Electrical Wiring Residential Unit 5 Switch Control Receptacle Bonding Conductor Identification Title Page

Conductor Identification For alternating-current circuits, The NEC® requires that the grounded (identified) conductor have an outer finish that is either continuous white or gray. The grounded conductor is also called the neutral conductor. An ungrounded (hot) conductor must have an outer finish that is a color other than green, white, natural gray, or gray with three continuous white stripes. Notes Unit 5

Grounded (Neutral) Conductor For residential wiring, the 120/240 volt electrical system is grounded by the electric utility at their transformer, and again by the electrician at the main service. Notes Unit 5

Grounded (Neutral) Conductor By definition a neutral conductor is: The conductor that carries only the unbalanced current from the other conductors, as in the case of a multi-wire circuit of three or more conductors. The conductor where the voltage from every other conductor to it is equal under normal operating conditions. By these definitions, the white conductor in a two-wire branch circuit is not truly a neutral conductor Notes Unit 5

Color Coding (Cable Wiring) The conductors in nonmetallic-sheathed cable (Romex) are color coded as follows. Two-wire: One black (“hot” Phase conductor) One white (grounded “identified” conductor) One bare (equipment grounding conductor) Notes Unit 5

Color Coding (Cable Wiring) Three-wire: One black (“hot” Phase conductor) One white (grounded “identified” conductor) One red (“hot” Phase conductor) One bare (equipment grounding conductor) Notes Unit 5

Color Coding (Cable Wiring) Notes Unit 5

Changing Colors When Conductors Are in a Raceway For cable wiring such as nonmetallic-sheathed cable or armored cable, 200.7(C)(1) and (2) permits the white conductor to be used for single-pole, three-way, or four-way switch loops. These code sections require that when used for a switch loop, the conductor that is white is to be used for the supply to the switch, and not as the return conductor from the switch, to the switched outlet. Notes Unit 5

Typical Colors for Residential Wiring Notes Unit 5

Push-in Terminations Screwless push-in terminals on receptacles are “listed” by Underwriters Laboratories (UL) for use only with solid 14 AWG copper conductors. Notes Unit 5

Push-in Terminations They are not to be used with: Aluminum or copper-clad aluminum conductors. Stranded conductors 12 AWG conductors By design, the holes are large enough to take only a 14 AWG solid conductor. Push-in terminals for 12 AWG solid copper conductors are still permitted on snap switches. Notes Unit 5

Exploded Receptacle Diagram Notes Unit 5

Always pigtail for more than 2 conductors Notes Unit 5

Receptacle Configurations 125V 15A 250V Notes 20A 125V 20A 250V Unit 5

Conductor Color Coding For Switch Connections Always connect a white wire to the white (silver) terminal or to the white wire of a lampholder or receptacle. Always connect the black switch-leg conductor (red in some cases) to the black wire (or dark brassy terminal) of a lampholder or receptacle. Notes Unit 5

Conductor Color Coding For Switch Connections In cables, always re-identify white conductors when they are used as ungrounded (hot) conductors. This re-identification must be done wherever the conductors are visible and accessible. Never use a green colored insulation for a grounded or ungrounded conductor. Green is reserved for equipment grounding conductors Notes Unit 5

Connecting Switches, Receptacles, and Lighting Outlets. A conductor carrying an alternating current produces a magnetic field (flux) around the conductor. The greater the current, the stronger the magnetic field. Notes Unit 5

Connecting Switches, Receptacles, and Lighting Outlets. In alternating current @ 60Hz., the current and magnetic field reverses direction 120 times each second. If the conductor is run through a steel raceway, steel jacketed cable, or a knockout in a steel box, the alternating magnetic field will induce heat into the steel. Notes Unit 5

Connecting Switches, Receptacles, and Lighting Outlets. When all the conductors of the same circuit are run through the same raceway, the magnetic fields around the conductors are equal and opposite, thereby canceling one another out. The NEC® 300.3(B) requires that “all conductors of the same circuit and, where used, the grounded conductor, all equipment grounding conductors and bonding conductors shall be contained within the same raceway, trench, cable, or cord, unless otherwise permitted” Notes Unit 5

Connecting Switches, Receptacles, and Lighting Outlets. NEC® 404.2(A) requires that “three-way and four-way switches shall be so wired that all switching is done only in the ungrounded circuit conductor”. Switch loops do not require a grounded conductor. Notes Unit 5

Proper Use of Conductors in Romex Cabling Notes Unit 5

Conductors in Trenches Notes Unit 5

Grounded Conductors at Switch Locations Are grounded (neutral) conductors needed at switching locations? In most cases, the answer is no. However, a grounded conductor is required when a true pilot light is connected at the switch location. In the event that electronic dimming and/or switching devices are to be used, a neutral may be required at one or more of the switch locations. Notes Unit 5

Grounded Conductors at Switch Locations Notes Unit 5

Using a 2-Wire as a Switch Loop Notes Unit 5

Using a 3-Wire To Send a Feed Through a Light Notes Unit 5

3-Way Switch Line Diagram and Graphic Notes Unit 5

3-Way Fed at Light, Dead Ended at Both Ends Notes Unit 5

4-Way Switch Line Diagram & Drawing Notes Unit 5

Bonding and Grounding at Receptacles and Switches A metal box is considered to be adequately grounded when the wiring method is armored cable, non-metallic sheathed cable with ground, or a metal raceway such as EMT. Grounding and bonding of the equipment grounding conductor to a metal box, switch, or receptacle is important. Most metal boxes have a No. 10-32 tapped hole for securing a green hexagon shaped equipment grounding screw. Notes Unit 5

Bonding and Grounding at Receptacles and Switches To ensure the continuity of the equipment grounding conductor path, 250.148 requires that where more than one equipment grounding conductor enters a box, they shall be spliced with devices “suitable for the use.” Splices shall not depend on solder! In existing locations where there is no equipment grounding conductor in a switch box, and where within reach of a conductive floor (i.e. concrete, tile, etc), use non-metallic faceplates. Notes Unit 5

Bonding and Grounding at Receptacles and Switches Notes Unit 5

Bonding and Grounding at Receptacles and Switches Notes Unit 5

Various Listed Means of Grounding and Bonding Notes Unit 5

A “G-Clip” is a Great Way to Attach a Ground To an Existing Metal Box Notes Unit 5

Timers Timers a unique on that they provide automatic control of electrical loads. Timers are used where a load is to be controlled for specific “ON/OFF” times of the day or night. Timers come in a wide variety of styles. Some fit in switch-boxes, some have weatherproof cases. Timers can also be used with photocells to provide even more flexibility for exterior lighting. Notes Unit 5

Intermatic Timer Notes Unit 5

Photocells Notes Unit 5

This Concludes Unit #5 Notes Unit 5