Residential Electrical Inspection 2024 Questions with Correct Answers. Graded A+, Exams of Electrical and Electronics Engineering

Download Residential Electrical Inspection 2024 Questions with Correct Answers. Graded A+ and more Exams Electrical and Electronics Engineering in PDF only on Docsity! Residential Electrical Inspection 2024 Questions with Correct Answers. Graded A+ 100-amp 4 AWG 2 AWG AL SE cable - ANS150-amp 1 AWG 2/0 AWG AL SE cable 15-amp: #14/2 with ground NM - Lighting circuits and typical general-use receptacles in living area. Dishwasher. Disposal. Refrigerator/freezer. - ANS20-amp: #12/2 with ground NM - Receptacle and switches in kitchen, laundry, bathrooms, and dining rooms. Microwave, Dishwasher. Disposal. Refrigerator/freezer. Hydro massage tub. 200-amp 2/0 AWG 4/0 AWG AL SE cable - ANS 240-volt appliances are fed from two 120-volt conductors, each connected to a separate bus bar in the distribution panel. It is imperative that, when one of the circuits trips due to an over-current condition, both conductors are de-energized at the same time. For this reason, all breakers supplying 240 volts are required to have the handles tied together by a listed handle tie. - ANS 3-phase supplies have three hot (or ungrounded) conductors, and there may also be a neutral or grounded conductor. Each of these phases, or legs, carries 120 volts at a different phase from the others. How and from where power is taken in these phased supplies produces different types of supply current. The common services include 120, 240, 208 and 480 volts. - ANS 3-Wire Appliances, prior to the adoption of the 1996 NEC code revisions, 3-wire, 240V supplies were common. The cable assembly carries: 1. two 120-volt ungrounded (hot) conductors; and 2. one grounded (neutral) conductor. As there is no separate grounding means in this installation, the metal frame of the appliance was allowed to be bonded to the neutral. This is no longer allowed in new construction. - ANS4-Wire Appliances, since adoption of the 1996 NEC, all 240V circuits are required to be 4-conductor assemblies carrying: 1. two 120V ungrounded (hot) conductors; 2. one grounded (neutral) conductor; and 3. one equipment grounding conductor. 30-amp: #10/3 with ground NM - Water heater. Clothes dryer. Condensing unit. - ANS40-amp: #8/3 with ground NM 6/6/6/6 AL SER Oven. Cooktop. Range. 50-amp: #6/3 with ground NM 4/4/4/6 AL SER Oven. Cooktop. Range. - ANS100-amp: 3 AWG 1 AWG AL remote distribution panel A 240-volt circuit breaker also acts as the main disconnecting means in modern panels, disconnecting all the electrical power in the home. - ANS a GFCI breaker, or a correctly wired GFCI receptacle, can protect all outlets farther downstream. - ANSThere are four basic types of GFCI in common usage, and two or three of them are common in residential construction. They are: 1. GFCI breakers in the distribution panel; 2. GFCI receptacles at in-home locations; 3. stand-alone GFCIs, as sometimes used with pools; and 4. extension cords with built-in protection, primarily found on construction sites. A switch must not be installed within a wet location in a tub or shower space, unless it is installed as part of a listed tub or shower assembly.A surface-mounted switch located in a damp or wet location must be enclosed in a weatherproof enclosure. A flush-mounted switch in a damp or wet location must be equipped with a weatherproof cover. - ANSLights in contact with insulation should be IC-rated. If not, they should have 3 inches of clearance away from insulation or any other combustible surface or material. According to InterNACHI's Home Inspection S.O.P., the inspector is not required to: - ANS1. measure or determine the amperage or voltage of the main service equipment; 2. remove panelboard cabinet covers or dead fronts; 3. insert any tool, probe or device into the main panelboard, sub-panels, distribution panelboards, or electrical fixtures; or 4. operate any electrical disconnect or over-current protection devices. According to the 2008 NEC, crawlspaces and unfinished basements that have NM cable installed shall be drilled through the joists unless installed on a running board. Cables with three 8-awg or two 6-awg and larger shall be allowed on the surface of the aluminum and is considered safe. However, copper-clad should be sized the same as normal aluminum. Amps - ANSThe rate at which electricity flows through a conductor. I=W/E An electrical circuit requires a minimum of - ANSTwo wires through which electric current flows. Current is measured in amperes, which travels from a power source (such as the local utility), through the device it operates, called the load, and then back to the source to complete the circuit. In AC or alternating-current wiring, there are about 120 volts in the "hot" or energized wire. This voltage provides the momentum that forces the electrons to flow in the circuit. Most 120-volt circuits are wired to deliver 15 or 20 amps of current. Anti-oxidant paste is a grayish paste that is commonly found on older aluminum multi- strand conductors and is still required by some city electrical inspectors. This paste was designed to stop the aluminum from oxidizing, and thus be better able to maintain a clean contact footprint in its lug. - ANSAll abandoned wiring should be removed