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x I provides information on the tightening torques from UL 468A-486B, Wire Connectors. These tables should be used for guidance only if no tightening information on a specific wire connector is available. They should not be used to replace the manufacturer’s instructions, which should always be foll...

x I provides information on the tightening torques from UL 468A-486B, Wire Connectors. These tables should be used for guidance only if no tightening information on a specific wire connector is available. They should not be used to replace the manufacturer’s instructions, which should always be followed. UL 486A-486B refers to conductor stranding by class. Terminals and connectors for conductors that are more finely stranded than Class B and C stranding are required to be identified for the class or classes of conductor stranding and the number of strands. Table 10 in Chapter 9 provides information for the application of this information in the field. 110.15 High-Leg Marking. On a 4-wire, delta-connected system where the midpoint of one phase winding is grounded, only the conductor or busbar having the higher phase voltage to ground shall be durably and permanently marked by an outer finish that is orange in color or by other effective means. Such identification shall be placed at each point on the system where a connection is made if the grounded conductor is also present. ENHANCED CONTENT Collapse The high leg is common on a 240/120-volt, 3-phase, 4-wire delta system. It is typically designated as “B phase.” The high-leg marking, which is required to be the color orange or other similar effective means, is intended to prevent problems caused by the lack of standardization where metered and nonmetered equipment are installed in the same installation. See the exhibit below. Electricians should always test each phase relative to ground with suitable equipment to determine exactly where the high leg is located within the system. 110.16 Arc-Flash Hazard Warning. (A) General. Electrical equipment, such as switchboards, switchgear, enclosed panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment. ENHANCED CONTENT Collapse Proper warning labels raise the level of awareness of electrical arc-flash hazards and decrease the number of accidents that result when electricians do not wear the proper type of protective clothing while working on “hot” (energized) equipment. The exhibit below is one example of an equipment warning sign as required by this section. (Courtesy of the International Association of Electrical Inspectors) How to choose suitable personal protective equipment (PPE) appropriate to a particular hazard is described in NFPA 70E, Standard for Electrical Safety in the Workplace. A worker clothed in PPE appropriate for the hazard involved is shown below. (Courtesy of Enespro) Accident reports confirm the fact that workers responsible for the installation or maintenance of electrical equipment often do not establish an electrically safe working condition, as described in NFPA 70E, before working on the equipment. Working on electrical equipment that is energized is a major safety concern in the electrical industry. This requirement alerts electrical contractors, electricians, facility owners and managers, and other interested parties to some of the hazards present when personnel are exposed to energized electrical conductors or circuit parts. It emphasizes the importance of turning off the power before working on electrical circuits. This section does not apply to equipment in dwelling units. However, multifamily dwellings, which include multiple dwelling units, could have the same electric service as a commercial office building. The intent is to provide warnings to electricians working on these larger services. (B) Service Equipment and Feeder Supplied Equipment. In other than dwelling units, in addition to the requirements in 110.16(A), a permanent arc flash label shall be field or factory applied to service equipment and feeder supplied equipment rated 1000 amperes or more. The arc flash label shall be in accordance with applicable industry practice and include the date the label was applied. The label shall meet the requirements of 110.21(B). Informational Note No. 1: See ANSI Z535.4-2011 (R2017), Product Safety Signs and Labels, for guidelines for the design of safety signs and labels for application to products. Informational Note No. 2: See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for applicable industry practices for equipment labeling. This standard provides specific criteria for developing arc-flash labels for equipment that provides nominal system voltage, incident energy levels, arc-flash boundaries, minimum required levels of personal protective equipment, and so forth. ENHANCED CONTENT Collapse The available short-circuit current must be known at the time of installation to comply with the interrupting requirements of 110.9 and 110.10. This information is necessary to determine the incident energy and working distance for compliance with NFPA 70E for future work on the service equipment. Section 110.16(B) specifies the information that a label is required to provide. The date that the label was applied is important because, over time, available fault current can change. Two different arc flash labels meeting the requirements of 130.5(H) of NFPA 70E are shown below. On the left, the label provides the available incident energy and working distance. On the right, the label provides the arc flash PPE category. (Image on the right is courtesy of Graphic Products, Inc.) 110.17 Servicing and Maintenance of Equipment. Servicing and electrical preventive maintenance shall be performed by qualified persons trained in servicing and maintenance of equipment and shall comply with the following: * (1) The servicing and electrical preventive maintenance shall be performed in accordance