PEC 2017 – Article 2.25

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Article 2.25 – OUTSIDE BRANCH CIRCUITS AND FEEDERS

2.25.1 General

2.25.1.1 Scope.

This article covers requirements for outside branch circuits and feeders run on or between buildings, structures, or poles on the premises; and electrical equipment and wiring for the supply of utilization equipment that is located on or attached to the outside of buildings, structures, or poles.

FPN: For additional information on wiring over 1 000 volts, see ANSI/IEEE C2-2012, National Electrical Safety Code.

 2.25.1.3 Other Articles.

Application of other articles, including additional requirements to specific cases of equipment and conductors, is shown in Table 2.25.1.3.

2.25.1.4 Conductor Covering.

Where within 3 000 mm of any building or structure other than supporting poles or towers, open individual (aerial) overhead conductors shall be insulated for the nominal voltage. The insulation of conductors in cables or raceways, except Type MI cable, shall be of thermoset or thermoplastic type and, in wet locations, shall comply with 3.10.2.1(C). The insulation of 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.

2.25.1.5 Size of Conductors 600 Volts, Nominal, or Less.

The ampacity of outdoor branch-circuit and feeder conductors shall be in accordance with 3.10.2.6 based on loads as determined under 2.20.2.1 and Part 2.20.3.

2.25.1.6 Conductor Size and Support.

(A) Overhead Spans. Open individual conductors shall not be smaller than the following:

(1) For 1 000 volts, nominal, or less, 5.5 mm² (2.6 mm dia.) copper or 8.0 mm² (3.2 mm dia.) aluminum for spans up to 15 m in length, and 8.0 mm² (3.2 mm dia.) copper or 14 mm² aluminum for a longer span unless supported by a messenger wire

(2) For over 1000 volts, nominal, 14 mm² copper or 22 mm² aluminum where open individual conductors, and 8.0 mm² (3.2 mm dia.) copper or 14 mm² aluminum where in cable

(B) Festoon Lighting. Overhead conductors for festoon lighting shall not be smaller than 3.5 mm² (2.0 mm dia.) unless the conductors are supported by messenger wires. In all spans exceeding 12 m, 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.

2.25.1.7 Lighting Equipment Installed Outdoors.

(A) General. For the supply of lighting equipment installed outdoors, the branch circuits shall comply with Article 2.10 and 2.25.1.7(B) through (D).

(B) Common Neutral. The ampacity of the neutral conductor shall not be less than the maximum net calculated load current between the neutral conductor and all ungrounded conductors connected to any one phase of the circuit.

(C) 265 Volts to Ground. Circuits exceeding 115 volts. nominal, between conductors and not exceeding 265 volts, nominal, to ground shall be permitted to supply luminaires for illumination of outdoor areas of industrial establishments, office buildings, schools, stores, and other commercial or public buildings.

(D) 1000 Volts Between Conductors. Circuits exceeding 265 volts, nominal, to ground and not exceeding 1000 volts, nominal, between conductors shall be permitted to supply the auxiliary equipment of electric-discharge lamps in accordance with 2.10.1.6(D) (1).

2.25.1.8 Calculation of Loads 1000 Volts, Nominal, or Less.

(A) Branch Circuits. The load on outdoor branch circuits shall be as determined by 2.20.2.1.

(B) Feeders. The load on outdoor feeders shall be as determined by Part 2.20.3.

2.25.1.10 Wiring on Buildings (or Other Structures).

The installation of outside wiring on surfaces of buildings (or other structures) shall be permitted for circuits not over 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) Multiconductor cable
  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 UF cable
  18. Wireways

2.25.1.11 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 in installed in accordance with the requirements of 2.30.4.13. Overhead branch circuits and feeders attached to buildings or structures shall be installed in accordance with the requirements of 2.30.4.15.

2.25.1.12 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.

2.25.1.14 Open-Conductor Spacings.

(A) 1000 Volts, Nominal, or Less. Conductors of 1000 volts, nominal, or less, shall comply with the spacings provided in Table 2.30.4.12 (C).

(B) Over 1000 Volts, Nominal. Conductors of over 1000 volts, nominal, shall comply with the spacings provided in 1.10.3.7 and 4.90.2.4.

(C) Separation from Other Circuits. Open conductors shall be separated from open conductors of other circuits or systems by not less than 100 mm.

