The NEC.arose as a consensus of more than 1200 individuals primarily to omhat wing spidemic of electrical fires standardize equipment d.standardie price schedules REF: ANS: PTS: Electrical Code The National 7. FLAC NEC Whi MULTIPLE CHOICE 1 Wiring components are considered accessible if(t) access can be gained without damaging the structure or finish of the building or if (2) they are ae Sledstry of the wiring here salatile in the ANS: PTS: 1 REF: Definitions 2. All 3-wire dc systems shall have their neutral conductor grounded; Two-wire dc systems operating at over 50 volts through 300 volts between conductors shall be grounded unless: They supply only industrial equipment in limited areas and are equipped with a ground detector; They are rectifier-derived from an ac system complying with paragraphs (g)(1)(iii), (g)(1)(iv), and (g)(1)(v) of this section; or. The biggest hang up we had was the use of the word "obstacle." Receptacle A. A: The Digital OUT of the first IR Sensor is connected to Pin 11 of Arduino and the Digital OUT of the, A: The convolution theorem is used to convert a time signal into an s-domain signal when multiple, A: As stated by National Electric Code(NEC),the maximum cover of UF cable or the maximum burial depth, A: The circuit is shown below: Festoon Lighting C. Messenger wire(s), together with insulators is used to support conductors in all span exceeding 40 ft (12 m) in length. 240.6(A)]. Power quality problems can occur because of incorrectly grounding and bonding a transformer. four-wire, single-phase. If someone props the door open (for example, because the room is hot and they need to work in there), and the inswing door blocks the vent of a transformer, that transformer is more likely to overheat. Neutral Conductor or Point A. connected to ground or to a conductive body that extends the ground connection. What size primary-only protection overcurrent device and conductor is required for a 45kVA, 3-phase, 480V transformer that is fully loaded? You are using an out of date browser. Ground detectors are installed on the control system; If the system is an isolated power system that supplies circuits in health care facilities; or. Conduit (Junction) Box, Conduit Body B. FS, FD and larger boxes (cast or sheet metal) are not classified as conduit bodies. Note 1 of Table 450.3(B) says that if 125% of the primary current does not correspond to a standard rating of an overcurrent protective device [Sec. main bonding jumper Overcurrent protection for transformers not over 1,000V. overcurrent devices do not have to be readily accessible if. Wire connectors, pigtails, locknuts, bushings, raceway connectors, grounding screws, and equipment bonding jumpers are not factors when calculating ____. You are right, and the other guy is wrong. Overcurrent devices do not have to be readily accessible if ____. Nonconductive coatings on transformer enclosures must be removed to ensure electrical continuity, or the termination fittings must be designed to make such removal unnecessary [Sec. The. An intersystem bonding termination will typically be used as a ground junction for a/anA. tribale maximize ANS: PTS: REF: Definitions 5 A contact device installed at an outlet for the connection of an attachment plug is an) rumpor und Sutlet canale ANS: PTS: REF: Definitions 6. Fitting A. A luminaire that weighs more than ____ pounds shall be supported independently of the outlet box, unless the outlet box is listed and marked for the maximum weight to be supported. Outlet A point in a wiring system from which current is taken to supply utilization equipment is known as an outlet. In Sight A. NEC defines in sight from, within, or within sight to the applied equipment and indicates that specified items or equipment is visible and not more than 50 Ft. apart. The following requirements apply to temporary wiring installations that are used during construction-like activities, including certain maintenance, remodeling, or repair activities, involving buildings, structures or equipment. , surrounded by a case, housing, fence, or walls and it prevents people from accidentally contacting energized parts is referred to as enclosed. A feeder consists of all circuit conductors located between the service equipment, the source of a separately derived system, or other power supply source and the final branchcircuit overcurrent device. Conductors and equipment shall be protected from overcurrent in accordance with their ability to safely conduct current. What are the steps for plotting points on microstation uisng offset, station, side and elevation? Except for motor running overload protection, overcurrent devices may not interrupt the continuity of the grounded conductor unless all conductors of the circuit are opened simultaneously. Grounding Triad is the term which is missing in NATIONAL, A: Eachtelephone makes 0.5 calls/hour at 5 minutes. All 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets that are not part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel. Verified questions. Main panel, Branch Circuit Multi-wire E. There must be only one grounded neutral conductor, and there must be an equal voltage between it and