Principles & Applications Residential Wiring Concepts Electricity Principles & Applications Sixth Edition Richard J. Fowler Chapter 16 Residential Wiring Concepts ©2003 Glencoe/McGraw-Hill

INTRODUCTION Equipment-grounding Conductor Ground-Fault Circuit Interrupter Arc-Fault Circuit Interrupter Three-Way Lighting Circuit Four-Way Lighting Circuit Lighted-Handle Switches Low-Voltage Control Circuit

Facts about Residential Wiring A residence uses a 120-V/240-V single-phase system. Hot conductors are 120 V with respect to neutral. Hot conductors are 240 V with respect to each other. Neutral conductors are either white or neutral gray.

More Facts About Residential Wiring White conductors may be used as hot conductors. An AFCI reduces the risk of electrical fires. A GFCI protects people from ground-fault currents. Equipment-grounding conductors are never fused.

Equipment-Grounding Conductor Short 7.0 A 0.0 A Ungrounded table Grounded floor Motor standard receptacle 7.5 A 0.5 A There is no circuit fault. The motor is operating normally. The motor develops a partial short. The branch circuit breaker doesn’t trip. The motor continues to operate with some ground-fault current. No shock is received because the motor frame is grounded.

Equipment-Grounding Conductor ?.? A Motor Short standard receptacle 7.5 A 7.0 A Ungrounded table Grounded floor 0.5A 7.0 A The partially shorted motor continues to run. It doesn’t trip the branch circuit breaker. Then the equipment-grounding conductor develops a broken or corroded connection. A severe, or fatal, shock is received because the motor frame is not grounded.

Ground-Fault-Circuit Interrupter Short Motor GFCI receptacle 7.0 A 0.0 A Ungrounded table Grounded floor 0.0 A 0.0 A A faulty equipment-grounding conductor doesn’t trip the GFCI. With no ground, a partial short in the motor doesn’t trip the GFCI either. No severe shock is received because the GFCI trips at about 5 mA.

Arc-Fault-Circuit-Interrupter Circuit Breaker Loose screw OFF ON Hot bus Neutral bus This circuit breaker will open when an arc occurs. Click the mouse to try it.

Ground-Fault Quiz Is an equipment-grounding conductor ever fused or switched? No Is a green conductor ever used for a neutral conductor? No Can a neutral-gray conductor be used for a neutral conductor? Yes Will a ground-fault current greater than 10 mA trip a circuit breaker? No Will a ground-fault current greater than 10 mA trip a GFCI? Yes Will a load current of 25 A trip a GFCI receptacle rated at 20 A? No Will a 10-A ground-fault current cause an AFCI circuit breaker to trip? No

Wiring a Three-Way Lighting Circuit fixture 14-3/G 14-2/G Connect a hot conductor to the pole (dark-colored screw). Ground the metal box. Connect the throws together. Continue the neutral and equipment-grounding conductors. Connect a hot conductor to the remaining pole. Again continue the neutral and equipment-grounding conductors. Finally, connect the light fixture to the appropriate conductors.

A Four-Way Lighting Circuit The circuit is in the off position. Equipment grounding is not shown. Flipping the 4-way switch turns the circuit on. Flipping either 3-way switch turns the light back off. Flipping the 4-way switch again turns the circuit back on. Flipping the other 3-way switch turns the circuit off again. In summary, flipping any switch at any time will reverse the condition of the circuit.

Lighted-Handle Switch 120-V lamp When the light is off (switch open), the switch handle is lit. When the light is on (switch closed), the switch handle is not lit.

Lighted-Handle 3-Way Switches B1 B2 H R1 R2 N The light is on and the handles are not lit. When either switch is toggled, the light goes out and both handles are lit.

Low-Voltage-Controlled Light Circuit supply Click the mouse and watch. A switch is rocked to off. The relay opens. The light goes out. And, the switch returns to its open position. Another switch is rocked to off. Nothing happens. Again, the switch returns to its open position. Now, a switch is rocked on. The relay closes. The light goes on. Again, the switch returns to its open position.

Switching-Circuit Quiz A 3-way lighting circuit requires _____ insulated conductors between switches. three A 4-way lighting circuit requires _____ insulated conductors between switches. three A _____ colored conductor should not be used in the return leg of a switch. white A 4-way lighting circuit provides control of a light from _____ locations. three The handle of a lighted-handle 3-way switch is lit when the light is _____ . off A three-terminal relay stays in the on position until the _____ is pulsed. off coil

REVIEW Equipment-Grounding Conductor Ground-Fault Circuit Interrupter Arc-Fault Circuit Interrupter Three-Way Lighting Circuit Four-Way Lighting Circuit Lighted-Handle Switches Low-Voltage Control Circuit