above the floor or working platform, unless one of the following applies: Each service disconnecting means shall simultaneously disconnect all ungrounded conductors. A neutral conductor is defined as the conductor connected to the ____ that is intended to carry current under normal conditions. The conductors from the service point to the service disconnecting means are known as service conductors. 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. Notwithstanding the provisions of paragraph (g)(6)(vi) of this section, the following equipment need not be grounded: Tools likely to be used in wet and conductive locations if supplied through an isolating transformer with an ungrounded secondary of not over 50 volts; and. A grounded conductor is a system or circuit conductor that is intentionally grounded. You will have to check the listing of the fuse and fuse holder. Electrical metallic tubing must not be ____. Start your trial now! A group of conductors that fit into one conduit may not fit into another type because the ____ of different types of conduit vary. Oddly enough, you will find the underlying concept in NFPA 70E, Standard for Electrical Safety in the Workplace. The ampere rating of this disconnecting means may not be less than the nameplate current rating of the equipment. Find the preimage of www for the linear transformation. 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. NEC Requirements for Transformers | EC&M A cable assembly's ____ conductor can be used as a switch loop (leg) in single-pole, three-way, and four-way switch installations, even though it is an ungrounded (hot) conductor. A load having the maximum level of current sustained for three hours or more is referred to as a ____ load. Overcurrent devices do not have to be readily accessible if located within anded jacobs k. the connecting means is readily accessible the total of the conceitdees of wood local andards Located at the equipmenl where excess is achieved by the we of poetic ANS: PTS: REF: Definitions 3. However, receptacles of cord- and plug-connected arc welders may have ampere ratings not less than the minimum branch-circuit conductor ampacity. Readily Accessible - Electrical Contractor Magazine Stumped by the Code? . Adding an air intake vent and then adding a fan in the exhaust ducting will make the room more tolerable for both the transformer(s) and the electricians working in that room. 240.6(A)]. 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. The supply systems for sensitive electronic equipment are _______ systems.A. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table S-5; or, where larger than 50 amperes, the receptacle rating may not be less than the branch-circuit rating. 250.12]. LOCATED WITHIN A GROUNDED JUNCTION BOX B. Neutral Conductor or Point A. Ensure the room is vented either via door vents that cannot be blocked or (preferably) an exhaust vent to the outside. Thus, for voltages higher, A: 12. The main bonding jumper is connection at the service between the grounded circuit conductor and the equipment grounding conductor. A transformer must have a disconnect within sight of the transformer unless the disconnect location is field marked on the transformer, and the disconnect is capable of being locked in the open position per Sec. Accessible (Equipment) Accessible equipment is equipment not guarded by locked doors, elevators, or other. The full form of the acronym, MCCB, is Miniature Case. as is. 450.9 provides ventilation requirements, and Sec. maximum fuse or circuit breaker size =, 4.a. 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. 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. So, what does it really cover? Metal car frames supported by metal hoisting cables attached to or running over metal sheaves or drums of grounded elevator machines are also considered to be effectively grounded. , Enclosure Any case, housing, apparatus, fence, or wall surrounding an installation designed to prevent personnel from accidentally contacting energized parts to protect the equipment from physical damage serves as an enclosure. The continuity of the equipment grounding conductor shall be continuously monitored so as to deenergize automatically the high voltage feeder to the portable equipment upon loss of continuity of the equipment grounding conductor. For an ungrounded service-supplied system, the equipment grounding conductor shall be connected to the grounding electrode conductor at the service equipment. (If these areas are accessible to other than pedestrian traffic, then one of the other conditions applies.). C. A single conduit is not permitted as sole support for an FS-type or weatherproof junction box. Branch circuit overcurrent definition | Mike Holt's Forum Over commercial areas subject to truck traffic. That plug-in breaker thing is a piece of utilization equipment. A wire, bus, screw, or similar suitable conductor is acceptable as a main bonding. According to Note 1 of Table 450.3(B), transformers having a primary current rating of 9A or more are permitted to use the next size up rule when 125% of the primary current doesnt correspond to the standard rating of a fuse or nonadjustable circuit breaker listed in Sec. A voltmeter will not register a voltage when connected to the same ungrounded (hot) phase. Both the equipment grounding conductor and the grounding electrode conductor shall be connected to the grounded circuit conductor on the supply side of the service disconnecting means or on the supply side of the system disconnecting means or overcurrent devices if the system is separately derived. Ground-fault detection and relaying shall be provided to automatically deenergize any high voltage system component that has developed a ground fault. If the transformer will be set where forklifts might be present, ensure someone installs the correct protection (such as a bollard set into the floor). Over areas, other than public streets, alleys, roads, and driveways, subject to truck traffic. Then we have: VII. ampacity = Exterior protected locations under canopies, roofs, porches, and similar sites are considered damp locations. See 210. A load having the maximum level of current sustained for three hours or more is referred to as a ____ load. They cant be attached to any fire escape, downspout or plumbing equipment. Nec Flashcards | Quizlet Each service disconnecting means shall be suitable for the prevailing conditions. 