(D) Conductors on Poles. Conductors on poles shall have a separation of not less than 300 mm 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 communication conductors – 750 mm

(2) Power conductors alone or above communications conductors:

a. 300 volts or less – 600 mm

b. Over 300 volts – 750 mm

(3) Communications conductors below conductors – same as power conductors

(4) Communications conductors alone – no requirement

2.25.1.15 Supports over Buildings.

 Supports over a building shall be in accordance with 2.30.2.8.

2.25.1.16 Attachment to Buildings.

(A) Point of Attachment. The point of attachment to a building shall be in accordance with 2.30.2.5.

(B) Means of Attachment. The means of attachment to a building shall be in accordance with 2.30.2.6.

2.25.1.17 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 2.25.1.17(A) and (B).

(A) Strength. The mast shall have adequate strength or be supported by braces or guys 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.

2.25.1.18 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) 3000 mm – 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) 3700 mm – 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) 4500 mm- for those areas listed in the 3 700 mm classification where the voltage exceeds 300 volts to ground

(4) 5500 mm- 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) 7500 mm – over track rails of railroads

2.25.1.19 Clearances from Buildings for Conductors of Not over 1000 Volts, Nominal.

(A) Above Roofs. Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 2700 mm above the roof surface. The vertical clearance above the roof level shall be maintained for a distance not less than 900 mm 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 2.25.1.18.

Exception No. 2: Where the voltage between conductors does not exceed 300, and the roof has a slope of 100 mm in 300 mm or greater, a reduction in clearance to 900 mm 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 shall be permitted if (1) not more than 1800 mm of the conductors, 1200 mm 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 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.

(C) Horizontal Clearances. Clearances shall not be less than 900 mm.

(D) Final Spans. Final spans of feeders or branch circuits shall comply with 2.25.1.19(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 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 requirement.

(2) Vertical Clearance. The vertical clearance of final spans above or within 900 mm measured horizontally of platforms, projections. or surfaces that will permit personal contact shall be maintained in accordance with 2.25.1.18.

(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 in height, overhead lines shall be arranged, where practicable, so that a clear space (or zone) at least 1800 m wide will be left either adjacent to the buildings or beginning not over 2500 mm from them to facilitate the raising of ladders when necessary for fire fighting.

2.25.1.20 Protection Against Physical Damage.

Conductors installed on buildings, structures, or poles shall be protected against physical damage as provided for services in 2.30.4.11.

2.25.1.21 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 2.30.4.12.

2.25.1.22 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 suitable for use in wet locations.

2.25.1.24 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.

2.25.1.25 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 in accordance with 1.10.1.25.

2.25.1.26 Vegetation as Support.

Vegetation such as trees shall not be used for support of overhead conductor spans.

2.25.1.27 Raceway Seal.

Where a raceway enters a building or structure from outside, it shall be sealed. 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.

2.25.2 Buildings or Other Structures Supplied by a Feeder(s) or Branch Circuit(s)

2.25.2.1 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 2.25.2.1(A) through (E). 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 2.25.2.1(A) through (E).

(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 charging systems listed, labeled, and identified for more than a single branch circuit or feeder

(B) Special Occupancies. Additional feeders or branch circuits shall be permitted for either of the following:

(1) Multiple-occupancy buildings or site developments with group of single detached 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

(C) 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.

(D) 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.

(E) 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 for disconnection.

2.25.2.2 Disconnecting Means.

Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.

2.25.2.3 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 2.30.1.6 shall be utilized.

Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained for disconnection, 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 the provisions of Article 6.85. 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 Article 6.0, the disconnecting means shall be permitted to be located elsewhere on the premises.

2.25.2.4 Maximum Number of Disconnects.

(A) General. The disconnecting means for each supply permitted by 2.25.2.1 shall consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a group of separate enclosures adjacent to each other, 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, installed 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.

2.25.2.5 Grouping of Disconnects.

(A) General. The two to six disconnects as permitted in 2.25.2.4 shall be grouped adjacent to each other. Each disconnect shall be marked to indicate the load served.

Exception: One of the two to six disconnecting means permitted in 2.25.2.4, 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 2.25.2.1 shall be installed sufficiently remote from the one to six disconnecting means for normal supply to minimize the possibility of simultaneous interruption of supply.

2.25.2.6 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.

