Outside Branch Circuits & Feeders ARTICLE 225

Isolating Switches Over 600 volts

225.51 Where oil switches or air, oil, vacuum, or sulfur hexafluoride circuit breakers constitute a building disconnecting means, an isolating switch with vis- ible break contacts and meeting the requirements of 230.204(B), (C), and (D) shall be installed on the supply side of the disconnecting means and all associated equipment. Exception: The isolating switch shall not be required where the disconnecting means is mounted on removable truck panels or metal-enclosed switchgear units that cannot be opened unless the circuit is disconnected and that, when removed from the normal operating position, automatically disconnect the circuit breaker or switch from all energized parts.

600 Volts Between Conductors

Circuits exceeding 277 volts, nominal, to ground and not exceeding 600 volts, nominal, between conductors shall be permitted to supply the auxiliary equipment of electric-discharge lamps in ac- cordance with 210.6(D)(1

277 Volts to Ground

Circuits exceeding 120 volts, nominal, between conductors and not exceeding 277 volts, nominal, to ground shall be permitted to supply luminaires for illumination of outdoor areas of industrial establish- ments, office buildings, schools, stores, and other commer- cial or public buildings where the luminaires are not less than 900 mm (3 ft) from windows, platforms, fire escapes, and the like.

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 con- ductors: a. 300 volts or less — 600 mm (24 in.) b. Over 300 volts — 750 mm (30 in.) (3) Communications conductors below power conductors — same as power conductors (4) Communications conductors alone — no requirement

Disconnect Type over 600 volts

Each building or structure disconnect shall simultaneously disconnect all ungrounded supply conduc- tors it controls and shall have a fault-closing rating not less than the maximum available short-circuit current available at its supply terminals. Where fused switches or separately mounted fuses are in- stalled, the fuse characteristics shall be permitted to contribute to the fault closing rating of the disconnecting means.

Disconnect Construction.

Exception: For garages and outbuildings on residential property, snap switches or sets of 3-way or 4-way snap switches shall be permitted as the disconnecting means.

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 win- dow shall be permitted to be less than the 900-mm (3-ft) requirement

One-Family Dwelling.

For a one-family dwelling, the feeder disconnecting means shall have a rating of not less than 100 amperes, 3-wire. (D) All Others. For all other installations, the feeder or branch-circuit disconnecting means shall have a rating of not less than 60 amperes

Two-Circuit Installations

For installations consisting of not more than two 2-wire branch circuits, the feeder or branch-circuit disconnecting means shall have a rating of not less than 30 amperes.

One-Circuit Installation

For installations to supply only limited loads of a single branch circuit, the branch circuit disconnecting means shall have a rating of not less than 15 amperes

Clearance 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).

Open-Conductor Supports

Open conductors shall be supported on glass or porcelain knobs, racks, brackets, or strain insulators.

Overhead Spans

Open individual conductors shall not be smaller than the following: (1) For 600 volts, nominal, or less, 10 AWG copper or 8 AWG aluminum for spans up to 15 m (50 ft) in length, and 8 AWG copper or 6 AWG aluminum for a longer span unless supported by a messenger wire (2) For over 600 volts, nominal, 6 AWG copper or 4 AWG aluminum where open individual conductors, and 8 AWG copper or 6 AWG aluminum where in cable

Festoon Lighting

Overhead conductors for festoon lighting shall not be smaller than 12 AWG unless the con- ductors are supported by messenger wires. In all spans ex- ceeding 12 m (40 ft), the conductors shall be supported by messenger wire. The messenger wire shall be supported by strain insulators. Conductors or messenger wires shall not be attached to any fire escape, downspout, or plumbing equipment.

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 raintight in wet locations.

Clearances over Buildings and Other Structures

Table 225.61 22 kV Nominal to Ground or Less. Over 22 kV Nominal to Ground. Clearances for the categories shown in Table 225.61 shall be increased by 10 mm (0.4 in.) per kV above 22,000 volts.

