• In contemporary wiring, individual wires run in a sheathed cable. "Two-wire with ground" and "three-wire with ground" cables are available:
  
   
  • Two-wire with ground cables have a black wire, a white wire and an uninsulated ground.
    
     
  • Three-wire with ground cables (used when installing three-way and four-way switches) have a black wire, a white wire, a red wire and an uninsulated ground.
    
     
• Older houses may have two-wire system called "knob and tube" wiring. With this system, individual wires are insulated with white or black treated fabric.

• The white wire is usually the neutral wire, but sometimes wiring installation requires it to be a hot wire. If the white wire is the hot wire, code it black with paint or electrical tape. A previous installer may not have coded the wire so be careful. If a red wire is present, it should also be hot.
  
   
• The black wire is "hot."
  
   
• The exposed copper wires are ground wires.

• If a single cable enters the box (or one set of black and white wires), the fixture is at the end of the circuit. This is usually, but not always, the situation with ceiling light fixtures.
  
   
• If two cables enter the box (or two sets of black and white wires in older "knob and tube" installations), the fixture is in the middle of a circuit.
  
   
• A third cable (or set of black and white wires) may also enter the fixture, depending upon the installation. The placement of the fixture within the circuit affects how it is wired.

Replacing Existing Light Fixtures

• Do this at the service panel (breaker box), and check the circuit to make sure it is off.
  
   
• Inexpensive circuit testers are available. The testers are essentially a light with two probes designed to handle house current. They are useful for testing ground and hot wires, and for determining whether a light fixture is carrying current.
  
   
• A non-contact voltage detector is available which can detect between 100 and 600 volts AC without actually having to touch a wire.

• The majority of the time when replacing light fixtures you simply connect white wires to white wires and black wires to black wires.
  
   
• If several wires are involved, however, or if the wiring seems more complicated and perhaps even includes a red wire, take note of the connections before you disconnect them.
  
   
• Make yourself a sketch of how the fixture is wired (index the sketch by wire color) or mark the wires themselves with masking tape and a pencil so you will know how to put them back.

Good idea: The physical installation of your new fixture depends upon the fixture itself, so refer to the manufacturer's instructions for directions on this part of the process.

1. Now that you know how the existing wiring looks, remove the old fixture.
   
    
2. Make your electrical connections by "tying in" to the home wiring using plastic connectors, often called "wire nuts." Install the connector by twisting it onto the wires.
   
    
3. If the chandelier includes a ground wire (bare or green insulated wire), connect it to any other ground wires and grounding screws already in place in the metal electrical box used to support the chandelier.
   
    
4. Finish installing the chandelier as indicated in your manufacturer's instructions.

• Either the breaker will trip when you turn on the light switch
  
   
• Or it simply won't work
  
   

• If the breaker has indeed tripped, look again at your sketch or your masking tape tags to see where the wrong connection was made.
  
   
• Double-check your wire connections to see that the wires are properly connected and insulated by the wire nuts.