225.40 Wiring and Protection, Access to Overcurrent Protective Devices. Signs warning of high voltage shall be posted where unqualified employees might come in contact with live parts. Evaluate the indefinite integrals in this exercise by using the given substitution to reduce the integral to standard form. Using bonding bushes on the ends of the raceway, Four 4 AWG copper conductors with THHN insulation installed in EMT in a basement. A conductor used as a grounded conductor shall be identifiable and distinguishable from all other conductors. four-wire, three-phaseB. 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. Readily Accessible | Mike Holt's Forum 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. Raceway fill calculations are a prerequisite in ____ needed for particular circuits. 1910.306 - Occupational Safety and Health Administration Service A. The conductors are terminated at a through-the-roof raceway or approved support. The given Statment Courtesy ofwww.MikeHolt.com. A fixed or portable optional standby systems, A: Choose the correct option If the circuit\'s overcurrent device exceeds _____, the conductor ampacity shall have a rating not less than the rating of the overcurrent device. Conductors and equipment shall be protected from overcurrent in accordance with their ability to safely conduct current. patient care area.B. just for the sake of argument, if this guy puts an inline fuse at a 'j box'(its above the ceiling) that is just before the receptacle outlet, then is the point from the j box to the out let of the receptacle the 'branch circuit'?? Overcurrent devices do not have to be readily accessible if located within anded jacobs k. the. Therefore, So a telephone occupies a circuit for, A: A circuit breaker is a kind of electrical switch which is used to protect an electrical circuit from, A: A power station is to provide electricity to a huge number of people. 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. f(x)=4x+53. PPSX National Electrical Code 2004 - Quia Cord connections. 4. Circuit breakers and fuses must be readily accessible [240.24]. 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. 1910.304(f)(1)(v) Fuses and circuit breakers shall be so located or shielded that employees will . The secondary conductor ampacity is not less than 1 10 of the rating of the overcurrent device protecting the primary of the transformer multiplied by the turns ratio. The maximum number of conductors applies only if the box does not contain any ____. Service Drop A. This Note does not require the next size up protection; it permits the next size up. Part I contains the general requirements (such as guarding, marking, and accessibility), and Part II contains requirements for specific types of transformers. It may be tempting for some people to use that room as a storage area. Example: Conductors connected to switches and receptacles are accessible by a removable plate or device. Special Permission AHJ Special permission is the written consent of the authority having Jurisdiction or the AHJ who enforce the NEC and grant variances in the code (building department). LOCATED ADJACENT TO THE EQUIPMENT WHERE ACCESS IS ACHIEVED BY THE USE OF PORTABLE MEANS C.THE TOTAL LOAD OF THE ADJACENT CIRCUIT DOES NOT EXCEED LOCAL STANDARDS D.THE DISCONNECTING MEANS IS READILY ACCESSIBLE. Primary Overcurrent Protection = 54A 125% = 68A; use the next size up, 70A [Sec. Exposed noncurrent-carrying metal parts of cord- and plug-connected equipment that may become energized shall be grounded under any of the following conditions: If in hazardous (classified) locations (see 1910.307); If operated at over 150 volts to ground, except for guarded motors and metal frames of electrically heated appliances if the appliance frames are permanently and effectively insulated from ground; If the equipment is of the following types: Refrigerators, freezers, and air conditioners; Clothes-washing, clothes-drying, and dishwashing machines, sump pumps, and electric aquarium equipment; Hand-held motor-operated tools, stationary and fixed motor-operated tools, and light industrial motor-operated tools; Motor-operated appliances of the following types: hedge clippers, lawn mowers, snow blowers, and wet scrubbers; Cord- and plug-connected appliances used in damp or wet locations, or by employees standing on the ground or on metal floors or working inside of metal tanks or boilers; Portable and mobile X-ray and associated equipment; Tools likely to be used in wet and conductive locations; and. A lamp holder itself is not a luminaire. A major concern with transformers is preventing overheating. A compartment or chamber having one or more attached air ducts and forming the distribution system is known as a plenum. One of the most common applications for "readily accessible" occurs in 240.24(A), in which the NEC states that overcurrent devices must be readily accessible and installed so that the center of the grip of the operating handle of the switch or circuit breaker, when in its highest position, is not more than 6 feet, 7 inches above the floor . A circuit breaker with a slash rating, such as 120/240 V or 480Y/277 V, may only be installed in a circuit where the nominal voltage of any conductor to ground does not exceed the lower of the two values of the circuit breaker's voltage rating and the nominal voltage between any two conductors does not exceed the higher value of the circuit breaker's voltage rating. Where a feeder overcurrent device is not readily accessible, branch-circuit overcurrent devices shall be installed on the load side, shall be mounted . The frame of a portable generator need not be grounded and may serve as the grounding electrode for a system supplied by the generator under the following conditions: The generator supplies only equipment mounted on the generator or cord- and plug-connected equipment through receptacles mounted on the generator, or both; and. Receptacle A. 450.9]. A fuse is an electrical gadget used to shield the circuit from overcurrent. But it does not stop there; Sec. 