with the original equipment manufacturer’s instructions and information included in the listing information, applicable industry standards, or as approved by the authority having jurisdiction. * (2) The servicing and electrical preventive maintenance shall be performed using identified replacement parts that are verified under applicable product standards. The replacement parts shall comply with at least one of the following: o a. Be provided by the original equipment manufacturer o b. Be designed by an engineer experienced in the design of replacement parts for the type of equipment being serviced or maintained o c. Be approved by the authority having jurisdiction Informational Note No. 1: For equipment that is not listed or field labeled, or for which components are no longer available from the original equipment manufacturer, one way to determine suitability is to review the documentation that accompanies the replacement parts. Informational Note No. 2: See NFPA 70B, Recommended Practice for Electrical Equipment Maintenance, for information related to preventive maintenance for electrical, electronic, and communication systems and equipment. 110.18 Arcing Parts. Parts of electrical equipment that in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from all combustible material. ENHANCED CONTENT Collapse Examples of electrical equipment that can produce sparks during ordinary operation include open motors that have centrifugal starting switches, open motors with commutators, and collector rings. Adequate separation from combustible material is essential if open motors with those features are used. 110.19 Light and Power from Railway Conductors. Circuits for lighting and power shall not be connected to any system that contains trolley wires with a ground return. Exception: Such circuit connections shall be permitted in car houses, power houses, or passenger and freight stations operated in connection with electric railways. 110.20 Reconditioned Equipment. Reconditioned equipment shall be permitted except where prohibited elsewhere in this Code. Equipment that is restored to operating condition shall be reconditioned with identified replacement parts, verified under applicable standards, that are either provided by the original equipment manufacturer or that are designed by an engineer experienced in the design of replacement parts for the type of equipment being reconditioned. (A) Equipment Required to Be Listed. Equipment that is reconditioned and required by this Code to be listed shall be listed or field labeled as reconditioned using available instructions from the original equipment manufacturer. (B) Equipment Not Required to Be Listed. Equipment that is reconditioned and not required by this Code to be listed shall comply with one of the following: * (1) Be listed or field labeled as reconditioned * (2) Have the reconditioning performed in accordance with the original equipment manufacturer instructions (C) Approved Equipment. If the options specified in 110.20(A) or (B) are not available, the authority having jurisdiction shall be permitted to approve reconditioned equipment, and the reconditioner shall provide the authority having jurisdiction with documentation of the changes to the product. 110.21 Marking. (A) Equipment Markings. (1) General. The manufacturer’s name, trademark, or other descriptive marking by which the organization responsible for the product can be identified shall be applied or affixed onto all electrical equipment. Other markings that indicate voltage, current, wattage, or other ratings shall be provided as specified elsewhere in this Code. The marking shall be of sufficient durability to withstand the environment involved. ENHANCED CONTENT Collapse Below is an example of a short-circuit current rating marking. (Courtesy of Eaton) (2) Reconditioned Equipment. Reconditioned equipment shall be marked with the following: * (1) Name, trademark, or other descriptive marking of the organization that performed the reconditioning * (2) The date of the reconditioning * (3) The term reconditioned or other approved wording or symbol indicating that the equipment has been reconditioned The original listing mark shall be removed or made permanently illegible. The equipment nameplate shall not be required to be removed or made permanently illegible, only the part of the nameplate that includes the listing mark, if applicable. Approval of the reconditioned equipment shall not be based solely on the equi?pment’s original listing. Exception: In industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the equipment, the markings indicated in 110.21(A)(2) shall not be required for equipment that is reconditioned by the owner or operator as part of a regular equipment maintenance program. Informational Note No. 1: ANSI-approved standards are available for application of reconditioned and refurbished equipment. Informational Note No. 2: The term reconditioned may be interchangeable with the terms rebuilt, refurbished, or remanufactured even though these are sometimes different processes. (B) Field-Applied Hazard Markings. Where caution, warning, or danger hazard markings such as labels or signs are required by this Code, the markings shall meet the following requirements: * (1) The marking shall be of sufficient durability to withstand the environment involved and warn of the hazards using effective words, colors, symbols, or any combination thereof. Informational Note No. 1: See ANSI Z535.2-2011 (R2017), Environmental and Facility Safety Signs, which describes the design, application, and use of safety signs in facilities and in the environment. Informational Note No. 2: See ANSI Z535.4-2011 (R2017), Product Safety Signs and Labels, which details the design, application, use, and placement of safety signs and labels on a wide variety of products. * (2) The marking shall be permanently affixed to the equipment or wiring method and shall not be handwritten. Exception to (2): Portions of the markings that are variable, or that could be subject to changes, shall be permitted to be handwritten and shall be legible. 