from the electrical panel, or, at the very least, it should be properly isolated so that the conductors are not able to make contact with any live components. any staircase with six or more risers should have 3-way switches at both the top and bottom of the run. - ANSSwitched receptacle circuits are allowed for all other locations: 1. living rooms; 2. dining rooms; 3. studies; 4. family rooms; 5. bedrooms; and 6. crawlspaces with mechanical equipment. armored cable (AC): Conductors protected by a spiral-wound outer metal sheathing. AC has been around since the early part of the century, and they gained wide acceptance in the 1930s, especially after the NEC's acceptance in the 1932 Code. - ANSType-AC cables fall into two categories: those with an internal bonding conductor and those without. In many cases, the sheathing itself, or its internal bond, has been used improperly as the grounding conductor, or, even worse, as the neutral conductor. As of 1959, the NEC has required that all type-AC cable includes a bonding strip which connects all the individual convolutions. The older "BX" cable did not have this, and the exterior metal casing was not meant to be an effective fault current path. Since the 1960s, a newer type of AC-cable assembly came onto the market. The improved MC cable includes a proper grounding conductor. - ANS Before even thinking about touching, inspecting or removing a dead front cover, the inspector should - ANSlook carefully for signs of water or moisture staining on the panel or on its surrounding wall. If there is any evidence of water, the inspector should recommend that the panel be fully evaluated and repaired by an electrical contractor, so delving further into the panel is not only potentially dangerous, it's also unnecessary. Before exploring these protocols, we must understand how receptacles should be correctly wired. 1. small slot: is the hot or ungrounded supply; 2. large slot: is the neutral or grounded return; and 3. round pinhole: is the grounding conductor. This is very important if the receptacle has reversed polarity (hot and neutral switched) because then things like lamp holder collars may become live and pose a great electrocution hazard. It is very common to find 3-prong receptacles with no ground, or, worse, receptacles with a false or bootleg ground where the grounding terminal has been illegally connected to the neutral. - ANSSome inspectors are now starting to check voltage drop along conductors. This falls well outside of industry standards of practice, but with electrical components becoming ever more sensitive to voltage fluctuations, many more inspectors will start to check for this. The National Electrical Code® recommends that voltage should not drop more than 3% on branch circuits, and a 5% overall drop, including the service itself. Bonding components - ANSAs discussed in the section on panel enclosures, they need to be bonded to the grounding system. But there is also a very long list of other components that need to be connected to ground, since they have the potential to become energized to electrical faults. These components include: 1. interior water piping; 2. water heaters; 3. around water meters; 4. gas lines; 5. electrical enclosures; 6. electrical raceways; 7. electric outlets or junction boxes; 8. CSST gas piping (manufacturer's compliance); and 9. telephone and cable TV systems. In more modern panels, the bonding connector is required to be through an approved green screw so it is more apparent to both the electrician and the code enforcement officer. However, in many panels, there may be a bonding strap or bonding bar. Closet Lights: Open incandescent lamps or bulbs are a bad idea near storage shelving, as the heat generated can easily start a fire. Protected incandescent bulbs should be no closer than 12 inches to the shelf space. Fluorescent or recessed lights should be no closer than 6 inches to the shelves. - ANS Conductor Protection: All current-carrying wiring needs some form of protection from mechanical damage. Also, the occupants of the home need protection from potential shocks where wires are spliced together. - ANSExposed Wiring: Obviously, there should be no exposed wiring in the finished or livable areas of the home, but this means that some unfinished areas may have exposed, non-metallic Romex®-type cables. copper: absolutely the best conductor in common use, as it has low electrical impedance, so a relatively small conductor can deliver a lot of power over long distances without too much power loss or heat generation. - ANStinned copper: still sometimes seen on older properties. Copper is tinned for two reasons: to aid soldering; and to stop the copper from reacting with old rubber insulation. Current - ANSIs the flow of electrons driven by electromotive force through a given resistance. This is expressed as amps. = Flow rate= Amps = I Distribution Panels - ANSDistribution panels, or load-side panels, are downstream from the panel containing the main service disconnect(s). In these panels, the neutral and grounds should be separate, and the neutral bus should be isolated from the panel enclosure. The only exception to this is in existing detached structures where no metallic path exists between the structures. Double-tapping is sometimes also called "double