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. Mandatory rules in the NEC contain the language Power conductors below communication conductors -- 762 mm (30 in. Identify each wire with a proper terminal marking, as shown in the example, above the disconnect switch. 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. 5 Key Considerations for Single Family Residential Electrical - NFPA Where a grounding means does not exist in the receptacle enclosure, the installation shall comply with one of the following provisions: A nongrounding-type receptacle may be replaced with another nongrounding-type receptacle; or. A. What are the steps for plotting points on microstation uisng offset, station, side and elevation? Festoon Lighting C. Messenger wire(s), together with insulators is used to support conductors in all span exceeding 40 ft (12 m) in length. Cable tester detects the, A: Materials that allow current to flow through them are called conductors. A duplex receptacle can be supplied by two branch circuits by removing the tab. Primary Conductor = 6 AWG conductor rated 65A at 75C [Sec. Service Point A. Next we will jump to 240.24 Location in or on Premises. Nonmetallic-sheathed cable passing through holes in metal framing must be protected by ____ covering all metal edges. 1910.304 - Occupational Safety and Health Administration Equipment found damaged or defective shall not be used until repaired; The following tests shall be performed on all cord sets and receptacles which are not a part of the permanent wiring of the building or structure, and cord- and plug-connected equipment required to be grounded: All equipment grounding conductors shall be tested for continuity and shall be electrically continuous; Each receptacle and attachment cap or plug shall be tested for correct attachment of the equipment grounding conductor. ." The word luminaire refers to . 240.6(A)], the next higher rating is permitted [Sec. LOCATED ADJACENT TO THE EQUIPMENT WHERE ACCESS IS ACHIEVED BY THE USE OF PORTABLE MEANS, C.THE TOTAL LOAD OF THE ADJACENT CIRCUIT DOES NOT EXCEED LOCAL STANDARDS, D.THE DISCONNECTING MEANS IS READILY ACCESSIBLE. Overcurrent devices shall be readily accessible to each employee or authorized building management personnel. Enclosures are guarded against employee contact. . These circuits exclude the connection of luminaires (lights) unless they are part of the appliance being connected. You are using an out of date browser. Branch Circuits. Answered: Overcurrent devices do not have to be | bartleby Electric Metal Tubing (EMT) provides protection from ____. As long as you can remove the trim and access the junction box it will be considered readily accessible! You can never fix power quality problems by introducing grounding or bonding errors at the transformer or anywhere else. 110.14(C)(1)(a)(3) and Table 310.16]. Open conductors, open multiconductor cables, and service-drop conductors of not over 600 volts, nominal, shall conform to the minimum clearances specified in Table S-6. "must" or "must note penalties for noncompliance" b. shall" or "shall not suggested but discretionary ANS: PTS: Electrical Code REF: The National 10. Overcurrent protection for transformers not over 1,000V. Is this in a room with an inswing door? They can also be installed in panelboards or control boards that are in rooms or enclosures free from dampness, easily ignitable material and accessible only to qualified personnel. Which agency is responsible for the maintenance and publication of the NEC ? All conductors of a multiwire branch circuit must originate from ____. A motor disconnecting means must be located in sight from the motor location as required by 430. Post author: Post published: June 10, 2022; Post category: printable afl fixture 2022; Over commercial areas subject to pedestrian traffic or to vehicular traffic other than truck traffic. It is a system in which exchange the information between two node or points., A: Delay skew is the difference between the propagation delay on the fastest and slowest pairs in a UTP, A: Although, , surrounded by a case, housing, fence, or walls and it prevents people from accidentally contacting energized parts is referred to as enclosed. What is different about table 250.122 versus the other tables we have been using is that it is based on the rating of the overcurrent device, often a circuit breaker of fuse, that is ahead of the circuit that could cause the system to become energized. Code Change Summary: Revised code language on the accessibility requirements for overcurrent devices. Meaning that if you had to get a ladder to reset this breaker, its considered accessible equipment as long as its not blocked. For a grounded system, a grounding electrode conductor shall be used to connect both the equipment grounding conductor and the grounded circuit conductor to the grounding electrode. Never set two transformers with their vents facing each other. Start with "Branch Circuit," not with "Branch Circuit Overprotection Device.". (This category includes conditions covered under the 3.05-m (10.0-ft) category where the voltage exceeds 150 V.). Thus, you do not create a new branch circuit. n the Duplicate Busbar System, continuity of service is possible even if the Main, A: All the exposed noncurrent carrying metal parts of an information technology system shall be bonded, A: Correct option is B that is ELECTRIC GROUND CONDUCTORS must be capable of withstanding the higher, A: Jumpers allow the computer to shut down the electrical circuit, allowing electricity to flow to, A: Question.
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