each undergrounded conductor of the circuit. The branch circuit wiring method shall include or provide an equipment grounding conductor to which the grounding contacts of the receptacle or cord connector shall be connected. Plenum (Space) A. Branch Circuit Multi-wire Multi-wire circuit consists of one (or more) duplex receptacles, one or more multiple receptacles single or combination. Clearance from ground. A fixed or portable optional standby systems, A: Choose the correct option T/F. . IMO, if you stick a fuse within a cord, and plug that cord into a receptacle outlet, you are outside the premises wiring system. Overcurrent devices shall be readily accessible to each employee or authorized building management personnel. Conductors: With junction boxes of recessed luminaires can be accessed by removing part of the luminaire. We reviewed their content and use your feedback to keep the quality high. 450.9 provides ventilation requirements, and Sec. Dont install a transformer with the vent facing a distribution panel, cable rack, or other equipment that needs cool air. Accessible (Readily Accessible) Ready accessibility to wiring in luminaires is not required. A. If the door is an inswing type, ensure the opened door will not block the transformer vent. Metal enclosures for service equipment shall be grounded. The terminals are rated 75C (Fig. The grounded circuit (system) conductor is generally not permitted to be used to ground, A: Amotorcontrollerisadeviceorcombinationofdevices,thatcancontrolhowanelectricmotor, A: According to question we have to discuss about A service disconnection means must be installed, A: two types of signaling mode with a neat diagram, A: With industry input, the TIA/EIA cable standards have been developed by the Telecommunications, A: According to article 702 - Optional Standby System Thus, for voltages higher, A: 12. 18. 5. Vertical clearance of final spans above, or within 914 mm (3.0 ft) measured horizontally of, platforms, projections, or surfaces from which they might be reached shall be maintained in accordance with paragraph (c)(2) of this section. The service point is the point of connection between the facilities of the serving utility and the premises wiring. C. THE TOTAL LOAD OF THE ADJACENT CIRCUIT DOES NOT EXCEED LOCAL STANDARDS. The record shall be made available on the jobsite for inspection by the Assistant Secretary and any affected employee. All required tests shall be performed before first use; before equipment is returned to service following any repairs; before equipment is used after any incident which can be reasonably suspected to have caused damage (for example, when a cord set is run over); and at intervals not to exceed 3 months, except that cord sets and receptacles which are fixed and not exposed to damage shall be tested at intervals not exceeding 6 months; The employer shall not make available or permit the use by employees of any equipment which has not met the requirements of paragraph (b)(3)(ii)(C) of this section; and. The maximum number of conductors applies only if the box does not contain any ____. Bonding Jumper (Main) When metal parts are required to be electrically connected, a reliable conductor (Bonding Jumper) is installed, thereby guaranteeing electrical conductivity. 450.13(A) and (B): (A) Open Installations. Example: Conductors connected to switches and receptacles are accessible by a removable plate or device. 2023 Endeavor Business Media, LLC. Cables running horizontally (or diagonally) are considered supported and secured when passing through a(n) ____. Prior to the 2017 NEC, "overcurrent devices" were required to be readily accessible. It may not display this or other websites correctly. Service-entrance conductors installed as open wires shall be guarded to make them accessible only to qualified persons. An outlet intended for the direct connection of a lampholder or luminaire is called a. lighting outlet. the same panelboard or similar distribution equipment. 100]. Alternatively, you can also use a properly rated safety switch. Metal enclosures for conductors added to existing installations of open wire, knob-and-tube wiring, and nonmetallic-sheathed cable need not be grounded if all of the following conditions are met: Runs are less than 7.62 meters (25.0 ft); Enclosures are free from probable contact with ground, grounded metal, metal laths, or other conductive materials; and. Draw clearly, neatly, and properly the Circuit Schematic Diagram for a SINGLE BUSBAR SYSTEM with BUS SECTIONALIZATION. Then we have: VII. 4 A through D for additional requirements. Exception: Overcurrent devices don not have to be readily accessible if located adjacent to the equipment where access is achieved by the use of portable means. Raceway fill calculations are a prerequisite in ____ needed for particular circuits. Cord connections. This prevents the equipment from being readily accessible to people in general and is a good safety measure. NEC identifies ____ types of rigid PVC conduit. You are right, and the other guy is wrong. (B) Suspended Ceilings. equipment grounding terminal bus Overcurrent protection shall not exceed _____. The conductor must be sized to accommodate the 70A primary overcurrent protection per Sec. For fire pumps, conductors may be protected for short circuit only; and. Transformers must be readily accessible to qualified personnel for inspection and maintenance [Sec. That plug-in breaker thing is a piece of utilization equipment. Grounded (grounding) is defined as being ____. Where the ampacity of the ungrounded conductors doesn't correspond with the standard rating of overcurrent protection devices as listed in 240.6(A), you can use the next higher protection device if it doesn't exceed 800A [240.4(B)]. A: The correct option along with the explanation is provided in the following section. 