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Introduction Once the facilities maintenance technician has a good understanding of basic electrical theory and electrical safety, the technician can attempt to trouble shoot, repair, and install basic electrical circuits and appliances. The previous section introduced the technician to basic electrical theory. This section introduces the concepts of safety and the basic procedures for troubleshooting and repairing basic electrical circuits and devices (switches, receptacles, and so on). Practical Electrical Theory Before a technician can safely work with an electrical system, he or she should have a good understanding of the basic principles of electrical theory. A direct relationship exists among voltage, current, and resistance. Power is the product of voltage and current. Voltage is the amount of electrical pressure in a given circuit and is measured in volts. Current (or amperage) is the flow of electrons through a given circuit and is measured in amps. Resistance is the opposition to current flow in a given electrical circuit and is measured in ohms. Power is the electrical work that is done in a given circuit and is measured in wattage (watts) for a purely resistive circuit and volt-amps (VA) for an inductive/ capacitive circuit. -- A sine wave displayed on an oscilloscope SINE WAVE 270° 360° 90° 180° AC vs. DC Two types of electrical current are used to power electrical circuits today: alternating current (AC) and direct current (DC). AC is electrical current whose magnitude and direction vary cyclically, whereas that of DC does not modulate and therefore remains constant. AC is primarily used in residential, commercial, and industrial applications as the primary source of power. DC is used primarily in electronic, low-voltage applications, batteries, and so on.
Sine Waves AC continually reverses direction. An oscilloscope is an instrument that measures the amount of voltage over a period of time and can display this voltage, called a waveform, on a screen. Many types of waveforms exist, but we will discuss the one most refrigeration and air-conditioning technicians are involved with, the sine wave. The sine wave displays the voltage of one cycle through 360°. In the United States and Canada , the standard voltage in most locations is produced with a frequency of 60 cycles per second. Frequency is measured in hertz (Hz). Therefore, the standard frequency in the United States and Canada is 60 Hz. --is a sine wave as it would be displayed on an oscilloscope. At the 90° point the voltage reaches its peak (positive); at 180° it’s back to 0; at 270° it reaches its negative peak; and at 360° it’s back to 0. If the frequency is 60 Hz, this cycle would be repeated 60 times every second. The sine wave is a representation of a trigonometric function of an AC cycle. --shows the peak and peak-to-peak values. As the sine wave indicates, the voltage is at its peak value briefly during the cycle. Therefore, the peaks of the peak-to-peak values are not the effective voltage values. The effective voltage is the root-mean square (RMS) voltage. This is the AC value measured by most voltmeters and ammeters. The RMS voltage is 0.707 3 the peak voltage. If the peak voltage were 170 volt, the effective voltage measured by a voltmeter would be 120 V (170 V 3 0.707 5 120.19 V). Sine waves can illustrate a cycle of an AC electrical circuit that contains only a pure resistance, such as a circuit with electrical heaters. In such a pure resistive circuit, the voltage and current will be in phase. This is illustrated with sine waves. Notice that the voltage and current reach their negative and positive peaks at the same time. Sine waves can also illustrate a cycle of an AC electrical circuit that contains a fan relay coil, which will produce an inductive reactance. The sine wave will show the current lagging the voltage in this circuit. A sine wave illustrating a cycle of an AC electrical circuit that has a capacitor producing a pure capacitive circuit. In this case the current leads the voltage. -- Peak and peak-to-peak AC voltage values: PEAK-TO-PEAK; PEAK; PEAK -- This sine wave represents both the voltage and the current in phase in a resistive circuit -- The RMS or effective voltage Single-Phase AC vs. Three-Phase AC Single-phase AC is the most commonly used electrical supply for single-family and multifamily dwellings. Single phase consists of two ungrounded conductors (hot wires) and one grounded conductor (neutral wire). When measuring voltage between the two hot wires of this type of system, you will read approximately 240 volts. If you read from any one hot wire to the neutral, you should read approximately 120 volts. Make sure that the meter that you are using to test voltage is rated appropriately. Three-phase AC is most often used for commercial buildings, healthcare facilities, and industrial facilities. There are always three ungrounded conductors (hot wires) in this type of system. The three-phase system may or may not have a neutral wire. The common voltage levels for the three-phase system will be 208, 230, 240, 480, 575, or 600 when measured between the two hot wires. This is referred to as the line voltage. If a neutral is present, then voltage read from any one hot wire to the neutral wire will equal the line voltage divided by the square root of 3 (1.732). -- This sine wave represents the current lagging the voltage (out of phase) in an inductive circuit -- This sine wave represents a capacitive AC cycle with the voltage lagging the current. The voltage and current are out of phase Safety, Tools, and Test Equipment One of the most import aspects of any assigned task is to perform the assignment in a safe manner. This includes using tools and equipment that are properly maintained and designed for that particular task. Safety Many safety considerations must be adhered to while working on electrical systems, equipment, and devices. Many of the safety procedures are outlined in the OSHA standard (29 CFR Part 1926) and must be followed while working on electrical systems, equipment, and devices. In any installation, repair, or removal of electrical equipment or devices, use the proper wiring methods and practices stipulated in the National Electrical Code, better known as the NEC (NFPA 70). The NEC is written to ensure the protection of people and property from the hazards that arise from installation and/or repair of electrical systems or equipment. One must also follow all local codes and regulations that might exceed the minimum standards required by the NEC. Prior to beginning any work on electrical systems, equipment, or devices, always consult with the local authority having jurisdiction (building/electrical inspector) on the local codes and regulations that might affect the proper and safe installation of electrical systems, equipment, and devices in your area. The OSHA and NEC safety articles mandate that only qualified personnel should work on electrical systems, equipment, or devices. This is to protect not only the property owner but also the person performing the installation. A qualified person is one who has the skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training on the hazards involved. Lock-out/tag-out procedures, as stated in the OSHA standard 1926.417 and the NFPA 70E standard, should be followed at all times to prevent electrical shock or even death by electrocution. Various forms of lockouts exist, which can be placed on safety disconnects, switches, and breakers. You must use the lockout that will prevent current from flowing through the circuit that you are working on. -- shows some examples of the different lockouts that are available. The NFPA 70E mandates that qualified personnel should never work on any part of an energized electrical system that is over 50 volts AC without the proper arc l ash/ arc blast personnel protective clothing (PPE) and without using 1,000-volt-rated tools. This mandate is in effect for your protection only. Also, safety glasses should be worn at all times while working on electrical systems, equipment, or devices. Working Space around Electrical Equipment Adequate lighting and space is required around electrical equipment so that maintenance on the electrical equipment can be performed safely. The NEC 110.26 covers the minimum working space, access, headroom, and lighting requirements for electrical equipment such as switchboards, panelboards, and motor control centers operating at 600 volts or less. Tools and Test Equipment Always ensure that all hand tools and power tools are inspected before and after use. Look for any defects or damage that may cause injury while the hand tool or power tool is in use. If you notice any damage, the tool should not be used until it has been repaired by a qualified person (someone trained to work on the damaged tool). If a qualified person is not available to repair the damaged tool, the tool should be either discarded or put away until such a time when a qualified person can repair it. Regularly maintain and clean all hand tools and power tools to ensure their proper operation. Always use calibrated test equipment when testing electrical systems, equipment, or devices to ensure accurate measurements. Never use test equipment on any energized circuit above what it’s rated for. This could cause the test equipment to explode, possibly leading to serious injury or even death. -- Examples of lock-out/tag-out devices Volt-Ohm-Milliammeter A Volt-Ohm-Milliammeter (VOM), often referred to as a multimeter, is an electrical instrument that measures voltage (volts), resistance (ohms), and current (milliamperes). This instrument has several ranges in each mode. It’s available in many types, ranges, and quality, either with a regular dial (analog) or with a digital readout. A typical multimeter with a digital readout. If you purchase one, be sure to select one with the features and ranges used by technicians in this field. The voltmeter that you use is very important. Your life may depend on knowing what voltages you are working with. Be sure to get the best one you can afford. Inexpensive ones are tempting. See procedure for "Using a Voltage Tester" and "Using a Noncontact Voltage Tester." AC Clamp-On Ammeter An AC clamp-on ammeter is a versatile instrument, which is also called clip-on, tang-type, snap-on, or other names. Some can also measure voltage or resistance or both. Unless you have an ammeter like this, you must interrupt the circuit to place the ammeter in the circuit. With this instrument you simply clamp the jaws around a single conductor.