of Wiring

  you see work this sloppy, suspect

  substandard wiring throughout

  Cables may be visible as they near the service

  the house.

  panel and as they run through attics and base-

  ments. If there are covered junction boxes, care-

  fully remove the covers and examine the wire

  splices inside—without touching them. You can

  also turn off power and pull a few receptacles out

  to better examine the wires.

  Deteriorated sheathing is a potential shock

  hazard, so note brittle fiber insulation and bare

  wire, but avoid touching it. If cable sheathing has

  been chewed on by mice, rats, or squirrels the

  cable should be replaced.

  NM cable (cable protected by nonmetallic

  sheathing) must be stapled within 8 in. of single-

  gang boxes that don’t have cable clamps, and

  within 12 in. of other boxes, and supported by

  stapling or another method at least every 41⁄2 ft.

  (54 in.). A cable running through a drilled hole is

  considered supported. Sagging wire is hazardous

  because it can get inadvertently strained, jeopar-

  dizing electrical connections. Likewise,

  all boxes must be securely mounted. All NM

  cable entering metal boxes must be gripped

  b
y cable clamps. Single-gang plastic boxes do

  not require the strain relief of cable clamps, but

  double-gang (and larger) plastic boxes have inte-

  gral plastic tension clips that afford some strain

  relief on cable.

  Small-gauge aluminum wiring (10 or

  12 gauge) is a fire hazard unless it is correctly

  Some old houses still have knob­and­

  spliced to a copper wire with a COPALUM® con-

  tube wiring, which doesn’t necessarily

  nector or terminated to CO/ALR-rated outlets

  need to be replaced. Have it tested to

  and switches. If it is incorrectly terminated in a

  make sure it’s still in good shape.

  copper-rated only device, the two metals will

  270 Chapter 11

  expand and contract at different rates each time

  the circuit is under load. This can lead to loose

  assessing a Circuit’s Capacity

  connections, arcing, overheating, and house fires.

  Aluminum to aluminum splices require special

  To recap briefly, electricity, impelled by voltage, flows from the power source.

  splicing techniques, either COPALUM connectors

  ( Amperes are the rate of electron flow.) along the way (at outlets), it encounters

  or another listed and approved method.

  resistance and does work. ( Watts are a measure of power consumed.) it then returns

  Wire splices (whether copper to copper, cop-

  to the power source, its voltage reduced or spent.

  per to aluminum, or aluminum to aluminum)

  or, expressed as mathematical formulas:

  must be housed within a covered junction box or

  watts = voltage x amperes

  outlet box. Wires that are spliced outside a box or

  inside an uncovered box can be a fire hazard

  amperes = watts ÷ voltage

  because of the dangers of arcing. Loose connec-

  To determine the capacity of a circuit you want to extend, identify the circuit

  tions not contained in a cover box can easily

  breaker controlling the circuit and note the rating of the breaker. if it’s a general-

  ignite combustibles nearby because arcs

  purpose circuit, the breaker will probably be 15 amp or 20 amp. a circuit controlled

  approach 2,000°F.

  by a 15-amp breaker has a capacity of 1,800w (15 amp x 120v); one controlled by a

  Knob-and-tube wiring, although outdated,

  20-amp breaker has 2,400w.

  is usually safe unless individual wire insulation

  The total wattage of all loads on the circuit (including the extension) must