Wiring on Buildings

The installation of outside wiring on surfaces of buildings shall be permitted for cir- cuits of not over 600 volts, nominal, as open wiring on nsulators, as multiconductor cable, as Type MC cable, as Type UF cable, as Type MI cable, as messenger-supported wiring, in rigid metal conduit, in intermediate metal con- duit, in rigid nonmetallic conduit, in cable trays, as cable- bus, in wireways, in auxiliary gutters, in electrical metallic tubing, in flexible metal conduit, in liquidtight flexible metal conduit, in liquidtight flexible nonmetallic conduit, and in busways. Circuits of over 600 volts, nominal, shall be installed as provided in 300.37

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 buildings' openings.

Vertical Clearance.

The vertical clearance of final spans above, or within 900 mm (3 ft) measured horizontally of, platforms, projections, or surfaces from which they might be reached shall be maintained in accordance with 225.18.

Access to Overcurrent Protective Devices

Where a feeder overcurrent device is not readily accessible, branch-circuit overcurrent devices shall be installed on the load side, shall be mounted in a readily accessible location, and shall be of a lower ampere rating than the feeder over- current device.

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

Outdoor Lampholders

Where outdoor lamphold- ers 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.

Conductor Covering

Where within 3.0 m (10 ft) of any building or structure other than supporting poles or towers, open individual (aerial) overhead conductors shall be insulated or covered. Conductors in cables or raceways, except Type MI cable, shall be of the rubber-covered type or thermoplastic type and, in wet locations, shall comply with 310.8. Conductors for festoon lighting shall be of the rubber-covered or thermoplastic type. Exception: Equipment grounding conductors and grounded circuit conductors shall be permitted to be bare or covered as specifically permitted elsewhere in this Code

Horizontal Clearances

shall not be less than 900 mm (3 ft)

Clearance for Overhead Conductors and Cables.not over 600 volts

(1) 3.0 m (10 ft) — above finished grade, sidewalks, or from any platform or projection from which they might be reached 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 drive- ways, 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, park- ing areas subject to truck traffic, driveways on other than residential property, and other land traversed by vehicles, such as cultivated, grazing, forest, and orchard

Clearances from Buildings for Conductors of Not over 600 Volts

A) Above Roofs. Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 2.5 m (8 ft) 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 traffıc shall have a vertical clear- ance from the roof surface in accordance with the clear- ance 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 ver- tical 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.

Clearances over Roadways, Walkways, Rail, Water, and Open Land. (A) 22 kV, Nominal, to Ground or Less

Table 225.60 ) Over 22 kV Nominal to Ground. Clearances for the categories shown in Table 225.60 shall be increased by 10 mm (0.4 in.) per kV above 22,000 volts. Special Cases. For special cases, such as where cross- ings will be made over lakes, rivers, or areas using large vehicles such as mining operations, specific designs shall be engineered considering the special circumstances and shall be approved by the authority having jurisdiction.

Open conductors shall be separated from open conductors of other circuits or systems by not less than __ in.?

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Disconnecting Means Location

225.32 Location. The disconnecting means shall be in- stalled 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 con- ductors. For the purposes of this section, the requirements in 230.6 shall be utilized.

More Than One Building or Other Structure - Number of Supplies

Number of Supplies. Where more than one build- ing or other structure is on the same property and under single management, each additional building or other struc- ture that is served by a branch circuit or feeder on the load side of the service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit. (A) Special Conditions. Additional feeders or branch cir- cuits 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 Special Occupancies. By special permission, addi- tional feeders or branch circuits shall be permitted 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 600 volts or less. 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. Documented Switching Procedures. Additional feed- ers or branch circuits shall be permitted to supply installa- tions under single management where documented safe switching procedures are established and maintained for disconnection

Grouping of Disconnects

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 per- mitted 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. Additional Disconnecting Means. The one or more additional disconnecting means for fire pumps or for emer- gency, 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.