-- See procedure for "Using a Clamp-On Ammeter." Megohmmeter A megohmmeter is used for measuring very high resistances. This particular device can measure up to 4,000 megohms. Wiring and Crimping Tools Wiring and crimping tools are available in many designs. A combination tool for crimping solderless connectors, stripping wire, cutting wire, and cut ting small bolts. This also illustrates an automatic wire stripper. To use this tool, insert the wire into the proper strip-die hole. The length of the strip is determined by the amount of wire extending beyond the die away from the tool. Hold the wire in one hand and squeeze the handles with the other. Release the handles and remove the stripped wire. -- A typical VOM with digital readout. (Fluke Corporation) -- Measuring amperage by clamping the meter around the conductor. Electrical Conductors When working with electricity, the facilities maintenance technician will be exposed to various conductors (wire, cables, etc.). Having a good understanding of different types of conductors (wires) used in an electrical circuit is essential when working with electricity. Using the wrong size or type of conductor can result in a loss of property and/or even a fatality. -- Analog ohmmeter: RESISTOR WITH A RESISTANCE VALUE OF 10 OHMS; OHMMETER SELECTOR SWITCH IS ON R x 1 and THE NEEDLE IS POINTING TO 10 OHMS. MULTIPLY: THE 10 OHMS BY 1 TO GET THE ACTUAL VALUE BEING READ. -- Wire stripping and crimping tool Wire Sizes All conductors have some resistance. The resistance depends on the material, the cross-sectional area, and the length of the conductor. A conductor with low resistance carries a current more easily than that with high resistance. The proper wire (conductor) size must always be used. The size of a wire is deter mined by its diameter or cross section. A larger-diameter wire has more current-carrying capacity than a smaller-diameter wire. Standard copper wire sizes are identified by American Standard Wire Gauge numbers and measured in circular mils. A circular mil is the area of a circle 1/1,000 in. in diameter. Temperature is also considered because resistance increases as temperature increases. Increasing wire size numbers indicate smaller wire diameters and greater resistance. For example, number 12 wire size is smaller than number 10 wire size and has less current-carrying capacity. The technician should not determine and install a conductor of a particular size unless licensed to do so. The technician should, however, be able to recognize an undersized conductor and bring it to the attention of a qualified person. As mentioned previously, an undersized wire may cause voltage to drop, breakers or fuses to trip, and conductors to overheat. The conductors are sized by their amperage-carrying capacity, which is also called ampacity. -- contains a small part of a chart from the NEC and a partial footnote for one type of conductor. This chart as shown and the footnote should not be used when deter mining a wire size. It’s shown here only to familiarize you with the way in which it’s presented in the NEC. The footnote actually reduces the amount of amperes for number 12 and number 14 wires listed in the NEC table in --. The reason is that number 12 and number 14 wires are used in residential houses where circuits are often overloaded unintentionally by the homeowner. The footnote exception simply adds more protection. An example of a procedure that might be used for calculating the wire size for the outdoor unit for a heat pump follows. This outdoor unit is a 3½-ton unit (42 amp means 42,000 Btu/hour or 3½ tons). The electrical data show that the unit compressor uses 19.2 full-load amperage ( FLA ), and the fan motor uses 1.4 FLA for a total of 20.6 FLA. The specifications round this up to an ampacity of 25. In other words, the conductor must be sized for 25 amperes. According to the NEC, the wire size would be 10. The specifications for the unit indicate that a maximum fuse or breaker size would be 40 amp. This will give the compressor some extra amperage for the locked-rotor amperage (LRA) at start-up. Some manufacturers specify the ampacity and the recommended wire size in the directions printed on the unit nameplate. When you find a unit that has low voltage while operating, you should first check the voltage at the entrance panel to the building. If the voltage is correct there and low at the unit, either there is a loose connection, there is undersized wire, or the wire run is too long. -- This section of the NEC shows an example of how a wire is sized for only one type of conductor. It’s not the complete and official position but is a representative example. -- The cross section of a wire: DIAMETER OR CROSS SECTION OF WIR; If a wire is too small for the current passing through, it will overheat and possibly burn the insulation and could cause a fire. NM Cable Using improper wire types and wire sizes can result in a fire! It’s important to know what type of wire or cable is used for a given application. The most common type of cable used in single-family and multifamily dwellings is NM cable (commonly referred to as Romex). NM cable is covered in Article 334 of the NEC, where you will find its proper use and installation methods. NM cable is available in many sizes and conductor pairs. This means that an NM cable comes with two, three, or four current-carrying conductors and a ground. The ground that is present in NM cable is typically bare (without insulation); all of the current-carrying conductors will have an insulation covering that is identified by the following colors: Black, Red, Blue, White The blue insulated conductor is found only in four-conductor NM cable. Admittedly, a four-conductor NM cable with ground is rarely used or seen, but it does exist. Most often, NM cable is sold as a two conductor with ground or a three conductor with ground. -- This specification sheet for one unit shows the electrical data that are used to size the wire to the unit. (Trane) Electrical Devices, Fixtures, and Equipment Typically the electrical repair that a facilities maintenance technician does will consist of troubleshooting, repairing, and/or replacing electrical devices, fixtures, and equipment as opposed to replacing conductors. When troubleshooting, repairing, and/or replacing electrical devices, fixtures, and equipment, always follow manufacturer's recommendations, warning, and specifications. In most cases manufacturers of electrical devices (outlet, switch, a light fixture, etc.) supply diagrams on how to wire the device with the device. Boxes A multitude of boxes are used today for electrical installations. Only the most common of these boxes will be discussed here. One of the most common boxes in use is the single gang nail-up box. It’s made of plastic or fiberglass and is typically used during new construction before the drywall is installed. This box will have enough room for only one yoked device, such as a switch, a receptacle, or a dimmer switch. A two-gang nail-up box will have enough room for two yoked devices and a three-gang nail-up box for three yoked devices. The "cut-in" box is made of plastic or fiberglass and is used when a device must be installed after the drywall is already in place. See procedure for "Installing Old-Work Electrical Boxes in a Sheetrock Wall or Ceiling." Round ceiling boxes are available in various diameters, depths, and shapes. Four common types of ceiling boxes are: Pancake (the shallow box) 4" round nail-up box 4" round cut-in box Fan-rated ceiling box Ceiling fan boxes are used to support a lighting fixture in the ceiling. It’s important to know that a ceiling fan should not be installed on a ceiling box that is not fan-rated. If a ceiling box is rated to support a fan, it will be clearly and legibly stamped into the interior of the box. If a fan is mounted to a box that is not rated for a ceiling fan, the