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ow illustrates an installation of festoon lighting that complies with the minimum clearance above-grade requirement specified in 225.18(1). The maximum distance between conductor supports is 40 feet unless a messenger wire is installed to support the current-carrying conductors. Attachment of festoo...

ow illustrates an installation of festoon lighting that complies with the minimum clearance above-grade requirement specified in 225.18(1). The maximum distance between conductor supports is 40 feet unless a messenger wire is installed to support the current-carrying conductors. Attachment of festoon lighting to fire escapes, plumbing equipment, or metal drain spouts is prohibited, because the attachment could provide a path to ground. Such methods of attachment could not be relied on for a permanent or secure means of support. 225.10 Wiring on Buildings (or Other Structures). The installation of outside wiring on surfaces of buildings (or other structures) shall be permitted for circuits not exceeding 1000 volts, nominal, as the following: * (1) Auxiliary gutters * (2) Busways * (3) Cable trays * (4) Cablebus * (5) Electrical metallic tubing (EMT) * (6) Flexible metal conduit (FMC) * (7) Intermediate metal conduit (IMC) * (8) Liquidtight flexible metal conduit (LFMC) * (9) Liquidtight flexible nonmetallic conduit (LFNC) * (10) Messenger-supported wiring * (11) Open wiring on insulators * (12) Reinforced thermosetting resin conduit (RTRC) * (13) Rigid metal conduit (RMC) * (14) Rigid polyvinyl chloride conduit (PVC) * (15) Type MC cable * (16) Type MI cable * (17) Type SE cable * (18) Type TC-ER cable * (19) Type UF cable * (20) Wireways 225.11 Feeder and Branch-Circuit Conductors Entering, Exiting, or Attached to Buildings or Structures. Feeder and branch-circuit conductors entering or exiting buildings or structures shall be installed in accordance with 230.52. Overhead branch circuits and feeders attached to buildings or structures shall be installed in accordance with 230.54. 225.12 Open-Conductor Supports. Open conductors shall be supported on knobs, racks, brackets, or strain insulators, that are made of glass, porcelain, or other approved materials. 225.14 Open-Conductor Spacings. Conductors shall comply with the spacings provided in Table 230.51(C). (A) Separation from Other Circuits. Open conductors shall be separated from open conductors of other circuits or systems by not less than 100 mm (4 in.). (B) Conductors on Poles. Conductors on poles shall have a separation of not less than 300 mm (1 ft) where not placed on racks or brackets. Conductors supported on poles shall provide a horizontal climbing space not less than the following: * (1) Power conductors below communications conductors - 750 mm (30 in.) * (2) Power conductors alone or above communications conductors: o a. 300 volts or less - 600 mm (24 in.) o b. Over 300 volts - 750 mm (30 in.) * (3) Communications conductors below power conductors - same as power conductors * (4) Communications conductors alone - no requirement ENHANCED CONTENT Collapse Sufficient space is required for personnel to be able to climb safely over or through conductors to work with conductors on the pole. 225.15 Supports over Buildings. Outside branch-circuit and feeder conductors passing over a building shall be securely supported. 225.16 Attachment to Buildings. (A) Point of Attachment. The point of attachment to a building shall be in accordance with 230.26. (B) Means of Attachment. The means of attachment to a building shall be in accordance with 230.27. 225.17 Masts as Supports. Only feeder or branch-circuit conductors specified within this section shall be permitted to be attached to the feeder and/or branch-circuit mast. Masts used for the support of final spans of feeders or branch circuits shall be installed in accordance with 225.17(A) and (B). ENHANCED CONTENT Collapse Conductors that are attached to the exterior of the mast are not permitted to be attached between the weatherhead and any coupling that is above a point of securement to the building. Attaching conductors in that space can put additional strain on the mast, which could cause it to fail. A mast supporting an overhead branch circuit or feeder span is not permitted to support conductors of other systems, such as overhead conductor spans for signaling, communications, or CATV systems. See also 230.28, which provides similar requirements for masts supporting service drops. (A) Strength. The mast shall have adequate strength or be supported by braces or guy wires to safely withstand the strain imposed by the overhead feeder or branch-circuit conductors. Hubs intended for use with a conduit serving as a mast for support of feeder or branch-circuit conductors shall be identified for use with a mast. (B) Attachment. Feeder and/or branch-circuit conductors shall not be attached to a mast where the connection is between a weatherhead or the end of the conduit and a coupling where the coupling is located above the last point of securement to the building or other structure, or where the coupling is located above the building or other structure. 