ELECTRICAL WIRING

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ELECTRICAL WIRING

• WIRING BASICS

Written by Bobby Joslin
GA Ag Ed Curriculum Office To accompany the
Georgia Agriculture Curriculum Lesson
01422-6.2 July 2002
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STANDARDS FOR SAFETY

• National Electrical Code
• Local Electrical Code
• Power Company Requirements
• Underwriters Laboratory (UL)

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NATIONAL ELECTRICAL CODE

• History of the National Electrical Code
• Purpose of the NEC
• How Often the NEC is updated
• Scope of the NEC
• Enforcement of the NEC
• Using the NEC

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LOCAL ELECTRICAL CODES

• Local authorities may adopt NEC
• May adopt NEC with modifications
• Local wiring permits and inspections

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POWER COMPANY REQUIREMENTS
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UNDERWRITERS LABORATORY

• UL Listed assures product meets minimum safety
  standards
• UL Listed does not mean that product is safe for
  all installations
• UL Listed is not an indication of quality

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BRANCH CIRCUITS

• Definition of circuit
• Definition of branch circuit

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BRANCH CIRCUITS IN A RESIDENCE

• Individual Circuit
• Small Appliance Circuit
• Laundry Circuit
• Bathroom Circuit
• General Purpose Circuit

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INDIVIDUAL CIRCUIT

• Supplies only one outlet or piece of equipment
• Motors 1/2 horsepower or larger
• All 240 volt equipment
• Other equipment such as furnace fan, freezer,
  television, computer

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SMALL APPLIANCE CIRCUIT

• Serves receptacles for small appliance loads
• At least two required by NEC
• Must be 20 ampere circuits
• No lighting outlets
• Cannot serve any other room in house

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LAUNDRY CIRCUIT

• Serves only receptacles in laundry room
• At least one required by NEC
• Must be 20 ampere circuit
• May not have lighting outlets
• May not serve outlets in any other room of house

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BATHROOM CIRCUIT

• Circuit to serve receptacles in bathroom
• At least one required by NEC
• Must be 20 ampere circuit
• May not serve lighting outlets
• May not serve any other room in house

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GENERAL PURPOSE CIRCUITS

• Serve all lighting outlets in home
• Serve all receptacles not on one of the other
  types of circuits
• May be 15 or 20 ampere (20 ampere preferred)
• Allow at least one general purpose circuit for
  every 500 square feet of floor space in house

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Determining the Kind, Number and Location of
Outlets and Switches in a Wiring System
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Lighting Outlet Requirements

• At least one wall switch controlled outlet in
  every habitable room in house
• Stairways consisting of 6 or more steps must have
  lighting outlet that is wall switch controlled at
  both floor levels
• Attics, underfloor space, utility room and
  basement requirements

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RECEPTACLE OUTLET REQUIREMENTS

• No point along the floor line in any wall space
  may be more than 6 feet from a receptacle in
  kitchen, family room, dining room, living room,
  den, sun room, bedroom, recreation room, or
  similar room
• (Receptacles must be no farther than _____ feet
  apart.)

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RECEPTACLE REQUIREMENTS

• A receptacle must be installed at each kitchen
  and dining area counter space if the space is
  wider than 12 inches
• No point along the wall line of a kitchen counter
  may be more than 24 inches from a receptacle
• (Receptacles must be no farther than _____
  inches apart)

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RECEPTACLE REQUIREMENTS

• At least one receptacle is required within 36
  inches of the outside edge of each basin in
  bathrooms.
• All receptacles in bathrooms must have ground
  fault circuit interrupter protection

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RECEPTACLE REQUIREMENTS

• At least one outdoor receptacle is required
• All outdoor receptacles must have GFCI protection
• Outdoor receptacles must be installed in
  waterproof boxes

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RECEPTACLE REQUIREMENTS

• At least one receptacle is required in the
  laundry area
• At least one receptacle is required in a
  basement. All general use receptacles in an
  unfinished basement must have GFCI protection