taps" or "double-lugging." This is when there are two conductors terminating under a screw or lug which is rated for only one. - ANSAs the neutral is also a current-carrying conductor, the neutrals should each be terminated separately on the neutral bus. An inspector will often find signs of arcing and overheating where any multiple conductors share a common lug. Earth or ground wire - ANSEquipment grounding conductor Edison Base Screw Fuse Panels - ANSThese are the fuses that screw into many older panels and have the same thread that Edison used for other applications, such as the common light bulb. This obviously creates a problem, since a higher-amperage fuse can be screwed into a location supporting lower-amperage conductors, effectively turning the conductor into the fuse. The inspector should recommend the installation of S-type fuses and adapters to ensure that the circuits cannot be overloaded. electrical disconnects require - ANSIt is required that the entire electrical supply to the home be able to be shut off with six or fewer moves of the hand. Electrical power - ANSIs the amount of work that the electrical flow can do. This is expressed as watts or kilowatts (1,000 watts). (W) = E(I) Electrically Heated Floors: To protect people, GFCI protection should be installed at electrically heated floors in bathrooms, kitchens and in hydro-massage bathtub, spa and hot tub locations. 9. 15- and 20-amp receptacles in crawlspaces at or below ground level. - ANSAFCI protection is recommended at 15- and 20-amp outlets on branch circuits for bedrooms, closets, dens, dining rooms, family rooms, hallways, kitchens, laundry areas, libraries, living rooms, parlors, recreation rooms, and sun rooms. Grounding Electrode - ANSMost residential construction requires two separate grounding electrodes in any combination of the following (which need to be at least 6 feet apart): driven rods; 1. metal water pipes; 2. well casings; 3. Ufer grounds - The requirements for Ufer grounds are that they have either 20 feet of #4 rebar, or 4-awg copper wire embedded in at least 2 inches of solid concrete within the footer that is in contact with the earth.; 4. ground plates; 5. steel framing; and 6. ground rings. Gas piping CANNOT be used as a grounding electrode for safety reasons Grounding rod - ANSGrounding Electrode Habitable Spaces: All habitable spaces are required to have electrical power and, in new construction, one would expect to see an outlet at every 12 feet of wall space. Even hallways longer than 10 feet are required to have power. - ANSFloor-Mounted Receptacles: Standard wall-type receptacles pose a danger when mounted horizontally in a floor structure. Dirt, dust and any spilled water will affect the outlet, plus children or pets will always play with anything on the floor. Recommend upgrading floor receptacles to the approved type, with special covers. Hot or live wire - ANSUngrounded conductor how many conductors does a 120/240 service drop have? - ANSon a typical 240/120- volt service drop, we will have two ungrounded conductors and a single grounded conductor. In all 3-phase panels, the conductors are color-coded to identify which phase they are attached to using black, red and blue. While there is no required standard of color coding demanded in the NEC, the code does tell us that on a 120/208 Delta High-Leg system, the center "B" eg (208V to ground) should be marked with orange tape to identify it as the "high leg." - ANS In newer homes' bathrooms, outlets are required to be on dedicated 20-amp, GFCI- protected circuits, and at least one receptacle is required to be installed within 3 feet of any vanity basin. The home inspector is justified in suggesting that non-GFCI receptacles in older bathrooms should be upgraded for safety reasons. - ANSThere must be a minimum of one 20-amp circuit within 6 feet of the appliance location. Dryer outlets will be covered in the 240-volt section, but they should have a 4-wire, 30-amp minimum supply. In the 1999 NEC, these breakers were required only on bedroom receptacles. In the 2002 NEC, they expanded to all 15-amp and 20-amp, single-phase, 120-volt branch circuit-supplying outlets. Finally, in the 2008 NEC, the use of combination-type AFCIs expanded to 15- and 20-ampere branch circuit-supplying outlets installed in a dwelling unit's family room, dining room, living room, parlor, library, den, bedroom, sun room, recreation room, and similar rooms, including hallways and closets. - ANS Inspecting distribution panels - ANS1. How is the service grounded back to the service panel? 2. Are the neutrals and grounds separated? 3. Is the neutral bus isolated from the panel enclosure? 4. Is the panel enclosure connected (bonded) to the grounding bus? 5. Does each neutral conductor terminate at a separate lug on its bus? Inspecting Service Panels - ANS1. Are the neutral and ground connected (bonded)? 2. Is the panel enclosure connected (bonded) to ground? 