2.25.2.7 Type of Disconnecting Means.

 The disconnecting means specified in 2.25.2.2 shall be comprised of a circuit breaker, molded case switch, general-use switch, snap switch, or other approved means. Where applied in accordance with 2.50.2.13(B). Exception No. 1, the disconnecting means shall be suitable for use as service equipment.

2.25.2.8 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 structure.

2.25.2.9 Disconnect Construction.

Disconnecting means shall meet the requirements of 2.25.2.9(A) through (D).

(A) Manually or Power Operable. The disconnecting means shall consist of either (1) a manually operable switch or a circuit breaker equipped with a handle or other suitable operating means or (2) a power-operable switch or circuit breaker, provided the switch or circuit breaker can be opened by hand in the event of a power failure.

(B) Simultaneous Opening of Poles. Each building or structure disconnecting means shall simultaneously disconnect all ungrounded supply conductors that it controls from the building or structure wiring system.

(C) Disconnection of Grounded Conductor. Where the building or structure disconnecting means does not disconnect the grounded conductor from the grounded conductors in the building or structure wiring, other means shall be provided for this purpose at the location of the disconnecting means. A terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permitted for this purpose.

In a multisection switchboard or switchgear, disconnects for the grounded conductor shall be permitted to be in any section of the switchboard or switchgear, if the switchboard section or switchgear section is marked to indicate a grounded conductor disconnect is contained within the equipment.

(D) Indicating. The building or structure disconnecting means shall plainly indicate whether it is in the open or closed position.

2.25.2.10 Rating of Disconnect.

The feeder or branch circuit disconnecting means shall have a rating of not less than the calculated load to be supplied, determined in accordance with Parts 2.20.1 and 2.20.2 for branch circuits, Part 2.20.3 and 2.20.4 for feeders, or Part 2.20.5 for farm loads. Where the branch circuit or feeder disconnecting means consists of more than one switch or circuit breaker, as permitted by 2.25.2.4. combining the ratings of all the switches or circuit breakers for determining the rating of the disconnecting means shall be permitted. In no case shall the rating be lower than specified in 2.25.2.10(A). (B), (C), or (E).

(A) 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.

(B) One-Circuit Installation – Dwelling Unit. For a dwelling unit with a single branch circuit as permitted in Section 2.10.1.11(C)(5), the branch circuit disconnect means shall have a rating of not less than 20 amperes.

(C) 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.

(D) One-Family Dwelling. For a one-family dwelling, the feeder disconnecting means shall have a rating of not less than 60 amperes, 3-wire.

(E) All Others. For all other installations, the feeder or branch-circuit disconnecting means shall have a rating of not less than 60 amperes.

2.25.2.11 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.

2.25.3 Over 1000 Volts

2.25.3.1 Sizing of Conductors.

The sizing of conductors over 1000 volts shall be in accordance with 2.10.2.2(B) for branch circuits and 2.15.1.2(B) for feeders.

2.25.3.2 Isolating Switches.

 Where oil switches or air, oil, vacuum, or sulfur hexafluoride circuit breakers constitute a building disconnecting means, an isolating switch with visible 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 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.

2.25.3.3 Disconnecting Means.

(A) Location. A building or structure disconnecting means shall be located in accordance with 2.25.3.3. or, if not readily accessible, it shall be operable by mechanical linkage from a readily accessible point.

For multibuilding industrial installations under single management, it shall be electrically operated by a readily accessible, remote-control device in a separate building or structure.

(B) Type. Each building or structure disconnect shall simultaneously disconnect all ungrounded supply conductors it controls and shall have a fault-closing rating not less than the maximum available short-circuit current available at its supply terminals.

Exception: Where the individual disconnecting means consists of fused cutouts, the simultaneous disconnection of all ungrounded supply conductors shall not be required if there is a means to disconnect the load before opening the cutouts. A permanent legible sign shall be installed adjacent to the fused cutouts and shall read DISCONNECT LOAD BEFORE OPENING CUTOUTS.

Where fused switches or separately mounted fuses are installed, the fuse characteristics shall be permitted to contribute to the fault closing rating of the disconnecting means.

(C) Locking. Disconnecting means shall be lockable in accordance with 1.10.1.25.

Exception: Where an individual disconnecting means consist of fused cutouts, a suitable enclosure capable of being locked and sized to contain all cutout fuse holders at a convenient location to the fused cutouts.

(D) Indicating. Disconnecting means shall clearly indicate whether they are in the open “off” or closed “on” position.

