For residential wiring in
Connecting wire is the most mundane part of this project. On the other hand, if the wrong gauge wire is used or if it is improper;y joined to components,, bad things happen that compromise performance as well as safety. When wire carries current, the wire gets hot. the amount of heat generated varies with the square of the current. A convention known as the American Wire Gauge (AWG) standard was created by manufacturers of wire to put sanity in the market place. In AWG, #14 wire is rated to carry 15 A (Amperes) safely; #12 wire carries 20 A. (See the entire list at AWG web site in the box below.) Whether a circuit draws too much current depends on the action of a fuse or circuit breaker.
Breakers are installed permanently in a control panel and should be sized to protect the wire attached (say a 15 Amp breaker protecting #14 wire). The good news about breakers is that they can be reset after being tripped. the bad news is that they are fairly expensive. By contrast, fuses are cheap, less than fifty cents per unit. Do the math for cost effectiveness.Their downside is that they must be replaced after an overload, which means you should have spare fuses on hand. More importantly, because house fuses have the same sized socket base, it is possible to replace a spent 15 Amp fuse with a new 30 Amp fuse. This practice, more common than it should be, is an invitation to disaster.
A length of 14-2 cable
A length of 14-3 cable
SPECIAL NOTES - WIRE PREPARATION for
1. Use #14 wire (rated for 15 A) instead
of the stiffer #12
2. All wire connections have to occur in a receptacle box
3. Circuit starts with supply plug which is not energized until the end.
4. Wire should enter the bottom of the box.
5. At least 6" of wire should enter the box
6. Plastic outer shielding should be cut back so that none of it is in the box
7. no more than ¾" black & white insulation should be stripped from end of wire
8. form 180 degree loop with stripped wire and place on screw
9. do not use "quick connector slots" at back of receptacles
10. identify colors of screws-brass, white, green
11. protocol black wire /brass screw; white wire /white screw; ground wire /green screw
12. only black wires are attached to switches
13. multiple ground wires can be attached to one ground wire which is attached to green screw
14. you need to inspect wire connections; do not attach receptacles & switches to blue boxes
15. yellow wire nuts connect two wires; reds are for three wires