450.14] (Fig. Each service disconnecting means shall simultaneously disconnect all ungrounded conductors. Service Drop A. There are a wide variety of supplementary fuses and fuse holders, which have small physical . An outlet intended for the direct connection of a lamp holder or luminaire is called a lighting outlet. . Overcurrent Protection Device Overcurrent Protection (Breaker) A branch-circuit overcurrent protection is a device capable of protecting feeders, branch circuits, service equipment between its rated current and its interrupting rating. Most supplemental overcurrent protective devices have very low interrupting ratings. Where connected to a branch circuit having a rating in excess of 20 amperes, lampholders shall be of the heavy-duty type. Over public streets, alleys, roads, and driveways. Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and metal outlet or junction boxes that are part of the circuit for these appliances shall be grounded. Lighting Outlets A. In this example, a 70A breaker and 6 AWG conductor will meet Code requirements. Note 2 to paragraph (b)(3)(ii)(A) of this section: Cord sets and devices incorporating the required ground-fault circuit-interrupter that are connected to the receptacle closest to the source of power are acceptable forms of protection. Feeder and branch-circuit conductors shall have overcurrent protection in each ungrounded conductor located at the point where the conductor receives its supply or at a location in the circuit determined under engineering supervision; Circuit breakers used for overcurrent protection of three-phase circuits shall have a minimum of three overcurrent relays operated from three current transformers. A grounding electrode is a(n) ____ object that establishes a direct connection to earth. Readily accessible We recently had a spirited discussion on the job about the term "readily accessible" and what that really means in the NEC. If you stick a fuse in a branch circuit, IMO, you have started a new branch circuit. What is the angle pull for a raceway in the vertical dimension where the trade size of the largest raceway is 4 and the sum of the other raceways in the same row on the same wall is 5? Branch Circuit General Purpose A general purpose branch circuit supplies two or more receptacles or outlets for lighting and appliances. The conductors from the service point to the service disconnecting means are known as service conductors. 70 for switch controlled, Concealed Concealed means rendered inaccessible by the structure of finish of a building Conductors in concealed raceways, even though they become accessible by withdrawing them, are still considered concealed. Service A. Proper transformer selection is an important part of preventing transformers from overheating. 1910.304(f)(1)(v) Fuses and circuit breakers shall be so located or shielded that employees will . Branch Circuit The circuit conductors found between a circuits final overcurrent protective device (breaker) and the circuits outlet is called a branch circuit. 4. Is other equipment in there? A grounded conductor is a system or circuit conductor that is intentionally grounded. A motor disconnecting means must be located in sight from the motor location as required by 430. Accessible (Readily Accessible) Readily accessible means capable of being reached quickly without have to climb or remove obstacles. information technology room.4.b. The requirement for maintaining a vertical clearance of 914 mm (3.0 ft) from the edge of the roof does not apply to the final conductor span, where the conductors are attached to the side of a building. Branch Circuit Individual An individual branch circuit supplies only one piece of utilization equipment. The conductors are terminated at a through-the-roof raceway or approved support. Overcurrent devices shall be readily accessible to each employee or authorized building management personnel. 22. 450.13]. Indicate your answer where indicated. Neutral Conductor or Point B. 1. contiguous. of its overcurrent devices protecting branch circuits of 30A or less, shall have individual protection on the line side not greater than the rating of the . 