3. Does each neutral conductor terminate at a separate lug on its bus? Kitchen: To protect people, GFCI protection should be installed at all 125-volt, single-phase, 15- and 20-ampere receptacles that serve countertop surfaces. Sink: To protect people, GFCI protection should be installed at all 125-volt, single-phase, 15- and 20-ampere receptacles that are located within 6 feet of the outside edge of a sink, bathtub or shower. Receptacle outlets shall not be installed in a face-up position in the counter top or work surface. - ANSBoathouse: To protect people, GFCI protection should be installed at all 125-volt, single-phase, 15- or 20-ampere receptacles installed in boathouses. Boat Hoist: To protect people, GFCI protection should be installed for outlets supplying up to 240 volts at boat hoists. Knob-and-tube wiring is so named because of the porcelain fittings used to support and insulate the conductors from the timber components in the home. The knob holds the wire away from rafters and joists, while the tubes are inserted into holes bored though joists and studs to protect the conductor and its rubber insulation. Knob-and-tube wiring was the common method used to wire homes in the United States prior to 1930. - ANSKnob-and-tube is a two-wire system with a hot (ungrounded) and a neutral (grounded conductor) only. No separate ground is used, so all receptacles would have been two-prong only. The home inspector should report any knob-and-tube wiring as in need of further evaluation by an electrical contractor. Main disconnect - ANSService disconnect Main panel - ANSService or distribution electrical board with a service disconnect many faults related to damaged conductors inside the panel are caused by either the wrong screws being used, or the correct screws running up against the live conductors and causing a dead short against the panelboard. - ANS Minimun apms - ANSFor houses serving one family, the ampacity of the ungrounded service conductors shall be a minimum of 100 amperes, 3 wire. For all other installations, the ungrounded conductors should have an ampacity of at least 60 amperes. The ungrounded service conductors should have an ampacity of at least the size of the load served. Most circuits in the modern North American home and light commercial construction are wired with non-metallic sheathed (NM) cable designated type (often referred to by the brand name "Romex"). This type of cable is the least expensive for a given size and is appropriate for dry indoor applications. - ANS Neutral wire - ANSGrounded conductor Newer homes are required to have a minimum of one outlet at the front and another at the rear. These receptacles are required to be weathertight while in use, and GFCI- protected. Non-GFCI outlets are allowed for dedicated single outlets only, such as one will find supplying heater strips in colder climates. - ANSThe inspector should visually inspect a representative number of receptacle outlets and report the following: 1. 2-wire-only circuits; 2. damaged or missing cover plates; 3. missing screws; 4. damaged receptacles; 5. signs of overheating on receptacles or surrounding walls; and 6. lack of GFCIs and AFCIs. Non-Metallic Cable (NM): Many people use the name Romex® when referring to type- NM cable. Romex® is a trademarked name that has come into common usage. The earliest NM cables were, in fact, rubber-insulated copper conductors bound together as an assembly, with a woven-cloth sheathing. In type NM cable, conductor insulation is color-coded for identification, typically one black, one white, and a bare grounding conductor. - ANSOriginally approved by the NEC in 1928 as replacement for knob-and- tube wiring, it became the most common residential wiring used from the late 1940s, up to the introduction of modern thermoplastic (Romex®) type wiring of the early 1960s. Prior to 1985, standard NM was rated for 60-degree applications, which was increased to 90 degrees and is now marked NM-B. Small conductors commonly seen by home inspectors - ANS15 amps = #14 Copper, #12 Aluminium 20 amps = #12 Copper 25 amps = #10 Aluminium 30 amps = #10 Copper, #8 Aluminium Sub-panel - ANSdistribution panel board without a service disconnect the difference between grounding and bonding is: - ANSGrounding is a direct connection to the earth to aid in removing damaging transient over-voltages due to lightning. The purpose of bonding is to ensure the electrical continuity of the fault current path, to provide the capacity and ability to conduct safely any fault current likely to be imposed, and to aid in the operation of the over-current protection device. The home inspector should check the following conditions on a representative number of receptacles: 1. no power present; 2. no ground; 3. open neutral; 4. reversed polarity (hot and neutral); and 5. reversed ground and hot. - ANSThe inspector may also choose to invest in equipment to enable him to report on: 1. low resistance grounds; 2. bootleg grounds; 3. true voltage; and 4. voltage drop. The inspector should also be aware of the concept of the "lit path." One should be able to walk into any home in the dark and be able to go from one room to the next in a lighted path, switching each light off behind as s/he leaves a hall or room. This is for obvious safety reasons, and, as home inspectors are normally inspecting homes in the daylight, checking for safe light is often forgotten. - ANSMany locations are required to have fixed luminaires (lights). These include: 1. kitchens; 2. bathrooms; 3. hallways; 4. staircases; attics; 5. storage spaces; and 6. at exterior doors. The inspector should pay special attention to the following questions and report any deficiencies as in need of immediate repair: - ANS1. Does the breaker exceed the capacity of the conductor? 