S1 Key Points

                                                                                                                page 1  / page 2  / page 3 /  Key 
     Key Points  ⊰   


This 2 wire or 14/2 wg NM-B romex
sheathed cable actually has 3 wires;
1 black, 1 white and 1 bare
     
Use 14 gauge wire and 15 amp rated switches on a 15 amp circuit breaker.
- Use 12 gauge wire and 20 amp rated switches on a 20 amp circuit breaker.
- Do not use 10 gauge wire for residential switches or receptacles. 
- LINE or POWER or FEED =  is energized wiring that feeds electrical current to the circuit. The LINE is both a hot (usually black) and neutral (usually white) conductor.
LOAD = Something that needs and uses power. A load can be; a light, a garbage disposal, a receptacle ... etc 
HOT = The energized conductor connected to the circuit breaker usually black, red or blue but sometimes white with black tape.
NEUTRAL= The white or gray conductor that carries electrical current returning from a LOAD and is grounded at the main panel only.
SWITCH LEG or "SWITCHED LOAD" is the wire that becomes hot only when the switch (and the load/light) is on.
- The switch is cut into the hot black wire in the LINE heading to the load not the white NEUTRAL wire. Switching the neutral wire leaves hot current at the load even though the load is off.
- Additional lights can be tapped into any part of the "SWITCH LEG". Either at the switch, the light or by a junction cut into any part of the SWITCH LEG wiring.
- Danger; with the "Light Fed Method" wires at the light can still be hot even if the light is switched off.
- The code now requires a neutral at the switch box because some specialty switches need a NEUTRAL. Specialty switches like; digital timers, remote controlled switches and motion sensing switches.
- Do not use a dimmer on a switched receptacle, it will damage items like widescreen TVs. 
- Fire hazard; Do not use dimmers on fluorescent lights or CFLs (compact fluorescent lights) Some fluorescent lamps are dimmable but they are more expensive and most likely not what you have. 
- The factory tab between the 2 hot terminals, on a receptacle, has to be removed when installing a 1/2 switched receptacle. 
- Sometimes in switch wiring, a white wire is used like a black hot instead of a white neutral. It is supposed to be identified by marking it with a black marker or black tape. 
- A 3way switch can be used as a single pole; use the common terminal and one traveler terminal and mount the switch so that when it is flipped up the light is on.
- Don't confuse automotive wiring colors with building wiring colors. In some American automobiles, red wires are HOT and black wires are NEUTRAL or grounded to the chassis . In American buildings black is HOT, white is NEUTRAL and green or a bare wire is grounded.

Question; Is the switch leg wire always hot?
   Answer; No. The switch leg wire is only hot when the switch is on. (and the circuit breaker of course) 
   In order to simplify these wiring diagrams, the bare copper ground wire that comes with 14/2 and 12/2 is not shown.
   Question; What does the ground wire connect to?
   Answer; Ground wires are connected together inside switch and light boxes. Ground wires are also connected to any metal parts that are NOT suppose to be electrified so that if they do, accidentally, become hot they will trip the circuit off. The blue boxes in the photo are plastic and the light fixture is fiberglass. Plastic and fiberglass do not conduct electricity so the ground wire is coiled up into the box and not used. If the box or fixture was metal, it would have a ground wire or a ground screw that would connect to your ground wire. The switch, in the photo, does have a green ground screw attached to the metal strap. By connecting the ground wire to this ground screw we prevent the strap and any metal switch plate touching the strap, from becoming hot.
   Question; Can I put the switch on the white neutral wire?
   Answer; No. Not in this  method. If you put the switch on the neutral wire everything would work properly, you could flip the switch on and off and the light would go on and off but there is a hazard; switching this white neutral wire would leave hot current in the wires at the light even though the light is off.



 page 1  / page 2  / page 3 /  Key 

No comments:

Post a Comment