fan could fall during operation and cause injury to someone underneath it. -- Gang devices -- Cut-in box -- Round ceiling box -- Ceiling fan box -- Weatherproof box and box with cover Weatherproof boxes are used whenever a device (receptacle or switch) is installed in a wet location. This box is designed to keep the elements of the weather from affecting the electrical circuit and device that is contained within the box. If this box is installed in the direct weather and it houses a receptacle, it’s to have an "in-use" cover. An in-use cover looks like a giant clear bubble. Feeder Circuits A feeder is the circuit conductor between the service equipment and the final branch circuit overcurrent protection device. Some commercial wiring situations may call for another load center (panel), which is called a subpanel, to be located in another part of the structure. The reason for installing a subpanel is usually to locate a load center closer to an area of the house where several circuits are required. It’s the wiring from the main panel to the subpanel that is referred to as the feeder. The feeder typically constitutes wiring in a cable or individual wires in an electrical conduit that are large enough to feed the electrical requirements of the subpanel they are servicing. Surface Metal Raceways When it’s impossible to conceal conductors (For example, around a desk, counter, cabinets) a raceway is often used. Surface raceways, which are governed by Articles 386 and 388 of the NEC, are typically made of either metal or nonmetallic materials. It should be noted that the number of conductors in a raceway is limited to the design of the raceway. Also that the combined size of the conductors, splices, and tape should not exceed 75 percent of the raceway. Also all conductors that are to be installed in a raceway should be spliced either in a junction box or within the raceway. Multi-outlet Assemblies The NEC defines a multi-outlet assembly as a surface, flush, or freestanding raceway designed to hold conductors and receptacles, assembled in the field or at the factory. They offer a high degree of flexibility to an installation by allowing for the likelihood that the installation and use requirements could change. For example, in an office building where cubicles are utilized, multi-outlet assemblies offer a suitable solution. They are also utilized in heavy-use situations, For example, computer rooms and laboratories. Floor Outlets Floor outlets are often used in large office complexes where desks will be positioned too far away from a wall to effectively run a power cord. Floor outlets can be contained within a under floor raceway or by installing floor boxes. It should be noted that the installation requirements for an under floor raceway are set forth in the NEC Article 390. Panelboards A panelboard is defined by the NEC as a single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed on or against a wall, partition, or other support; and accessible only from the front. When separate feeders are to be run from the main service equipment to each of the areas of the commercial building, each feeder will terminate in a panelboard, which is to be installed in the area to be served. Circuit Protection Devices Circuit protection is essential to prevent the conductors in the circuit from being overloaded. If one of the power-consuming devices were to cause an overload due to a short circuit within its coil, the circuit protector would stop the current flow before the conductor becomes hot and overloaded. A circuit consists of a power sup ply, the conductor, and the power-consuming device. The conductor must be sized large enough that it does not operate beyond its rated temperature, typically 140°F (60°C) while in an ambient temperature of 86°F (30°C). For example, a circuit may be designed to carry a load of 20 amp. As long as the circuit is carrying up to its amperage, overheating is not a potential hazard. If the amperage in the circuit is gradually increased, the conductor will become hot. Proper understanding of circuit protection is a lengthy process. More details can be obtained from the NEC and further study of electricity. Fuses A fuse is a simple device used to protect circuits from overloading and overheating. Most fuses contain a strip of metal that has a higher resistance than the conductors in the circuit. This strip also has a relatively low melting point. Because of its higher resistance, it will heat up faster than the conductor. When the current exceeds the rating on the fuse, the strip melts and opens the circuit. -- (A) A circuit breaker. (B) A cutaway. (Schneider Electric) Plug Fuses Plug fuses have either an Edison base or a type S base (A). Edison-base fuses are used in older installations and can be used only for replacement. Type S fuses can be used only in a type S fuse holder specifically designed for the fuse; otherwise an adapter must be used (B). Each adapter is designed for a specific ampere rating, and these fuses cannot be interchanged. The amperage rating determines the size of the adapter. Plug fuses are rated up to 125 volt and 30 amp. -- (A) A type S base plug fuse. (B) A type S fuse adapter Electrical circuits must be protected from current over loads. If too much current flows through the circuit, the wires and components will overheat, resulting in damage and possible fire. Circuits are normally protected with fuses or circuit breakers. Dual-Element Plug Fuses Many circuits have electric motors as the load or part of the load. Motors draw more cur rent when starting and can cause a plain (single element) fuse to burn out or open the circuit. Dual-element fuses are frequently used in this situation. One element in the fuse will melt when there is a large overload such as a short circuit. The other element will melt and open the circuit when there is a smaller current overload lasting more than a few seconds. This allows for the larger starting current of an electric motor. Cartridge Fuses For 230-volt to 600-volt service up to 60 amp, the ferrule cartridge fuse is used (A). From 60 amp to 600 amp, knife-blade cartridge fuses can be used (B). A cartridge fuse is sized according to its ampere rating to prevent a fuse with an inadequate rating from being used. Many cartridge fuses have an arc-quenching material around the element to prevent damage from arcing in severe short-circuit situations . -- A dual-element plug fuse. (Cooper Bussmann) -- (A) A ferrule-type cartridge fuse. (B) A knife-blade cartridge -- A knife-blade cartridge fuse with arc quenching: ARC-QUENCHING; MATERIAL; FUSIBLE LINK Circuit Breakers A circuit breaker can function as a switch as well as a means for opening a circuit when a current overload occurs. Most modern installations in houses and many commercial and industrial installations use circuit breakers rather than fuses for circuit protection. Circuit breakers use two methods to protect the circuit. One is a bimetal strip that heats up with a current overload and trips the breaker, opening the circuit. The other is a magnetic coil that causes the breaker to trip and open the circuit when there is a short circuit or other excessive current overload in a short time. -- Single-pole circuit breaker (left). Double-pole circuit breaker right) -- Uninterruptible power supply (UPS) Emergency Backup Systems Emergency backup systems are designed to keep critical parts of an electrical system energized in the event of power loss. Hospitals and assisted living facilities have emergency backup systems in order that life support systems won’t be interrupted during the loss of power. These types of emergency backup systems will typically use a diesel engine that drives a generator. The facility will switch over to the generator only in the event of power loss. Another form of an emergency backup system is the uninterruptible power supply (UPS). This system uses a battery or batteries to supply constant power to the circuits connected to it in the event of power loss. This system is available in various sizes. A UPS can be small enough to fit on a desk, or it can be so large that it may require its own room or even its own building on the facility grounds. The larger UPS systems require a lot of maintenance to maintain the reliability of the batteries. Many safety issues have to be considered when working on or around these large battery backup systems, and it’s for this reason that only qualified personnel work on these systems. Electrical Switches and Receptacles Switches and receptacles are electrical devices. There are many variations of each, so we will discuss only the most common of each. Switches Four of the most commonly used switches are the single-pole, double-pole, three-way, and four-way switches. These switches are available in 15-amp and 20-amp ratings. Be sure to use the correct amp rating when installing a switch in a lighting branch circuit. Single-pole switch This switch is used when a light or fan is turned on or off from only one location. Double-pole switch This switch is used when two separate circuits must be controlled with one switch. They are used to control 240-volt loads, such as electric heat, motors, and electric clothes dryers. Three-way switch This switch is used when a