(E) Uniform Position. Where disconnecting means handles are operated vertically, the “up” position of the handle shall be the “on” position.

Exception: A switching device having more than one “on” position, such as a double-throw switch, shall not be required to comply with this requirement.

(F) Identification. Where a building or structure has any combination of feeders, branch circuits, or services passing through or supplying it, a permanent plaque or directory shall be installed at each feeder and branch-circuit disconnect location that denotes 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.

2.25.3.7 Inspections and Tests.

(A) Pre-Energization and Operating Tests. The complete electrical system design, including settings for protective, switching, and control circuits, shall be prepared in advance and made available on request to the Office of the Building Official/EE and shall be performance tested when first installed on-site. Each protective, switching, and control circuit shall be adjusted in accordance with the system design and tested by actual operation using current injection or equivalent methods as necessary to ensure that each and every such circuit operates correctly.

(1) Instrument Transformers. All instrument transformers shall be tested to verify correct polarity and burden.

(2) Protective Relays. Each protective relay shall be demonstrated to operate by injecting current or voltage, or both, at the associated instrument transformer output terminal and observing that the associated switching and signaling functions occur correctly and in proper time and sequence to accomplish the protective function intended.

(3) Switching Circuits. Each switching circuit shall be observed to operate the associated equipment being switched.

(4) Control and Signal Circuits. Each control or signal circuit shall be observed to perform its proper control function or produce a correct signal output.

(5) Metering Circuits. All metering circuits shall be verified to operate correctly from voltage and current sources in a similar manner to protective relay circuits.

(6) Acceptance Tests. Complete acceptance tests shall be performed, after the substation installation is completed, on all assemblies, equipment, conductors, and control and protective systems, as applicable, to verify the integrity of all the systems.

(7) Relays and Metering Utilizing Phase Differences. All relays and metering that use phase differences for operation shall be verified by measuring phase angles at the relay under actual load conditions after operation commences.

(B) Test Report. A test report covering the results of the tests required in 2.25.3.7(A) shall be delivered to the Office of the Building Official/EE prior to energization.

FPN: For an example of acceptance specifications, see ANSI/NETA ATS-2013, Acceptance Testing Specifications for Electrical Power Distribution Equipment and Systems, published by the InterNational Electrical Testing Association.

2.25.3.11 Clearances over Roadways, Walkways, Rail, Water, and Open Land.

(A) 22 kV. Nominal, to Ground or Less. The clearances over roadways. walkways, rail, water, and open land for conductors and live parts up to 22 kV. nominal, to ground or less shall be not less than the values shown in Table 2.25,3.11

(B) Over 22 kV Nominal to Ground. Clearances for the categories shown in Table 2.25.3.11 shall be increased by 10 mm per kV above 22 000 volts.

(C) Special Cases. For special cases, such as where crossings will be made over lakes, rivers, or areas using large vehicles such as mining operations, specific designs shall be engineered considering the special circumstances.

FPN: For additional information, see ANSI/IEEE C2-2012, National Electrical Safety Code.

LocationClearance (m)
Open land subject to vehicles, cultivation, or grazing5.6
Roadways, driveways, parking lots, and alleys5.6
Walkways4.1
Rails8.1
Spaces and ways for pedestrians and restricted traffic4.4
Water areas not suitable for boating5.2
Table 2.25.3.11 Clearances over Roadways, Walkways, Rail, Water, and Open Land

2.25.3.12 Clearances over Buildings and Other Structures.

(A) 22 kV Nominal to Ground or Less. The clearances over buildings and other structures for conductors and live parts up to 22 kV, nominal, to ground or less shall be not less than the values shown in Table 2.25.3.12.

(B) Over 22 kV Nominal to Ground. Clearances for the categories shown in Table 2.25.3.12 shall be increased by 10 mm per kV above 22,000 volts.

FPN: For additional information, see ANSI/IEEE C2-2012, National Electrical Safety Code.

Clearance from Conductors or Live Parts fromHorizontal (m)Vertical (m)
Building walls, projections, and windows2.3
Balconies, catwalks, and similar areas accessible to people2.34.1
Over or under roofs or projections not readily accessible to people3.8
Over roofs accessible to vehicles but not trucks4.1
Over roofs accessible to trucks5.6
Other structures2.3
Table 2.25.3.12 Clearances over Buildings and Other Structures