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RECEPTACLE REQUIREMENTS

• At least one receptacle is required in hallways
  10 feet or more in length
• Effective January 1, 2002, all receptacles in a
  bedroom must have arc-fault circuit interrupter
  protection

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RECOMMENDATIONS FOR OUTLETS AND SWITCHES

• Receptacles should generally be located
  approximately above floor line
• Receptacles preferably should be located near the
  ends of wall space
• Lighting outlets in closets should be wall switch
  controlled
• Pull chain lighting outlets should be minimized,
  if used at all

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RECOMMENDATIONS FOR OUTLETS AND SWITCHES

• Wall switches should be generally be located
  approximately 48 inches above the floor line and
  on the latch side of doors
• Three and four way switches should be used to
  control lights in locations such as rooms having
  more than one entrance, stairways, halls,
  basement, covered walkways between the house and
  garage, etc.

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Determining the Number of Outlets On a General
Purpose Circuit

• For calculation purposes, estimate a load of at
  least 1.5 amps per outlet on the circuit
• To determine the maximum number of outlets on a
  20 amp general purpose circuit 20 amps (circuit
  rating) ? 1.5 amps 13 outlets (maximum)
  on the circuit
• Maximum number of outlets on a 15 amp general
  purpose circuit ________?

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SELECTING SERVICE ENTRANCE EQUIPMENT

• Service conductors
• Service mast
• Entrance head or weather head
• Meter base
• Service entrance cable

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Service Entrance Panel

• Purpose
• Factors to consider when selecting the service
  entrance panel
• Type of panel
• Size or ampere rating
• Circuit capacity or number of spaces for
  connecting circuits

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PROVIDING OVERCURRENT PROTECTION

• Providing a means to interrupt an electrical
  circuit when the amperage in the circuit becomes
  excessive
• Reasons for providing overcurrent protection

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SIZE OF OVERCURRENT PROTECTION DEVICE TO USE
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PLANNING ELECTRICAL CIRCUITS

• Wiring symbols

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CLASSIFICATION OF CONDUCTORS

• Grounded conductor
• Ungrounded conductor
• Equipment grounding conductor
• Grounding electrode conductor

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Grounded Conductor

• A current carrying conductor that is connected to
  the earth
• Often called the neutral wire
• Color must be white or natural gray
• Known as identified conductor
• Identity must be maintained throughout a circuit
  and the electrical system

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Grounded Conductor

• NEVER connected to a fuse, circuit breaker, or a
  switch
• One grounded conductor must be connected to all
  120 volt outlets or equipment

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UNGROUNDED CONDUCTOR

• A current carrying conductor that is not
  connected to the earth
• Often called the hot wire
• Color should not be white, gray, or green. Color
  may be black, red, blue, etc.
• Circuit breakers (or fuses) and switches are
  placed on the ungrounded conductor

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UNGROUNDED CONDUCTOR

• One ungrounded conductor must be connected to all
  120 volt outlets or equipment.
• Two ungrounded conductors must be connected to
  all 240 volt outlets or equipment.

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EQUIPMENT GROUNDING CONDUCTOR

• Under normal conditions, the equipment grounding
  conductor is never a current carrying conductor.
  It serves as a path to ground if a fault occurs
  in electrical equipment or the electrical system
• May be a bare wire or may have green or green
  with yellow stripe insulation

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EQUIPMENT GROUNDING CONDUCTOR

• Always connected to the grounding terminal of
  devices (receptacles, switches, etc.)
• Always connected to non-current carrying metal
  parts of equipment and circuits (including all
  metal boxes)

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GROUNDING ELECTRODE CONDUCTOR

• The large bare copper wire that connects the
  electrical system to the grounding electrode
• Size is determined by the size of service
  entrance cable being used

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COLOR CODING OF ELECTRICAL CONNECTIONS

• Silver or white colored terminal - attach the
  grounded conductor
• Copper or brass colored terminal -attach the
  ungrounded conductor
• Green colored terminal - attach the equipment
  grounding conductor