light or fan can be turned on or off from two different locations. Four-way switch This switch is used when a light or fan can be turned on or off from three or more different locations. This switch must be used with two three-way switches. - -- Single-pole switch: MOUNTING EARS MOUNTING STRAP TOGGLE GROUNDING TERMINAL 6-32 MOUNTING SCREW TERMINALS 6-32 MOUNTING SCREW OFF -- MOUNTING EARS MOUNTING EARS MOUNTING STRAP TOGGLE LINE TERMINAL LINE TERMINAL GROUNDING TERMINAL LOAD TERMINAL LOAD TERMINAL 6-32 MOUNTING SCREW 6-32 MOUNTING SCREW OFF -- Double-pole switch -- NOTE: SWITCH HAS NO "ON/OFF" DESIGNATION GROUNDING TERMINAL TRAVELER TERMINAL TRAVELER TERMINAL COMMON TERMINAL (DARK) TOGGLE SWITCH 6-32 MOUNTING SCREW 6-32 MOUNTING SCREW -- Three-way switch - NOTE: SWITCH HAS NO "ON/OFF" DESIGNATION GROUNDING TERMINAL TRAVELER TERMINAL TRAVELER TERMINAL TRAVELER TERMINAL TRAVELER TERMINAL TOGGLE SWITCH 6-32 MOUNTING SCREW 6-32 MOUNTING SCREW -- Four-way switch -- Receptacles Many types of receptacles are available. The most common receptacles are: 240-volt 30-amp or 50-amp single receptacle 240-volt 20-amp single receptacle 120-volt 15-amp or 20-amp single receptacle 120-volt 15-amp or 20-amp duplex receptacle 120-volt 15-amp or 20-amp ground fault circuit interrupter (GFCI) receptacle The 240-volt 30-amp single receptacle is generally used as a clothes dryer receptacle. It has four wires that are connected to it: two ungrounded conductors (hot wires), one grounded conductor (neutral), and one grounding conductor (bare ground wire). The 240-volt 50-amp single receptacle is generally used as an electric range (stove) receptacle. It also has four wires that are connected to it, as mentioned above. The 240-volt 20-amp single receptacle is generally used as an air conditioner receptacle. As the previous receptacles, it also has four wires that are connected to it. Notice the slots on the front of the receptacle. The 120-volt 15/20-amp single receptacle is used most often for electrical utilization equipment that requires a 20-amp branch circuit. This is so a 15-amp- or a 20-amp-cord can be plugged into it. Any receptacle devices that are 120 volt, 20 amp rated will have this feature. The 120-volt 15-amp duplex receptacle is the most common receptacle in use today. The 120-volt 15/20-amp duplex receptacle is similar to the previous receptacle except that it has the "T" slot to accommodate a 20-amp load. See procedures for "Installing Duplex Receptacles in a Nonmetallic Electrical Outlet Box" and "Installing Duplex Receptacles in a Metal Electrical Outlet Box." The GFCI duplex receptacle is designed to trip when there is a difference between the current going to the load and the current returning from the load. This device will trip if there is a difference of 4 mA between the two. This device is easily recognizable because of the Trip and Reset buttons that are on the face of the receptacle. Once this receptacle is properly installed on a branch circuit, every device and fixture connected to the branch circuit past the GFCI receptacle is protected. This receptacle is to be used above countertops in bathrooms and kitchens, in wet or damp locations (such as basements), and outside. This receptacle is also available in 15 amp and 20 amp. See procedure for "Installing Feed Through GFCI and AFCI Duplex Receptacles in Nonmetallic Electrical Outlet Boxes." -- Single and duplex receptacle: A MULTIPLE RECEPTACLE THIS IS A RECEPTACLE A SINGLE RECEPTACLE -- Ground fault circuit interrupter receptacles (GFCI) Fixtures Various types of lighting fixtures are available today. Only the most common types will be discussed in this section. Fixtures are described by the way they mount and by the type of bulb that is used within them. For example, a surface-mount, incandescent, ceiling fixture is one that mounts against the ceiling surface and has an incandescent bulb, the most commonly used light bulb. It’s the standard frosted or clear light bulb that we use in our homes. It tends to give off a yellowish light when compared to a fluorescent light bulb. Fluorescent bulbs, most commonly referred to as tubes," tend to give off a white light. Here is a list of the most common light fixtures: Surface-mount incandescent fixture: mounts against ceiling or wall . See procedure for "Installing a Cable-Connected Fluorescent Lighting Fixture Directly to the Ceiling" Surface-mount fluorescent fixture: mounts against ceiling or wall . See the procedure for "Installing a Fluorescent Fixture (Troffer) in a Dropped Ceiling" Recessed-can incandescent lighting fixture: mounts in the ceiling . See procedure for "Installing a Strap on a Lighting Outlet Box Lighting Fixture" Pendant-type incandescent lighting fixture: hangs from the ceiling on a chain or cable (see --) Chandelier-type lighting fixture: multiple lamp fixtures hang from the ceiling on a chain or cable -- Surface-mount incandescent fixture -- Surface-mount fluorescent fixture -- Recessed-can incandescent lighting fixture -- Pendant-type incandescent lighting fixture -- Chandelier-type lighting fixture Electrical Maintenance Procedures As mentioned earlier, facilities maintenance technicians are more likely to maintain an existing electrical system as opposed to installing a new system. Therefore the technician should have a good understanding of the troubleshooting process as well as the proper technique for maintaining electrical systems. Troubleshooting Troubleshooting is a process in which a person gathers information and forms a logical conclusion as to the problems that may be present within the system. All problems should be looked at logically. Take time and consider the most logical problems that would cause the symptoms that are present in the faulty circuit. If you do this, you have a higher chance of success in finding and fixing the problem. All problems that occur in a system will give tell-tale signs that will help you find the problem. Training is always beneficial. This gives you a knowledge base that will help you form the logical conclusions needed to solve problems with the system. Troubleshooting occurs while you are gathering the information about the faulty system. Diagnosing begins while the data are being collected and is completed when a decision as to what the problem may be is formulated. Once you have diagnosed a problem, you must prove the diagnosis and repair the problem. A simplified, step-by-step guideline that could be used while troubleshooting follows. Remember: Don’t perform any of the following steps unless you are a qualified individual. 1. You are notified of a problem. 2. Ask the person who has reported the problem as many questions as possible as to what was witnessed during the failure. This may include something that was seen, smelling a distinct or peculiar odor, or feeling heat in the general vicinity of the problem. 3. Begin troubleshooting while making sure that all safety standards are adhered to. It’s a good idea to start troubleshooting at the most logical area that would cause the described symptoms. You should start diagnosing the problem as soon as you receive the descriptions given to you and as you start receiving data from troubleshooting. 4. Safely remove any covers or panels that will give you access to the part of the electrical system that you are troubleshooting. 5. Visually inspect the equipment and devices for any signs of overheating or disintegration. If signs are visible, go to step 6a. If signs are not visible, go to step 6b. 6a. Be sure that you are qualified to work on the device and equipment before working on any part of an electrical system. De-energize the circuit or system, attach your lock-out/tag-out device to the disconnecting means, and place the key in your pocket. Go to step 7. 6b. Take the appropriate step to safely acquire voltage and/or current readings at the suspected device or equipment. If your readings indicate that voltage is present and current is not following as it should be, the suspected device or equipment may be faulty and it may need to be replaced. If you decide to re place the faulty device or equipment, de-energize the circuit or system, attach your lock-out/tag-out device to the disconnecting means, and place the key in your pocket; then go to step 7. 7. Go back to the device or equipment and verify that the circuit is in fact de-energized. 8. Once it has been verified that the circuit is de-energized, begin working on your fault. **In the event that you may need to repair and/or replace common electrical devices such as receptacles, switches, interior and exterior lighting fixtures, bulbs, or ballasts, follow the simple procedures listed in the last section of this section. 9. Once the fault is repaired, and all covers are back in place, remove the lock-out/ tag-out from the source of energy and re-energize the circuit. 