Chapter Six Ground-Fault Circuit Interrupters, Arc-Fault Circuit Interrupters, Surge Protective Devices, Immersion Detection Circuit Interrupters, and Appliance Leakage Current Interrupters

Objectives After studying this chapter, you should be able to: Understand how GFCIs, AFCIs, IDCIs, and ALCIs operate Understand NEC® requirements of where and how GFCIs and AFCIs are to be installed and connected Understand why AFCIs and GFCIs should not be used on a shared neutral branch circuit unless it is listed as such

Objectives (cont’d.) Select and install other special purpose devices including tamper-resistant and weather-resistant receptacles Understand the important NEC® requirements for replacing existing receptacles Know the rules for providing GFCI protection on construction sites Understand the basics of surge protective devices

Electrical Shock Hazards There can be no compromise where human life is involved! If equipment is not properly grounded, the potential for an electrical shock is present The shock hazard exists whenever the user can touch both the defective equipment and grounded surfaces

Electric Shock Hazards (cont’d.) Electrical shock can cause internal damage The effect of current passing through the body depends on: Circuit characteristics Body resistance Contact duration Path Humidity

Electric Shock Hazards (cont’d.) The resistance (ohms) of the human body varies from a few hundred ohms to many thousand ohms Generally, voltages less than 50 volts are safe Voltages 50 volts and greater are considered lethal

FIGURE 6-1 The time/current curve shows the tripping characteristics of a typical Class A GFCI. Note that if you follow the 6-mA line vertically to the crosshatched typical time/current curve, you will find that the GFCI will open in from approximately 0.035 second to just less than 0.1 second. One electrical cycle is 1/60 of a second (0.0167 second). An air bag in an automobile inflates in approximately 1/20 of a second (0.05 second). © Cengage Learning 2015 14

Electric Shock Hazards (cont’d.) AC systems from 50 to 1000 volts are required to be grounded A grounded system enhances safety

Code Requirements for Ground-Fault Circuit Interrupters (210.8) There are many receptacle locations that are required to be GFCI protected Receptacles located near water must be GFCI protected

FIGURE 6-5 Ground-fault circuit interrupter as part of the feeder supplying a panel that serves a number of 15- and 20-ampere branch circuits. This is permitted by NEC® 215.9 but is rarely—if ever—used in residential wiring. © Cengage Learning 2015 14

Ground-Fault Circuit Interrupters in Residence Circuits GFCI protection is not required for a receptacle for a fire alarm or burglar alarm system GFCI breakers protect the entire circuit

Feed-Through Ground-Fault Circuit Interrupter Most GFCI receptacles on the market today have the “feed-through” feature GFCI receptacles can be wired to protect “downstream” receptacles All GFCI receptacles have a manual TEST button and a RESET button

Testing and Recording of Test Data for GFCI Receptacles GFCIs should be tested often Particularly in high lightning strike areas Self-testing GRCIs are available UL requires detailed installation and testing instructions in GFCI packaging

Arc-Fault Circuit Interrupters (AFCIs) AFCI devices are relatively new There are circuit-breaker and receptacle type AFCIs AFCI and GFCI protect against different types of electrical hazards

Testing and Recording of Test Data for GFCI Receptacles (cont’d.) AFCI protection is required in dwelling unit Kitchens Family rooms Dining rooms Living rooms Parlors Libraries Dens Bedrooms Sun rooms Recreation rooms Closets Hallways Laundry areas Similar rooms or areas

Other Special Purpose Receptacles Tamper-resistant receptacles A major step to reduce the number of injuries Small children especially insert “things” into slots Weather resistant: installed in damp locations

Replacing Existing Receptacles NEC is very specific on the type of receptacle permitted to be used for replacements Code rules are found in 406.4(D) Replacing existing two-wire receptacles Where grounding means exists Where grounding means does not exist

FIGURE 6-22 Where a grounding means does not exist, there are certain marking requirements as presented in this diagram. Do not connect an equipment grounding conductor between these receptacles; see 406.3(D)(2). © Cengage Learning 2015 14

Personnel Ground-Fault Protection for All Temporary Wiring Because of the nature of construction sites, there is a continual presence of shock hazard Most electricians and other construction site workers carry their own listed portable ground-fault circuit-interrupter cord sets

IDCIs and ALCIs The large attachment plug cap on hand-held grooming appliances such as hair dryers, combs, and curlers is an IDCI or ALCI If the appliance is dropped into water or gets wet, the IDCI or ALCI will safely de-energize the appliance

FIGURE 6-26 An example of a temporary construction site combination meter, breakers, and receptacles. The breakers and receptacles are under the lift-up cover. © Cengage Learning 2015 18

Surge Protective Devices (SPD) Code requirements found in Article 285 Ring wave: originate within the building and can be caused by such things as copiers, computers, and printers Impulse: these transients originate outside of the building and are caused by utility company switching, lightning, and so on