225.18 Clearance for Overhead Conductors and Cables. Overhead spans of open conductors and open multiconductor cables of not over 1000 volts, nominal, shall have a clearance of not less than the following: * (1) 3.0 m (10 ft) - above finished grade, sidewalks, or from any platform or projection that will permit personal contact where the voltage does not exceed 150 volts to ground and accessible to pedestrians only * (2) 3.7 m (12 ft) - over residential property and driveways, and those commercial areas not subject to truck traffic where the voltage does not exceed 300 volts to ground * (3) 4.5 m (15 ft) - for those areas listed in the 3.7 m (12 ft) classification where the voltage exceeds 300 volts to ground * (4) 5.5 m (18 ft) - over public streets, alleys, roads, parking areas subject to truck traffic, driveways on other than residential property, and other land traversed by vehicles, such as cultivated, grazing, forest, and orchard * (5) 7.5 m (241/2 ft) - over track rails of railroads ENHANCED CONTENT Collapse This section covers the requirements for clearances from ground; 225.19 covers the requirements for clearances from buildings for conductors not over 1000 volts. Section 225.19(D) provides final span clearances from windows, doors, fire escapes, and similar areas where overhead conductors are subject to contact by persons. The exhibit below shows an example of where those clearance requirements apply. 225.19 Clearances from Buildings for Conductors of Not over 1000 Volts, Nominal. Overhead spans of open conductors and open multiconductor cables shall comply with 225.19(A), (B), (C), and (D). (A) Above Roofs. Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 2.6 m (8 ft 6 in.) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance not less than 900 mm (3 ft) in all directions from the edge of the roof. Exception No. 1: The area above a roof surface subject to pedestrian or vehicular traffic shall have a vertical clearance from the roof surface in accordance with the clearance requirements of 225.18. Exception No. 2: Where the voltage between conductors does not exceed 300, and the roof has a slope of 100 mm in 300 mm (4 in. in 12 in.) or greater, a reduction in clearance to 900 mm (3 ft) shall be permitted. Exception No. 3: Where the voltage between conductors does not exceed 300, a reduction in clearance above only the overhanging portion of the roof to not less than 450 mm (18 in.) shall be permitted if (1) not more than 1.8 m (6 ft) of the conductors, 1.2 m (4 ft) horizontally, pass above the roof overhang, and (2) they are terminated at a through-the-roof raceway or approved support. Exception No. 4: The requirement for maintaining the vertical clearance 900 mm (3 ft) from the edge of the roof shall not apply to the final conductor span where the conductors are attached to the side of a building. (B) From Nonbuilding or Nonbridge Structures. From signs, chimneys, radio and television antennas, tanks, and other nonbuilding or nonbridge structures, clearances - vertical, diagonal, and horizontal - shall not be less than 900 mm (3 ft). (C) Horizontal Clearances. Clearances shall not be less than 900 mm (3 ft). (D) Final Spans. Final spans of feeders or branch circuits shall comply with 225.19(D)(1), (D)(2), and (D)(3). (1) Clearance from Windows. Final spans to the building they supply, or from which they are fed, shall be permitted to be attached to the building, but they shall be kept not less than 900 mm (3 ft) from windows that are designed to be opened, and from doors, porches, balconies, ladders, stairs, fire escapes, or similar locations. Exception: Conductors run above the top level of a window shall be permitted to be less than the 900 mm (3 ft) requirement. (2) Vertical Clearance. The vertical clearance of final spans above or within 900 mm (3 ft) measured horizontally of platforms, projections, or surfaces that will permit personal contact shall be maintained in accordance with 225.18. (3) Building Openings. The overhead branch-circuit and feeder conductors shall not be installed beneath openings through which materials may be moved, such as openings in farm and commercial buildings, and shall not be installed where they obstruct entrance to these openings. (E) Zone for Fire Ladders. Where buildings exceed three stories or 15 m (50 ft) in height, overhead lines shall be arranged, where practicable, so that a clear space (or zone) at least 1.8 m (6 ft) wide will be left either adjacent to the buildings or beginning not over 2.5 m (8 ft) from them to facilitate the raising of ladders when necessary for fire fighting. 225.20 Protection Against Physical Damage. Conductors instal?led on buildings, structures, or poles shall be protected against physical damage as provided for services in 230.50. 225.21 Multiconductor Cables on Exterior Surfaces of Buildings (or Other Structures). Supports for multiconductor cables on exterior surfaces of buildings (or other structures) shall be as provided in 230.51. 225.22 Raceways on Exterior Surfaces of Buildings or Other Structures. Raceways on exteriors of buildings or other structures shall be arranged to drain and shall be listed or approved for use in wet locations. ENHANCED CONTENT Collapse If raceways are exposed to weather or temperature changes, condensation is likely to occur, causing moisture to accumulate within raceways at low points of the installation and in junction boxes. Therefore, raceways are required to be installed so as to allow moisture to drain from the raceway through drain holes or other means provided at appropriate locations. 225.24 Outdoor Lampholders. Where outdoor lampholders are attached as pendants, the connections to the circuit wires shall be staggered. Where such lampholders have terminals of a type that puncture the insulation and make contact with the conductors, they shall be attached only to conductors of the stranded type. 225.25 Location of Outdoor Lamps. Locations of lamps for outdoor lighting shall be below all energized conductors, transformers, or other electric utilization equipment, unless either of the following apply: * (1) Clearances or other safeguards are provided for relamping operations. * (2) Equipment is controlled by a disconnecting means that is lockable open in accordance with 110.25. ENHANCED CONTENT Collapse The objective is to protect personnel during relamping of outdoor luminaires. Section 225.18 requires a minimum clearance of 10 feet above grade or platforms for open conductors. In some cases, it may be difficult to keep all electrical equipment above the lamps. Section 225.25(1) allows other clearances or safeguards to permit safe relamping, while the reference to 110.25 provides another alternative for safe relamping through the use of a disconnecting means that can be locked in the open or off position. 