10. Go back to the device or equipment that was replaced and verify that it’s working properly. If it is, inform the person who called the job in. If it’s not working, you may want to consider calling a qualified electrician to troubleshoot and diagnose the problem. Perform Tests Regularly perform tests on the following to ensure that they are operating properly before an emergency arises: Smoke alarms Fire alarms Medical alert systems Emergency exit lighting GFCI receptacles Test Smoke Alarms and Fire Alarms Individual smoke and fire alarms typically have a test button that can be pushed. Be aware that pushing the test button on any one alarm may set off all alarms that are on the system as the fire alarm code requires all of them to be tied together. Some fire alarm systems may require you to put the system in test mode before testing. If this is not done and the fire alarm is activated during the test, the sprinkler systems may activate. Placing the fire alarm system in test mode would allow the electrical portion of the system to be tested without the sprinklers activating during the test. Be sure to repair or replace any defective alarm or smoke detector according to manufacturer's specifications and wiring diagrams, and report any malfunctions to your supervisor. Many of the smoke detectors have a 9-volt battery in them so that the alarm can continue to work in the event that there is a loss of power. The batteries should be checked on a regular basis. If a detector is found to have a dead or weak battery, the battery should be changed immediately. If the smoke detector does not operate properly, it should be changed immediately. Smoke detector To test a smoke detector: 1. Press the battery-test button on the unit to make sure the battery is properly connected. 2. If the unit has a battery that's more than a year old, replace the battery. 3. Light a candle and hold it approximately 6 inches below the detector so that heated air will rise into the unit. 4. If the alarm doesn't sound within 20 seconds, blow out the candle and let the smoke rise into the unit. 5. If the alarm still doesn't sound, open the unit up and make sure it’s clean and that all electrical connections are solid. 6. If, again, the alarm doesn't sound, replace the smoke detector. To replace a smoke detector battery: 1. Remove the smoke detector cover, typically by carefully pulling down on the case's perimeter or twisting the case counterclockwise. 2. Locate and remove the battery. 3. Replace it with a new one. 4. Close the case and test the smoke detector. Read the owner's manual for additional troubleshooting tips and possible adjustments. Test GFCI Receptacles 1. Go to the receptacle and locate the "Test" button. 2. Press the test button and listen for a very light "pop" in the receptacle. You may also notice a small indicator that will light up after you have tripped the GFCI. If the GFCI tripped, then it’s working correctly. 3. Press the "Reset" button, and the GFCI should reset and the indicator (if preset) will turn off. 4. If it did not trip, press the test button again. If the GFCI still does not trip, then it’s faulty and needs to be replaced, or it could have been wired incorrectly and therefore would need to be rewired correctly. Test Medical Alert Systems Assisted living facilities may have and hospitals will have medical alert systems. If your facility has medical alert systems, all tests that are conducted on these systems must be performed according to the manufacturer's specifications and should be per formed only by qualified personnel who have been properly trained on the proper test procedures for that system. If any defects are found in the system, they should be reported to your supervisor immediately. -- Lock-out/tag-out devices -- Removing faulty detector -- Interconnected smoke detectors: 120-VOLT CIRCUIT PLUG-IN POWER BLOCK ON REAR OF ALARM SMOKE ALARMS BATTERY COMPARTMENT CEILING OUTLET BOXES IN CEILING Replace Detectors, Devices, Fixtures, and Bulbs Be sure that as you replace or repair any defective equipment or devices, you do so according to the manufacturer's specifications. Also, don't forget to report any mal functions to your supervisor. -- Mounting base still attached to box. Replace Smoke Detectors 1. Acquire a fiberglass or nonconductive ladder that will be tall enough for you to reach the detector once you are on it. Don’t use an aluminum ladder. Set the ladder up under the faulty detector, making sure that all four legs of the ladder are solidly in place. 2. Go to the panel and de-energize the branch circuit that supplies the smoke detectors. 3. Lock out/tag out the breaker. 4. Go back to the faulty detector and remove it from its mounting base by twisting the detector body in a counterclockwise direction. The detector should release from the base. 5. Make a note of how the smoke detector is wired. If necessary, make a sketch on a piece of paper to follow when you are reconnecting the power leads. You may find that the smoke detector you are replacing has a quick connector plug on the back of the smoke detector. If you are replacing the faulty detector with a new one that is the same model, simply unplug the quick connect from the smoke detector. If a quick connect is not present, you may have to disconnect the power leads from the smoke detector by removing the wirenuts. There should be three leads on a newer type of smoke detector. One will be black, one white, and one orange. The black wire is the hot wire, the white wire is the neutral, and the orange wire is for the repeating circuit. (This wire triggers all of the other smoke alarms.) 6. If you are replacing the faulty detector with a new one that is the same model, you may be able to leave the mounting base mounted to the ceiling. If you are replacing the faulty smoke detector with a different brand or model, you may find that the base of the old one won’t work for the new one, and that the old mounting base must therefore be removed. This can be accomplished by loosening the two screws that are holding the base to the box. Once the base is loose, simply twist it in a counterclockwise direction as you did with the detector. The mounting base should release from the box. Now replace the old base with the new base and tighten the screws. 7. Reconnect the power leads. If you are replacing an older two-wire model with a newer three-wire model, you won’t need to use the orange lead. Simply cap the orange lead and stuff it into the box. 8. Set the new detector up against the mounting base, and twist it in a clockwise direction until it’s securely mounted. 9. Go to the panel, remove your lockout from the breaker, and turn on the breaker. If the breaker does not trip, go to the next step. If the breaker trips, set the breaker to the off position and lock it out again. Go back to the detector, remove it from the base, and visually inspect the connections. Be sure that there is no exposed copper wire on the black lead that could be touching the bare copper ground wire. Once you think everything is correct, put the detector back on its base, go back to the panel, remove your lockout from the breaker, and turn the breaker back on. If the breaker trips again, call a qualified electrician to troubleshoot the problem. If the breaker does not trip, go to the next step. 10. Go back to the detector and verify that it’s working correctly. 11. Gather all tools and ladders, and clean up the area that you were working in. Replace a Switch To remove the old switch: 1. Shut off the power at the circuit breaker box. 2. Remove the cover plate and test the terminals with the circuit tester. If the tester does not light up, there is no power going to the switch. 3. Remove the screws that hold the switch in place, and pull the switch from the wall. 4. Loosen the screws holding the wires to the switch, remove the wires, and remove the switch. In some newer switches, the wires may go directly into the switch, where they are held in place by clamps inside the switch. These switches usually have a slot into which you can insert a small screwdriver to loosen the clamps. To install the new switch: 1. Begin by bending the end of the ground wire into a small hook, placing the hook over the ground terminal of the switch, and tightening it into place. 2. Attach the remaining wires to the terminals and tighten them in the same way. Your new switch may have holes that allow you to insert the wires with out using the terminal screws. If so, straighten the wires, press them into the holes as far as they will go, and then tug on them to make sure they are held securely in place. 3. Gently press the switch back into position and secure it in place with screws. Then replace the switch cover, and turn on the power at the circuit breaker box. -- Cover plate -- Cover plate removed -- Replacement switch -- New switch Replace a Receptacle The following steps should be used to replace an existing receptacle: 1. Turn the power off to the receptacle. 2. Test the receptacle to ensure that the power is off. 3. Remove the cover plate and receptacle from the box. 4. Mark the common wire with a piece of tape. The common wire terminal of the receptacle will have a different color from that of the other terminals. 5. Detach the common wire from the old receptacle, followed by the neutral and ground wires. 6. Locate the common terminal on the new receptacle and attach the wire. Remember that the common terminal will have a different color. 7. Attach the neutral and ground wires to the new receptacle. 8. Push the receptacle back into the box. 9. Install the receptacle cover onto the new receptacle. 