2. Does the breaker have multiple incorrect "taps"? 3. Do the 240-volt breakers have their handles tied properly? 4. Do the GFCI breakers test and reset properly? 5. Do the AFCI breakers test and reset properly? 6. Is there any sign of overheating, arcing or smoke damage on any of the breakers? The inspector will often see homeowner wiring using things like doorbell or speaker wire, and cut-down extension cords supplying circuits derived from the panel. - ANSAny conductor that has been nicked (cut, scratched, incised, or damaged) as the insulation was removed is now of a smaller diameter than intended and has a higher resistance to the flow of electrons. The minimum size for a listed driven grounding rod is - ANS5/8-inch diameter and 8 feet long stainless steel and copper. The typical electrical service for homes in North America is - ANS120/240 There are many odd receptacle styles out there, but the two that are most common around the home are: 1. dryer outlets: A 240V clothes dryer receptacle has four prongs. The top prong is round and is for the ground connection. The bottom prong is shaped like an "L" and is for the neutral wire. The two vertical slots on the sides are for the two hot wires. - ANS2. range outlets: A 240V oven receptacle also has four prongs, but the neutral prong is straight and not L-shaped. It is, however, narrower and thicker than the hot-wire prongs. These two plugs have four prongs because they use two hot wires to provide the 240- volt power. These receptacles have different designs so that a 30-amp dryer cannot be accidentally connected to a 50-amp range circuit, for example. There is a common misconception that GFCIs work only on grounded circuits. This is not entirely the case. While there are conditions under which the GFCI will not be able to trip without a ground, the inspector should still recommend that any circuits in potentially wet or damp locations be fitted with them as a safety precaution. - ANSBathroom: To protect people, ground-fault circuit interrupter (GFCI) protection should be installed in all bathrooms with 125-volt, single-phase, 15- and 20-ampere receptacles. Laundry: To protect people, ground-fault circuit interrupter (GFCI) protection should be installed in laundry rooms with 125-volt, single-phase, 15- and 20-ampere receptacles. Two-prong receptacles, often found by an inspector in an older home, that are connected to two-wire cables do not have the ground wires, which protect people and electrical devices in case of a fault. It is possible to retrofit a new three-prong or GFCI receptacle into the same receptacle box without any rewiring, as long as the box itself is grounded. - ANSIt is permissible to replace a 2-prong ungrounded outlet with a 3-prong GFCI outlet, but it must be labeled as "GFCI Protected Outlet, No Equipment Ground." Even though there is not a grounding conductor, there is still some protection against shock provided by the GFCI. Voltage - ANS= Pressure = Volts = E warning signs that a panel, box, or the system in general may be compromised, - ANS1. scorch marks on the dead front or the panelboard door, indicating a past or recent arc flash; 2. rust, which indicates past or recent moisture intrusion; 3. missing or open breakers that cannot be confirmed to be de-energized; 4. overloading of the circuits with DIY wiring; 5. uninsulated wiring; 6. excessive dust, dirt and debris inside the panelboard; and/or 7. any signs of water inside, around or below the panelboard, which can lead to shock or electrocution. what 4 categories do circuit breakers fall into? - ANS1. 240v double breakers 2. 120v single breakers 3. AFCI breakers 4. GFCI breakers What is an arc flash - ANSAn arc flash occurs when a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to neutral or ground. An arc flash can have various catalysts, including: 1. excess dust; 2. condensation; 3. corrosion; 4. component failure; 5. faulty system installation; 6. dropping a metal tool, which may cause even a small spark; and/or 7. accidental contact. When dealing with the space behind a corner-mounted sink or counter-mounted cooking unit, the 2008 NEC requires that if such space is less than 18 inches, it is not considered a wall space. If that space is 18 inches or more, it must meet the same spacing requirements previously discussed - ANSMost jurisdictions require dishwashers and waste disposals to be on dedicated circuits. Often, refrigerators are plugged into dedicated outlets, which is allowed by the NEC, to prevent nuisance tripping from installed GFCIs. When evaluating a elecrical supply - ANSwe need to recognize that copper and aluminum conductors are not the same, copper inherently has less resistance to the flow of electrons than aluminum does. For this reason, aluminum conductors are always one to two sizes larger than the equivalent copper one for any given amperage When testing AFCIs, as when testing GFCIs, it is recommended by the manufacturers to use the test function on the breaker. However, this only tests the internal circuit board, rather than emulates any actual fault. - ANSAll habitable spaces are required to have a source of light. What is less commonly understood is that any area used for