chapter 2

• Electric Conductors


  Substances or materials used to convey or allow the flow of electric current
• Insulators


  Substances or materials that resist the flow of electric current
• Good electric conductors


  • Silver
  • Copper
  • Aluminum
  • Nickel
  • Brass
  • Zinc
  • Platinum
  • Iron
  • Lead
  • Tin
• Various kinds of insulators


  • Rubber
  • Porcelain
  • Varnish
  • Slate
  • Glass
  • Mica
  • Latex
  • Asbestos
  • Paper
  • Oil
  • Wax
  • Thermoplastic
• Resistance


  Due to the friction between the flow of current and the conductor as well as the material
• There is no such thing as a perfect conductor or a perfect insulator, because conductors, insulators, and resistors are all sensitive materials</b>
• Good conductors


  Substances with extremely low resistance to current flow
• Wires


  Electrical conductors 8 mm~ (AWG No. 8) and smaller in sizes
• Cables


  Larger than wires
• Types of wires and cables

  • Stranded wire
  • Solid wire
• Stranded wire


  • Consists of a group of wires twisted to form a metallic string
  • Circular mil area is found by multiplying the circular mil area of each strand by the total number of strands
• Cord


  Insulated stranded wire
• Mil


  Equal to 1/1000 of an inch, used to describe or measure a round wire diameter
• Ampacity


  The ability of the wire or conductor to carry current without overheating
• Voltage drop in wire

  Circuit current x Resistance of wire
• Power loss in wire

  1. Circuit current x Voltage drop

  2. I x (I x R)

  3. I^2 R
• Power loss is equal to the conductor's resistance times the current squared, and the power loss being converted into heat must be dissipated
• A larger wire diameter can safely carry more current in proportion to its weight
• The use of copper wire is most accepted
• Conductor ampacity


  Determined by the maximum operating temperature that its insulation can withstand continuously without heating
• Current flow and conductor's resistance

  Normally generates heat
• Operating temperature


  Depends upon the amount of current flow, wire resistance, and environment
• Ampacity or ability of the conductor to carry load increases as the size of conductor increases
• Derating of conductors ampacity


  The full amount of allowable ampacity is reduced to a certain percentage due to the environmental condition it is exposed to and the number of wires placed inside the conduit
• The current rating of wire in a free air environment is higher than those placed inside the conduit
• Raceway


  Channels or wiring accessories designed for holding wires, cables or busbars that are either made of metal, plastic, or any insulating mediums
• Common types of raceways for household wiring installations

  • Conduits
  • Connectors and other accessories
• Types of conduit pipe

  • Metallic (steel pipes, aluminum, etc.)
  • Non-metallic (plastic and the like)
• Types of conduit based on make

  • Rigid metal
  • Flexible metal
  • Rigid non-metal
  • Flexible non-metal
• Purposes of electrical conduits

  • Provide a means for running wires from one point to another
  • Physically protect the wires
  • Provide a grounded enclosure
  • Protect the surroundings against the effect of fault in the wiring
  • Protect the wiring system from damage by the building and the occupants
  • Protect the building and the occupants from damage by the electric system
• Connector


  A metal sleeve usually made of copper that is slipped over and secured to the butted ends of conductors in making a joint
• Connector


  Otherwise called splicing sleeve
• Outlet


  A point in the wiring system at which current is taken to supply utilization equipment
• Different kinds of outlets

  • Convenience outlet or attachment cap
  • Lighting outlet
  • Receptacles outlet
• Convenience outlet or attachment cap


  A device that by insertion into a receptacle establishes connection between the conductor of the flexible cord and the conductors connected permanently to the receptacle
• Lighting Outlet


  An outlet used for direct connection to a lamp holder, lighting fixture, or a pendant cord, terminating in a lamp holder
• Receptacle Outlet


  An outlet where one or more receptacles are installed
• Other wiring accessories

  • Junction box
  • Receptacles
  • Pull box
  • Switches
• Junction Box is not an outlet. By definition, it does not supply current to utilization device.
• Outlet refers only to the box itself. It does not include the items. The receptacle device is not an electrical load but rather an extension of the box wiring.