10. Turn the power back on. ---- Ground fault circuit interrupter (GFCI) LINE-SIDE OF THE GFCI PROVIDES POWER TO THE RECEPTACLE. THE RECEPTACLE IS AUTOMATICALLY PROTECTED AGAINST GROUND FAULTS WHEN IT IS PROPERLY CONNECTED TO THE CIRCUIT. WHEN LOAD-SIDE CONDUCTORS ARE CONNECTED TO THE TERMINALS MARKED LOAD, EVERY DEVICE, APPLIANCE, OR OTHER EQUIPMENT ON THE LOAD-SIDE OF THE GFCI WILL ALSO HAVE GFCI PROTECTION. THE PROTECTION OF LOAD-SIDE COMPONENTS IS SOMETIMES REFERRED TO AS A FEED-THROUGH. A GFCFI RECEPTACLE TAKES UP A LOT OF ROOM IN THE BOX. TEST RESET LOAD LINE LOAD-SIDE PHASE CONDUCTOR TERMINAL LINE-SIDE PHASE CONDUCTOR TERMINAL EQUIPMENT GROUNDING CONDUCTOR TERMINAL FRONT BACK LOAD-SIDE CONDUCTOR PAIR LINE-SIDE CONDUCTOR PAIR LOAD-SIDE NEUTRAL CONDUCTOR TERMINAL TEST BUTTON LINE-SIDE NEUTRAL CONDUCTOR TERMINAL RESET BUTTON --- Replace a GFCI Receptacle A GFCI receptacle has a line side and a load side. If the GFCI receptacle has only one black and one white wire terminated to it (not counting the ground wire), then both wires are to be terminated to the line side of the GFCI receptacle while making sure to connect the black wire to the brass-colored screw, the white wire to the silver screw, and the bare wire (if present) to the green colored screw. If other receptacles on the branch circuit are fed through the GFCI receptacle, there will be five wires on the receptacle: two black wires, two white wires, and one ground wire. If this is the case, terminate the wires that are feeding the line volt age into the GFCI receptacle to its line side. The wires that are feeding the remaining receptacles on the branch circuit should be connected to the load side of the GFCFI receptacle. Replace or Repair a Light Fixture (120-Volt Outlet) 1. Turn off both the branch circuit and the main power at the service panel. Work in the daytime so that you can use natural light to light the work area. Also use a flashlight if needed. 2. Remove the plate and the outlet mounting screws (see --). 3. Pull the outlet with wires still attached about 4-6 inches out of the junction box. 4. Note the color of the wires and identify the hot ground, neutral ground, and device ground. 5. Unscrew the terminal screws that attach the wire to the outlet and remove the wire. Start with the hot, then the neutral, and finally the ground. 6. Examine the new outlet. Identify which wire connects to which terminal. It does not matter which set of vertical screws you attach the wire to. If the outlet does not have markings indicating the polarity, then remember that the bright brass screw connects to your hot wire. 7. Using needle-nose pliers, connect the ground to the green terminal on the bottom of the outlet. Then connect the white wire to the neutral or silver terminal, and finally the hot wire to the hot or brass terminal. The wire should be wrapped completely around the terminal screws. 8. Finally, tuck the wires back in the junction box, and mount the outlet and the outlet plate. Note: Make sure the outlet is rated for the amperage of the circuit. Don’t use an outlet rated at 15 amp on a 20-amp circuit. Replace a Light Bulb 1. Turn off the lamp or light fixture. 2. Allow a hot bulb to cool before touching it. 3. Grasp the bulb lightly but firmly and turn counterclockwise until it’s released from the socket. 4. Insert a replacement bulb lightly but firmly into the socket, and turn it clockwise until it’s snug. 5. Turn the lamp or fixture back on. 6. Dispose of the used bulb. Replace a Fluorescent Bulb 1. Make sure the light switch is turned off. 2. Remove the lens or diffuser to access the bulb . On most fluorescent lights, the lens or diffuser is a plastic panel below the bulb . Push the panel up and tilt to remove. 3. Check to make sure that the problem is not something as simple as a poor con tact. This can usually be corrected by giving the bulb a gentle turn a few degrees and then back to the lock position. -- Removing light bulb -- Face plate -- Ballast on a fluorescent fixture -- Fluorescent light bulb : Lens/diffuser on a fluorescent fixture 4. Hold the old bulb firmly at one end and rotate it one quarter-turn clockwise. This should put the end prongs in line with the loading slot. 5. Slide the bulb free. 6. Lower the end of the bulb carefully out of the socket. When one end is free, pull slightly and the other end should come out also. 7. Set the old bulb aside and lift a new bulb into the fixture. 8. Hold the bulb horizontally and rotate the new bulb until the prongs on each end are lined up with the grooves in the socket. 9. Insert the prongs in the socket, and rotate the bulb a quarter-turn in a counter clockwise direction. The bulb should click into place on each end. 10. Test the light at the switch. If the light still doesn't come on, you may need to replace the ballast. Replacing a Fluorescent Ballast 1. Find the ballast, which is usually seated near one end of the bulb. It’s a silver, cylinder-shaped item with a diameter similar to that of a quarter. The ballast provides the starting voltage and then stabilizes the current for the fluorescent bulb (see --). 2. Loosen the ballast by turning it ¼- to ½-turn counterclockwise. 3. Pull the ballast out of the fixture. Take it to a hardware or electrical supply store to match it with a new one. 4. Insert a new ballast into the light fixture; twist clock wise to lock into position. Always check manufacturer's instruction before installing any electrical parts and/or devices. 5. Replace the lens cover. Test and Replace Fuses Identify and Replace Blown Fuses 1. Open the door to your service panel, and examine it to locate the blown fuse. For light and receptacle circuits, look for a break or blackened area visible through the glass of a screw-in plug fuse . If all the fuses look good, identify the fuse according to the circuit map printed on the door of the service panel or next to each fuse. 2. If the circuits are not mapped, locate the fuse by trial and error. Remove the fuses one at a time, and insert a new fuse to test the circuit. You can also test the fuse with a continuity tester. Touch the pointed probe of a continuity tester to the fuse's tip and the clip to its threaded shaft. If the tester does not glow, the fuse is bad. 3. For fuse blocks , which protect an electric stove and the main circuit, pull straight out on the handle and remove the individual cartridge fuses from the block using a cartridge-fuse puller. Test the fuses with a continuity tester by probing the two ends. Install a New Fuse 1. Screw in a new plug fuse, or install a new cartridge fuse in the fuse block and press the block back in. The replacement should always have the same rating as the original. 2. If all of the circuits have stopped working, remove and test the cartridge fuses in the main fuse block, usually located at the top left. (Occasionally it’s reversed with the stove circuit on the top right.) Replace any faulty ones. Reset a Circuit Breaker 1. Push the breaker switch to the "off" position and then back fully to the "on" position. 2. There will be a click as it snaps into the "on" position. If the breaker trips again, you need to determine the reason for the overcurrent condition and correct the root cause of the problem. The breaker may be tripping due to excessive amperage in the circuit or may be shorting out. -- Screw in fuse -- Fuse block ----- Procedures: Using a Voltage Tester In this example, we will determine which conductor of a circuit is grounded using a voltage tester. Put on safety glasses, and observe regular safety procedures. A. Connect the tester between one circuit conductor and a well established ground. If the tester indicates a voltage, the conductor being tested is not grounded. B. Continue this procedure with each conductor until zero voltage is indicated between the tested conductor and the known ground. Zero voltage indicates that you have found a grounded circuit conductor. C. Connect the tester between the two conductors. Read the indicated voltage value on the meter. Note: With a solenoid type tester, you should also feel a vibration that is another indication of voltage being present. In this example, we will determine the approximate voltage between two conductors using a voltage tester. Put on safety glasses and observe regular safety procedures. 