110.22 Identification of Disconnecting Means. (A) General. Each disconnecting means shall be legibly marked to indicate its purpose unless located and arranged so the purpose is evident. In other than one- or two-family dwellings, the marking shall include the identification and location of the circuit source that supplies the disconnecting means unless located and arranged so the identification and location of the circuit source is evident. The marking shall be of sufficient durability to withstand the environment involved. ENHANCED CONTENT Collapse Marking of disconnecting means must specifically identify the purpose of each piece of equipment - that is, the marking should not, for example, indicate simply “motor” but rather “motor, water pump,” or not simply “lights” but rather “lights, front lobby.” The markings must remain legible and not fade or wear off. See also 408.4 and its enhanced content for additional requirements and information on circuit directories for switchboards and panelboards. (B) Engineered Series Combination Systems. Equipment enclosures for circuit breakers or fuses applied in compliance with series combination ratings selected under engineering supervision in accordance with 240.86(A) shall be legibly marked in the field as directed by the engineer to indicate the equipment has been applied with a series combination rating. The marking shall meet the requirements in 110.21(B) and shall be readily visible and state the following: CAUTION - ENGINEERED SERIES COMBINATION SYSTEM RATED _______ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED. ENHANCED CONTENT Collapse The warnings on replacement components are important to follow in order to maintain the level of protection provided by the design. Likewise, when components are replaced, new or updated warning labels with information based on the new component may be necessary. (C) Tested Series Combination Systems. Equipment enclosures for circuit breakers or fuses applied in compliance with the series combination ratings marked on the equipment by the manufacturer in accordance with 240.86(B) shall be legibly marked in the field to indicate the equipment has been applied with a series combination rating. The marking shall meet the requirements in 110.21(B) and shall be readily visible and state the following: CAUTION - SERIES COMBINATION SYSTEM RATED ____ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED. Informational Note: See IEEE 3004.5-2014 Recommended Practice for the Application of Low-Voltage Circuit Breakers in Industrial and Commercial Power Systems, for further information on series tested systems. 110.23 Current Transformers. Unused current transformers associated with potentially energized circuits shall be short-circuited. 110.24 Available Fault Current. (A) Field Marking. Service equipment at other than dwelling units shall be legibly marked in the field with the available fault current. The field marking(s) shall include the date the fault-current calculation was performed and be of sufficient durability to withstand the environment involved. The calculation shall be documented and made available to those authorized to design, install, inspect, maintain, or operate the system. Informational Note No. 1: See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for assistance in determining the severity of potential exposure, planning safe work practices, and selecting personal protective equipment. The available fault-current marking(s) addressed in 110.24 is related to required short-circuit current and interrupting ratings of equipment. Informational Note No. 2: Values of available fault current for use in determining appropriate minimum short- circuit current and interrupting ratings of service equipment are available from electric utilities in published or other forms. (B) Modifications. When modifications to the electrical installation occur that affect the available fault current at the service, the available fault current shall be verified or recalculated as necessary to ensure the service equipment ratings are sufficient for the available fault current at the line terminals of the equipment. The required field marking(s) in 110.24(A) shall be adjusted to reflect the new level of available fault current. Exception: The field marking requirements in 110.24(A) and 110.24(B) shall not be required in industrial installations where conditions of maintenance and supervision ensure that only qualified persons service the equipment. ENHANCED CONTENT Collapse To be used safely, equipment must have an interrupting rating or short-circuit current rating equal to or greater than the available fault current. Any equipment operating with ratings less than the available fault current is potentially unsafe. Existing electrical distribution systems often experience change over the life of the system. As the system ages, the supply network to which it is connected is affected by growth and is forced to increase capacity or increase efficiency by reducing transformer impedance. In some cases, alternative energy systems are added to existing installations. Such changes to the electrical distribution system can result in an increase of the available fault current. That increase in available fault current can exceed the ratings of the originally installed equipment, violating 110.10 and 110.11 and creating an unsafe condition. This section requires an initial marking of maximum available fault current as well as the requirement to update the information when the system is modified. The available fault current must be known to complete an arc-flash risk assessment per Section 130.5 of NFPA 70E, Standard for Electrical Safety in the Workplace. This assessment is used to determine the arc-flash protection boundary and required PPE in accordance with NFPA 70E, Sections 130.5(E) and 130.5(F). The equipment must then be marked with the incident energy or required level of PPE per 130.5(H). According to Article 130 of NFPA 70E, an arc-flash risk assessment is required to be conducted any time work is performed where electrical conductors or circuit parts operate at 50 volts and greater and are not placed in an electrically safe work condition. Additionally, per 130.5(H) of NFPA 70E, the assessment must be reviewed periodically - at least every 5 years - to account for changes in the electrical distribution system that could affect the original arc-flash assessment. 