450.3(B)]. ___ are permitted inside conduit bodies, if the manufacturer durably and legibly marked the cubic inch capacity on the conduit body. Exterior protected locations under canopies, roofs, porches, and similar sites are considered damp locations. This receptacle is fed from a multi-wire branch circuit. Overcurrent devices shall be readily accessible, except for busways (368.17(C)), supplementary overcurrent protection (240.10), overcurrent devices per 225.40 and 230.92, and overcurrent devices located adjacent to the equipment they feed if accessible by portable means - e.g., a ladder. First week only $4.99! Occupational Safety and Health Administration, Outreach Training Program (10- and 30-hour Cards), OSHA Training Institute Education Centers, Severe Storm and Flood Recovery Assistance. neutral ground strap What can installation records be used to determine while servicing equipment?A. Using an approved polyvinyl chloride conduitC. In most cases, access can be gained through the use of a ladder or scaffolding ect. This test record shall identify each receptacle, cord set, and cord- and plug-connected equipment that passed the test and shall indicate the last date it was tested or the interval for which it was tested. The neutral point is the midpoint on a single-phase portion of a 3 wire system. Which of the following would help avoid the choke effect in grounding electrode conductors?A. The equipment grounding conductor shall be connected to its proper terminal; and. However, receptacles of cord- and plug-connected arc welders may have ampere ratings not less than the minimum branch-circuit conductor ampacity. ); Power conductors alone or above communication conductors: Communication conductors below power conductors -- same as power conductors; and. To catch up on Lorenzo Mari's series on Overcurrent Protection, please visit: National Electrical Code Basics: Overcurrent Protection Part 1 . They are fire-alarm circuits having a maximum current of 0.030 amperes; AC circuits of less than 50 volts shall be grounded if they are installed as overhead conductors outside of buildings or if they are supplied by transformers and the transformer primary supply system is ungrounded or exceeds 150 volts to ground; AC systems of 50 volts to 1000 volts shall be grounded under any of the following conditions, unless exempted by paragraph (g)(1)(v) of this section: If the system can be so grounded that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts; If the system is nominally rated three-phase, four-wire wye connected in which the neutral is used as a circuit conductor; If the system is nominally rated three-phase, four-wire delta connected in which the midpoint of one phase is used as a circuit conductor; or. Branch Circuit Multi-wire C. Each multi-wire branch circuit must be provided with a means that will simultaneously disconnects all ungrounded (hot) conductors at the point where branch circuits originate. A listener nearby in a 20^ {\circ} \mathrm {C} 20C room hears a note with a wavelength of 40 cm. I dont like the 'new definition' of 'Branch circuit overcurrent device'. 28(7x2)5dx,u=7x2, A(n) ____ is a device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing. The overcurrent devices shall be readily accessible to the tenants they serve -- at anytime the tenant will be able to access the OCD quickley, without hinderance of locked doors in which they do not have keys -- If the tenant can freely walk to the OCD for access then you are good -- I am also assuming the tenant has permanate provisions for cooking in their unit. Over commercial areas subject to truck traffic. Dont install a transformer below a water heater that is on a mezzanine or similar elevation. A load having the maximum level of current sustained for three hours or more is referred to as a ____ load. Article 450 of the National Electrical Code (NEC) opens by saying, This article covers the installation of all transformers. Then it lists eight exceptions. You can never fix power quality problems by introducing grounding or bonding errors at the transformer or anywhere else. If the system is a high-impedance grounded neutral system in which a grounding impedance, usually a resistor, limits the ground-fault current to a low value for 3-phase ac systems of 480 volts to 1000 volts provided all of the following conditions are met: Ground detectors are installed on the system; and. Generally, ungrounded (hot) conductors can be any color except ____. overcurrent devices do not have to be readily accessible if. They cant be attached to any fire escape, downspout or plumbing equipment. A lamp holder itself is not a luminaire. An ____ is the organization, office, or individual responsible for enforcing the requirements of a code. Notwithstanding the provisions of paragraph (g)(6)(iv) of this section, exposed noncurrent-carrying metal parts of the following types of fixed equipment need not be grounded: Enclosures for switches or circuit breakers used for other than service equipment and accessible to qualified persons only; Electrically heated appliances that are permanently and effectively insulated from ground; Distribution apparatus, such as transformer and capacitor cases, mounted on wooden poles, at a height exceeding 2.44 m (8.0 ft) above ground or grade level; and. LOCATED WITHIN A GROUNDED JUNCTION BOX B. A (n) ______ is a complete lighting unit consisting of a light. The neutral point is the common point on a Wye-connection in a polyphase system. However, a current-limiting device without a