120 VOLTS 240 VOLTS 120 VOLTS VOLTAGE TESTER 120 VOLTS INDICATED KNOWN GROUND NO VOLTS INDICATED KNOWN GROUND ---- Using a Noncontact Voltage Tester NONCONTACT VOLTAGE TESTER THE TESTER WILL PROVIDE A VISUAL OR AUDIBLE INDICATION IF THERE IS A VOLTAGE PRESENT. TESTER IS LIT UP. A VOLTAGE IS PRESENT. Procedures In this example, we will determine if an electrical conductor is energized using a noncontact voltage tester. Put on safety glasses and observe regular safety procedures. Identify the conductor to be tested. A. Bring the noncontact voltage tester close to the conductor. Note that some noncontact voltage testers may have to be turned on before using. Listen for the audible alarm, observe a light coming on, or feel a vibration to indicate that the conductor is energized. -- Using a Clamp-On Ammeter LOAD THAT IS DRAWING 10 AMPS AT 240 VOLTS In this example, we will be measuring current flow through a conductor with a clamp-on ammeter. Note that you can take a current reading with a clamp on ammeter clamped around only one conductor. For example, a clamp-on meter won’t give a reading when clamped around a two-wire Romex cable. Put on safety glasses and observe regular safety procedures. If the meter is analog and has a scale selector switch, set it to the highest scale. Skip this step if the meter is digital and has an autoranging feature. A. Open the clamping mechanism and clamp it around the conductor. Read the displayed value. -- Installing Old-Work Electrical Boxes in a Sheetrock Wall or Ceiling MADISON HOLD-ITS OUTSIDE WALL VIEW INSIDE WALL VIEW OLD-WORK DEVICE BOX Put on safety glasses and follow all applicable safety rules. Determine the location where you want to mount the box and make a mark. Make sure there are no studs or joists directly behind where you want to install the box. Turn the old-work box you are installing backward, and place it at the mounting location so the center of the box is centered on the box location mark. Trace around the box with a pencil. Don’t trace around the plaster ears. Using a keyhole saw, carefully cut out the outline of the box. There are two ways to get the cut started. One way is to use a drill and a l at blade bit (say a ½-inch size), drill out the corners, and start cutting in one of the corners. The other way used often is to simply put the tip of the keyhole saw at a good starting location and, with the heel of your hand, hit the keyhole saw handle with enough force to cause the blade to go through the sheetrock. It usually does not require much force to start the cut this way. A. Assuming that a cable has been run to the box opening, secure the cable to the box and insert it into the hole. Secure the box to the wall or ceiling surface with Madison hold-its, or use a metal or nonmetallic box with built-in drywall grips. Wear safety glasses and observe all applicable safety rules. Installing Duplex Receptacles in a Nonmetallic Electrical Outlet Box A. Using a wire stripper, remove approximately ¾” of insulation from the end of the insulated wires. B. Using long-nose pliers or wire strippers, make a loop at the end of each of the wires. Place the loop on the black wire around a brass terminal screw so that the loop is going in the clockwise direction. While pulling the loop snug around the screw terminal, tighten the screw to the proper amount with a screwdriver. Place the loop on the white wire around a silver terminal screw so that the loop is going in the clockwise direction. While pulling the loop snug around the screw terminal, tighten the screw to the proper amount with a screwdriver. C. Complete the installation by placing the loop on the bare grounding wire around the green terminal screw so that the loop is going in the clockwise direction. While pulling the loop snug around the screw terminal, tighten the screw to the proper amount with a screwdriver. -- D. Place the receptacle into the outlet box by carefully folding the conductors back into the device box. E. Secure the receptacle to the device box using the 6-32 screws. Mount the receptacle so that it’s vertically aligned. F Attach the receptacle cover plate to the receptacle. Be careful not to tighten the mounting screw(s) too much. Plastic faceplates tend to crack very easily. Procedures: Installing Duplex Receptacles in a Metal Electrical Outlet Box Wear safety glasses and observe all applicable safety rules. A. Attach a 6-8-inch-long grounding pigtail to the metal electrical outlet box with a 10-32 green grounding screw. The pigtail can be a bare or green insulated copper conductor. B. Attach another 6-8-inch-long grounding pigtail to the green screw on the receptacle. C. Using a wirenut, connect the branch-circuit grounding conductor(s), the grounding pigtail attached to the box, and the grounding pigtail attached to the receptacle together. Using a wire stripper, remove approximately ¾” of insulation from the end of the insulated wires. Using long-nose pliers or wire strippers, make a loop at the end of each of the wires. Place the loop on the black wire around a brass terminal screw and the loop on the white wire around a silver terminal screw so that the loops are going in the clockwise direction. Tighten the screws to the proper amount with a screwdriver. Place the receptacle into the outlet box by carefully folding the conductors back into the device box. Secure the receptacle to the device box using the 6-32 screws. Mount the receptacle so that it’s vertically aligned. Attach the receptacle cover plate to the receptacle. Be careful not to tighten the mounting screw(s) too much. Plastic faceplates tend to crack very easily. Procedures: Installing Feed-Through GFCI and AFCFI Duplex Receptacles in Nonmetallic Electrical Outlet Boxes Wear safety glasses and observe all applicable safety rules. At the electrical outlet box containing the GFCI or AFCI feed through receptacle, use a wirenut to connect the branch-circuit grounding conductors and the grounding pigtail together. Connect the grounding pigtail to the receptacle's green grounding screw. At the electrical outlet box containing the GFCI or AFCI feed through receptacle, identify the incoming power conductors, and connect the white grounded wire to the line-side silver screw and the incoming black ungrounded wire to the line-side brass screw. At the electrical outlet box containing the GFCI or AFCI feed-through receptacle, identify the outgoing conductors and connect the white grounded wire to the load-side silver screw and the outgoing black ungrounded wire to the load-side brass screw. Secure the GFCI or AFCI receptacle to the electrical box with the 6-32 screws provided by the manufacturer. A proper GFCI or AFCI cover is provided by the device manufacturer; attach it to the receptacle with the short 6-32 screws provided. At the next "downstream" electrical outlet box containing a regular duplex receptacle, connect the white grounded wire(s) to the silver screw(s) and the black ungrounded wire(s) to the brass screw(s) in the usual way. Place a label on the receptacle that states "GFCI Protected." These labels are provided by the manufacturer. Continue to connect and label any other "downstream" duplex receptacles as outlined in the previous step. Procedures: Installing a Light Fixture Directly to an Outlet Box Connect the white grounded conductor(s) to the silver screw or white fixture pigtail. If there is one grounded conductor in the box, strip approximately ¾” (19 mm) of insulation from the end of the conductor, and form a loop at the end of the conductor using an approved tool such as a T-stripper. Once the loop is made, slide it around the silver terminal screw on the fixture, so the end is pointing in a clockwise direction. Hold the conductor in place and tighten the screw. If there are two or more grounded conductors in the box, strip the ends as described previously, and use a wirenut to connect them and a white pigtail together. Attach the pigtail to the silver grounded screw as described previously. The black ungrounded conductor(s) is connected to the brass-colored terminal screw on the fixture. The connection procedure is the same as for the grounded conductor(s). Now the fixture is ready to be attached to the lighting outlet box. Make sure the grounding conductors are positioned so they won’t come in contact with the grounded or ungrounded screw terminals. Align the mounting holes on the fixture with the mounting holes on the lighting outlet box. Insert the 8-32 screws that are usually equipped with the fixture through the fixture holes. Then thread them into the mounting holes in the outlet box. Tighten the screws until the fixture makes contact with the ceiling or wall. Be careful not to overtighten the screws, as you may damage the fixture. Install the proper lamp, remembering not to exceed the recommended wattage. Turn on the power and test the light fixture. Put on safety glasses and observe all applicable safety rules. Using a voltage tester, verify that there is no electrical power at the lighting outlet where the fixture will be installed. If electrical power is present, turn off the power and lock out the circuit. Locate and identify the ungrounded, grounded, and grounding conductors in the lighting outlet box. A The grounding conductor won’t be connected to this fixture. If there is a grounding conductor in a nonmetallic box, simply coil it up and push it to the back or bottom of the electrical box. Don’t cut it off, as it may be needed if another type of light fixture is installed at that location. If there are two or more grounding conductors in a nonmetallic box, connect them together with a wirenut and push them to the back or bottom of the lighting outlet box. If there is a grounding conductor in a metal outlet box, it must be connected to the outlet box by means of a listed grounding screw or clip. If there are two or more grounding conductors in a metal box, use a wirenut to connect them together along with a grounding pigtail. Attach the grounding pigtail to the metal box with a listed grounding screw. Procedures: Installing a Cable-Connected Fluorescent Lighting Fixture Directly to the Ceiling Put on safety glasses and observe all applicable safety rules. Using a voltage tester, verify that there is no electrical power