225.26 Vegetation as Support. Vegetation such as trees shall not be used for support of overhead conductor spans. ENHANCED CONTENT Collapse Overhead conductor spans attached to a tree are subject to damage over the course of time because normal tree growth around the attachment device causes the mounting insulators to break. Normal growth can also cause tree bark to grow around the insulation. This requirement reduces the likelihood of chafing or degradation of the conductor insulation, which can create a shock hazard for tree trimmers and tree climbers. Outdoor luminaires and associated equipment are permitted by 410.36(G) to be supported by trees. To prevent the chafing damage, conductors are run up the tree from an underground wiring method. See also 300.5(D)(1) for requirements on the protection of direct-buried conductors emerging from below grade. 225.27 Raceway Seal. Where a raceway enters a building or structure from outside, it shall be sealed in accordance with 300.5(G) and 300.7(A). Spare or unused raceways shall also be sealed. Sealants shall be identified for use with cable insulation, conductor insulation, bare conductor, shield, or other components. Part II. Buildings or Other Structures Supplied by a Feeder(s) or Branch Circuit(s) 225.30 Number of Supplies. A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (F). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit. Where a branch circuit or feeder originates in these additional buildings or other structures, only one feeder or branch circuit shall be permitted to supply power back to the original building or structure, unless permitted in 225.30(A) through (F). ENHANCED CONTENT Collapse Part II covers outside branch circuits and feeders as the source of electrical supply for buildings and structures. Understanding the definitions of service point, service, service equipment, feeder, and branch circuit is important. Determining what constitutes a set of feeder or branch-circuit conductors versus a set of service conductors requires a clear understanding of where the service point is located and where the service and service equipment for a premises are located. In some cases, particularly with medium- and high-voltage distribution, the service location of a campus or multibuilding facility is a switchyard or substation. With the location of the service point and service equipment established, the requirements for outside branch circuits and feeders from Part II (and Article 235 if over 1000 volts) can be properly applied. The feeders and branch circuits covered in Part II might originate in one building or structure and supply another building or structure, or they might originate in outdoor equipment such as free-standing switchboards, switchgear, transformers, or generators and supply equipment located in buildings or structures. See also Article 230, which contains similar requirements for services. (A) Special Conditions. Additional feeders or branch circuits shall be permitted to supply the following: * (1) Fire pumps * (2) Emergency systems * (3) Legally required standby systems * (4) Optional standby systems * (5) Parallel power production systems * (6) Systems designed for connection to multiple sources of supply for the purpose of enhanced reliability * (7) Electric vehicle power transfer systems listed, labeled, and identified for more than a single branch circuit or feeder * (8) Docking facilities and piers (B) Common Supply Equipment. Where feeder conductors originate in the same panelboard, switchboard, or other distribution equipment, and each feeder terminates in a single disconnecting means, not more than six feeders shall be permitted. Where more than one feeder is installed in accordance with this section, all feeder disconnects supplying the building or structure shall be grouped in the same location, and the requirements of 225.33 shall not apply. Each disconnect shall be marked to indicate the load served. (C) Special Occupancies. By special permission, additional feeders or branch circuits shall be permitted for either of the following: * (1) Multiple-occupancy buildings where there is no space available for supply equipment accessible to all occupants * (2) A single building or other structure sufficiently large to make two or more supplies necessary (D) Capacity Requirements. Additional feeders or branch circuits shall be permitted where the capacity requirements are in excess of 2000 amperes at a supply voltage of 1000 volts or less. (E) Different Characteristics. Additional feeders or branch circuits shall be permitted for different voltages, frequencies, or phases, or for different uses such as control of outside lighting from multiple locations. (F) Documented Switching Procedures. Additional feeders or branch circuits shall be permitted to supply installations under single management where documented safe switching procedures are established and maintained. ENHANCED CONTENT Collapse Buildings on college campuses, multibuilding industrial facilities, and multibuilding commercial facilities are permitted to be supplied by secondary loop supply (secondary selective) networks if documented switching procedures are in place. The switching procedures must establish a method to safely operate switches for the facility during maintenance and during alternative supply and emergency supply conditions. Keyed interlock systems are often used to reduce the likelihood of inappropriate switching procedures that could result in hazardous conditions. 225.31 Disconnecting Means. (A) General. Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure. (B) Location. The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall apply. Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained, and where the installation is monitored by qualified individuals, the disconnecting means shall be permitted to be located elsewhere on the premises. Exception No. 2: For buildings or other structures qualifying under 685.1, the disconnecting means shall be permitted to be located elsewhere on the premises. Exception No. 3: For towers or poles used as lighting standards, the disconnecting means shall be permitted to be located elsewhere on the premises. Exception No. 4: For poles or similar structures used only for support of signs installed in accordance with 600.1, the disconnecting means shall be permitted to be located elsewhere on the premises. ENHANCED CONTENT Collapse Although the requirement for locating the disconnecting means for a feeder or branch circuit supplying a structure is essentially the same as that specified for services in 230.70(A), there is an important difference. Where a building or structure is supplied by a feeder or branch circuit, the disconnecting means must always be nearest the point of entrance of the conductors whether inside or outside the building or structure supplied, unless one of the exceptions can be applied. Many campus-style facilities are supplied by a single utility service, in which the service disconnecting means is remote from the buildings or structures supplied. The supply conductors to the campus buildings are feeders or branch circuits, and this requirement applies to conductors that supply a building as well as conductors that pass through a building. The exhibit below shows an example of a disconnecting means for a generator feeder that can be used to meet the requirements of Article 225, Article 445, and Articles 700, 701, or 702 as applicable. The disconnecting means is required to be “within sight” of the building or structure supplied by the generator. An exception to 700.12(D)(4) permits the disconnecting means for an outdoor generator supplying an emergency system to be located other than within sight of the building(s) or structure(s) supplied by the generator. That exception contains the same conditions as used in 225.31(B), Exception No. 1. 225.33 Maximum Number of Disconnects. (A) General. The disconnecting means for each supply permitted by 225.30 shall consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or switchgear. There shall be no more than six disconnects per supply grouped in any one location. Exception: For the purposes of this section, disconnecting means used solely for the control circuit of the ground-fault protection system, or the control circuit of the power-operated supply disconnecting means, instal?led as part of the listed equipment, shall not be considered a supply disconnecting means. (B) Single-Pole Units. Two or three single-pole switches or breakers capable of individual operation shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all ungrounded conductors with no more than six operations of the hand. 225.34 Grouping of Disconnects. (A) General. The two to six disconnects as permitted in 225.33 shall be grouped. Each disconnect shall be marked to indicate the load served. Exception: One of the two to six disconnecting means permitted in 225.33, where used only for a water pump also intended to provide fire protection, shall be permitted to be located remote from the other disconnecting means. (B) Additional Disconnecting Means. The one or more additional disconnecting means for fire pumps or for emergency, legally required standby or optional standby system permitted by 225.30 shall be installed sufficiently remote from the one to six disconnecting means for normal supply to minimize the possibility of simultaneous interruption of supply. 225.35 Access to Occupants. In a multiple-occupancy building, each occupant shall have access to the occupant’s supply disconnecting means. Exception: In a multiple-occupancy building where electric supply and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the supply disconnecting means supplying more than one occupancy shall be permitted to be accessible to authorized management personnel only. 225.36 Type of Disconnecting Means. The disconnecting means specified in 225.31 shall be a circuit breaker, molded case switch, general-use switch, snap switch, or other approved means. Where applied in accordance with 250.32(B)(1), Exception No. 1, the disconnecting means shall be suitable for use as service equipment. ENHANCED CONTENT Collapse The feeder or branch-circuit disconnecting means is required to be suitable for use as service equipment only where the feeder grounded conductor is also used as the return path for ground-fault current per 250.32(B)(1), Exception No. 1. A three- or fourway snap switch cannot be used as a disconnecting means for an outside branch circuit or feeder because it does not provide a positive indication that the circuit is disconnected. 225.37 Identification. Where a building or structure has any combination of feeders, branch circuits, or services passing through it or supplying it, a permanent plaque or directory shall be installed at each feeder and branch-circuit disconnect location denoting all other services, feeders, or branch circuits supplying that building or structure or passing through that building or structure and the area served by each. Exception No. 1: A plaque or directory shall not be required for large-capacity multibuilding industrial installations under single management, where it is ensured that disconnection can be accomplished by establishing and maintaining safe switching procedures. Exception No. 2: This identification shall not be required for branch circuits installed from a dwelling unit to a second building or struc