disconnecting means is permitted on the supply side of the service disconnecting means. source such as a lamp or lamps, together with the parts designed to position the light source and to connect it to the power supply. Note 1 to paragraph (b)(3)(ii)(A) of this section: A cord connector on an extension cord set is considered to be a receptacle outlet if the cord set is used for temporary electric power. A disconnecting means shall be provided on the supply side of all fuses in circuits over 150 volts to ground and cartridge fuses in circuits of any voltage where accessible to other than qualified persons so that each individual circuit containing fuses can be independently disconnected from the source of power. B. neutral disconnect link, 18. Listed equipment protected by a system of double insulation, or its equivalent, and distinctively marked as such. Signs warning of high voltage shall be posted where unqualified employees might come in contact with live parts. termination. In addition, a single disconnecting means is permitted on the supply side of more than one set of fuses as permitted by the exception in 1910.305(j)(4)(vi) for group operation of motors, and a single disconnecting means is permitted for fixed electric space-heating equipment. Patient equipment grounding point is used ,to the eliminate the electromagnetic, The compensation techniques are the methods that are employed in the electrical control systems to enhance the performance of the system. (This category includes conditions covered under the 3.05-m (10.0-ft) category where the voltage exceeds 300 V.). A contact device installed at an outlet for the connection of an attachment plug is a receptacle. Neutral Conductor or Point C. The neutral point is the midpoint on a single-phase portion of a 3 phase Delta System. Exposed noncurrent-carrying metal parts of fixed equipment that may become energized shall be grounded under any of the following conditions: If within 2.44 m (8 ft) vertically or 1.52 m (5 ft) horizontally of ground or grounded metal objects and subject to employee contact; If located in a wet or damp location and not isolated; If supplied by a metal-clad, metal-sheathed, or grounded metal raceway wiring method; or. So you cannot plug this appliance into a receptacle outlet that is fed from a 20 amp branch circuit, because their is a protective limit marked on the appliance. The service disconnecting means shall plainly indicate whether it is in the open or closed position and shall be installed at a readily accessible location nearest the point of entrance of the service-entrance conductors. Show FS boxes in Material PDF FS (Ferris Box Standard) FSS (Ferris Box Continuous), Continuous Load A load having the maximum level of current sustained for three hours or more is referred to as a continuous load. A surface, flush, or freestanding raceway designed to hold conductors and receptacles (in the field or the factory). These materials are provided by Mike Holt Enterprises in Leesburg, Fla. To view Code training materials offered by this company, visit www.mikeholt.com/code. A circuit breaker with a straight voltage rating, such as 240 V or 480 V, may only be installed in a circuit in which the nominal voltage between any two conductors does not exceed the circuit breaker's voltage rating. For a better experience, please enable JavaScript in your browser before proceeding. ampacity = Thus, you do not create a new branch circuit. According to the definition of a branch circuit, it starts at the final overcurrent protection device. I would only agree if the fuse were within the premises wiring system. Use and identification of grounded and grounding conductors -, A nongrounding-type receptacle may be replaced with a ground-fault circuit-interrupter-type of receptacle that is marked "No Equipment Ground;" an equipment grounding conductor may not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle; or. Many inline fuses are not suitable for use as a branch circuit OCPD. Select one: Overcurrent devices do not have to be readily accessible if ____. Lets show how this all works through an example problem. . An AFCI is basically like a GFCI but it will protect the entire circuit from the breaker and back. Nonmetallic-sheathed cable not fastened to the box must be secured within ____ in. B. Holes must be bored so that the edge of the hole is at least ____. If a vented dry-type transformer is installed in an equipment room with a door: A terminal bar for equipment grounding conductors (EGCs), system bonding jumpers, supply-side bonding jumpers, and grounding electrode conductors (GECs) must be installed and bonded inside the transformer enclosure [Sec. Enclosures are guarded against employee contact. Over residential property and driveways. Based on the 2020 NEC. Communications conductors alone -- no requirement. Basically, ______receptacles are required to be installed if an equipment grounding conductor is available at the outlet where the receptacle is located. Hrone dans la guerre de 100 ans (100 years war). For each given ppp-series, identify ppp and determine whether the series converges.
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