1. The items at right are called DUPLEX RECEPTACLES. They make 120V AC, which is otherwise lethal, safely available  A receptacle has five screws.  The top picture shows two white (plain metallic) screws at center and a single ground  screw (usually green) at right.  The middle picture shows two brass (yellow metallic) screws.  The rules for connecting wires to this unit are straightforward:  black to brass, white  to white, ground to green.  It is alliteration; your English instructor will be so pleased.
  2. Sometimes, it is not immediately evident which screws are yellow metallic.  A glance at the bottom picture shows two slots,  one being wider than the other.  The wiring rule is white to wide, more alliteration.  More happiness.
  3. The screws in each pair of  screws are connected by a metal tab so that when one screw os energized, so is the other..  Thus, an unused pair of screws  become  useful as a power  source.
  4. On the reverse side of each  unit are four small holes slightly larger than the diameter of the stripped connecting wire.  Upon insertion into the hole, the wire is held secure by a small spring

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last edited 12/22/05