at the lighting outlet where the fixture will be installed. If electrical power is present, turn off the power and lock out the circuit. Place the fixture on the ceiling in the correct position, making sure it’s aligned and the electrical conductors have a clear path into the fixture. Mark on the ceiling the location of the mounting holes. Use a stud finder to determine if the mounting holes line up with the ceiling trusses. If they do, screws will be used to mount the fixture. If they do not, toggle bolts will be necessary. For some installations, a combination of screws and toggle bolts will be required. If screws are used, drill holes into the ceiling using a drill bit that has a smaller diameter than the screws to be used. This will make installing the screws easier. If toggle bolts are to be used, use a l at-bladed screwdriver to punch a hole in the sheetrock only large enough for the toggle to fit through. Remove a knockout from the fixture where you wish the conductors to come through. Install a cable connector in the knockout hole. Place the fixture in its correct position, and pull the cable through the connector and into the fixture. Tighten the cable connector to secure the cable to the fixture. This part of the process may require the assistance of a coworker. Using toggle bolts, put the bolt through the mounting hole and start the toggle on the end of the bolt. With a coworker holding the fixture, install the mounting screws or push the toggle through the hole until the wings spring open. This will hold the fixture in place until the fixture is secured to the ceiling. Make the necessary electrical connections. The grounding conductor should be properly wrapped around the fixture grounding screw and the screw tightened. The white grounded conductor is connected to the white conductor lead; then the black ungrounded conductor is connected to the black fixture conductor. Install the wiring cover by placing one side in the mounting clips, squeezing it, and then snapping the other side into its mounting clips. Install the recommended lamps. Usually, they have two contact pins on each end of the lamp. Align the pins vertically, slide them up into the lamp holders at each end of the fixture, and rotate the lamp until it snaps into place. Test the fixture and lamps for proper operation. Install the fixture lens cover. Procedures: Installing a Strap on a Lighting Outlet Box Lighting Fixture Put on safety glasses and observe all applicable safety rules. Using a voltage tester, verify that there is no electrical power at the lighting outlet where the fixture will be installed. If electrical power is present, turn off the power and lock out the circuit. Before starting the installation process, read and understand the manufacturer's instructions. A Mount the strap to the outlet box using the slots in the strap. With metal boxes, the screws are provided with the box. With nonmetallic boxes, you must provide your own 8-32 mounting screws. Put the 8-32 screws through the slot and thread them into the mounting holes on the outlet box. Tighten the screws to secure the strap to the box. Identify the proper threaded holes on the strap, and install the fixture-mounting headless bolts in the holes so the end of the screw will point down. Make the necessary electrical connections. Make sure that all metal parts (including the outlet box), the strap, and the fixture are properly connected to the grounding conductor in the power feed cable. Neatly fold the conductors into the outlet box. Align the headless bolts with the mounting holes on the fixture. Slide the fixture over the headless bolts until the screws stick out through the holes. Don’t be alarmed if the mounting screws seem to be too long. Thread the provided decorative nuts onto the headless bolts. Keep turning the nuts until the fixture is secured to the ceiling or wall. Install the recommended lamp, and test the fixture operation. Install any provided lens or globe. They are usually held in place by three screws that thread into the fixture. Start the screws into the threaded holes, position the lens or globe so it touches the fixture, and tighten the screws until the globe or lens is snug. Don’t overtighten the screws. You may return the next day and find the globe or lens cracked or broken. Procedures: Installing a Chandelier-Type Light Fixture Using the Stud and Strap Connection to a Lighting Outlet Box Put on safety glasses and observe all applicable safety rules. Using a voltage tester, verify that there is no electrical power at the lighting outlet where the fixture will be installed. If electrical power is present, turn off the power and lock out the circuit. Before starting the installation process, read and understand the manufacturer's instructions. A Install the mounting strap to the outlet box using 8-32 screws. Thread the stud into the threaded hole in the center of the mounting strap. Make sure that enough of the stud is screwed into the strap to make a good secure connection. Measure the chandelier chain for the proper length, remove any unneeded links, and install one end to the light fixture. Thread the light fixture's chain- mounting bracket on to the stud. Remove the holding nut and slide it over the chain. Slide the canopy over the chain. Attach the free end of the chain to the chain-mounting bracket. Weave the fixture wires and the grounding conductor up through the chain links, being careful to keep the chain links straight. Section 410.28(F) of the NEC states that the conductors must not bear the weight of the fixture. As long as the chain is straight and the conductors make all the bends, the chain will support the fixture properly. Now run the fixture wires up through the fixture stud and into the lighting outlet box. Make all necessary electrical connections. Slide the canopy up the chain until it’s in the proper position. Slide the nut up the chain and thread it on to the chain-mounting bracket until the canopy is secure. Install the recommended lamp, and test the fixture for proper operation. Put on safety glasses and observe all applicable safety rules. Before starting the installation process, read and understand the manufacturer's instructions. During the rough-in stage, mark the location of the fixtures on the ceiling. Using standard wiring methods, place lighting outlet boxes on the ceiling near the marked fixture locations, and connect them to the lighting branch circuit. Once the dropped ceiling grid has been installed by the ceiling contractor, install the fluorescent light fixtures in the ceiling grid at the proper locations. Some electricians refer to this action as "laying in" the fixture. Once the fixture is installed, some electricians refer to the fixtures as being "laid in." A Support the fixture according to NEC requirements. Section 410.16(C) requires that all framing members used to support the ceiling grid be securely fastened to each other and to the building itself. The fixtures themselves must be securely fastened to the grid by an approved means, such as bolts, screws, rivets, or clips. This is to prevent the fixture from falling and injuring someone. Using a voltage tester, verify that there is no electrical power at the lighting outlet where the fixture will be installed. If electrical power is present, turn off the power and lock out the circuit. B Connect the fixture to the electrical system. This is done by means of a "fixture whip." A fixture whip is often a length of Type NM , Type AC, or Type MC cable. It can also be a raceway with approved conductors such as flexible metal conduit or electrical nonmetallic tubing. The fixture whip must be at least 18 inches (450 mm) long and no longer than 6 feet (1.8 m). Make all necessary electrical connections. The fixture whip should already be connected to the outlet box mounted in the ceiling. Using an approved connector, connect the cable or raceway to the fixture outlet box and run the conductors into the outlet box. Make sure that all metal parts are properly connected to the grounding system. Connect the white grounded conductors together and then the black ungrounded conductors together. Close the connection box. Install the recommended lamps, and test the fixture for proper operation. Install the lens on the fixture. QUIZ : What is an emergency backup system used for? What is NM cable? What is a single-pole switch? What is a double-pole switch? How do three-way switches differ from a single- F pole switch? What is a GFCI? G What is a continuity tester? How is a smoke detector tested? How are GFCI tested? List the steps for replacing a smoke detector. Electrical Facilities Maintenance Electrical Troubleshooting and Maintenance Upon completion of this job sheet, you should be able to demonstrate your ability to perform basic maintenance and electrical troubleshooting. Choose an area in your facility, and take an inventory of the switches being used in the area. What types are being used, and what are they made of? List five types of receptacles and their uses. What is the most important thing to remember when working with electricity? Define troubleshooting. What is a GCFI receptacle, and what is its purpose? What is the purpose of a lock-out/tag-out device? Prev: Customer Service Skills |