110.25 Lockable Disconnecting Means. If a disconnecting means is required to be lockable open elsewhere in this Code, it shall be capable of being locked in the open position. The provisions for locking shall remain in place with or without the lock installed. Exception: Locking provisions for a cord-and-plug connection shall not be required to remain in place without the lock installed. ENHANCED CONTENT Collapse The means to lock the switch or circuit breaker in the open position must be an integral part of the enclosure or be an accessory that is not readily removed from the switch or circuit breaker. Portable locking mechanisms that are intended for temporary applications are not acceptable means of compliance. Part II. 1000 Volts, Nominal, or Less 110.26 Spaces About Electrical Equipment. Working space, and access to and egress from working space, shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment. Open equipment doors shall not impede access to and egress from the working space. Access or egress is impeded if one or more simultaneously opened equipment doors restrict working space access to be less than 610 mm (24 in.) wide and 2.0 m (61/2 ft) high. ENHANCED CONTENT Collapse Spaces about electrical equipment are divided into two separate and distinct categories: working space and dedicated equipment space. The term working space generally applies to the protection of the worker, and dedicated equipment space applies to the space reserved for future access to electrical equipment and to protection of the equipment from intrusion by nonelectrical equipment. Storage of material that blocks access or prevents safe work practices must always be avoided. The performance requirements for all spaces about electrical equipment are set forth in this section. (A) Working Space. Working space for equipment operating at 1000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (A)(2), (A)(3), and (A)(4) or as required or permitted elsewhere in this Code. Informational Note: See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for guidance, such as determining severity of potential exposure, planning safe work practices including establishing an electrically safe work condition, arc flash labeling, and selecting personal protective equipment. ENHANCED CONTENT Collapse The intent is to provide enough space for the performance of any of the operations listed without jeopardizing workers. Minimum working clearances are not required if the equipment is not likely to require examination, adjustment, servicing, or maintenance while energized. However, access and working space are still required by the opening paragraph of 110.26. Examples of such equipment include panelboards, switches, circuit breakers, controllers, and controls on heating and air-conditioning equipment. Note that the word “examination” includes tasks such as checking for the presence of voltage using a portable voltmeter. (1) Depth of Working Space. The depth of the working space in the direction of live parts shall not be less than that specified in Table 110.26(A)(1) unless the requirements of 110.26(A)(1)(a), (A)(1)(b), or (A)(1)(c) are met. Distances shall be measured from the exposed live parts or from the enclosure or opening if the live parts are enclosed. Table 110.26(A)(1) Working Spaces Nominal Voltage to Ground Minimum Clear Distance Condition 1 Condition 2 Condition 3 0-150 900 mm (3 ft) 900 mm (3 ft) 900 mm (3 ft) 151-600 900 mm (3 ft) 1.0 m (3 ft 6 in.) 1.2 m (4 ft) 601-1000 900 mm (3 ft) 1.2 m (4 ft) 1.5 m (5 ft) Note: Where the conditions are as follows: Condition 1 - Exposed live parts on one side of the working space and no live or grounded parts on the other side of the working space, or exposed live parts on both sides of the working space that are effectively guarded by insulating materials. Condition 2 - Exposed live parts on one side of the working space and grounded parts on the other side of the working space. Concrete, brick, or tile walls shall be considered as grounded. Condition 3 - Exposed live parts on both sides of the working space. * (a) Dead-Front Assemblies. Working space shall not be required in the back or sides of assemblies, such as dead-front switchboards, switchgear, or motor control centers, where all connections and all renewable or adjustable parts, such as fuses or switches, are accessible from locations other than the back or sides. Where rear access is required to work on nonelectrical parts on the back of enclosed equipment, a minimum horizontal working space of 762 mm (30 in.) shall be provided. * (b) Low Voltage. By special permission, smaller working spaces shall be permitted where all exposed live parts operate at not greater than 30 volts rms, 42 volts peak, or 60 volts dc. * (c) Existing Buildings. In existing buildings where electrical equipment is being replaced, Condition 2 working clearance shall be permitted between dead-front switchboards, switchgear, enclosed panelboards, or motor control centers located across the aisle from each other where conditions of maintenance and supervision ensure that written procedures have been adopted to prohibit equipment on both sides of the aisle from being open at the same time and qualified persons who are authorized will service t