SERVICES

230-1. Scope. This article covers service conductors and equipment for control and protection of services and their installation requirements. (FPN): See Diagram 230-1. A. General. 230-2. Number of Services. A building or other structure served shall be supplied by only one service. Where more than one service is permitted by any of the following exceptions, a permanent plaque or directory shall be installed at each service drop or lateral or at each service-equipment location denoting all other services on or in that building or structure and the area served by each. Exception No. 1: For fire pumps where a separate service is required. Exception No. 2: For emergency, legally required standby, optional standby, or parallel power production systems where a separate service is required. ARTICLE 230 - SERVICES 70-71 General Part A Overhead Service Drop Conductors Part B Underground Service-Lateral Conductors Part C Service-Entrance Conductors Part D Service Equipment - General Part E Service Equipment - Disconnecting Means Part F Service Equipment - Overcurrent Protection Part G Services over 600 Volts, Nominal Part H SOURCE Overhead Underground Last pole Street main Part B Service drop Service lateral Part C 230-24 Clearances Depth of burial 230-49 and protection Service head Terminal box, meter, or other enclosure Service-entrance Part D conductors Service equipment General Part E grounding 230-63 Disconnecting means Part F Overcurrent protection Part G Branch circuits Articles 210, 225 Feeders Articles 215, 225 Diagram 230-1. Services. 70-72 NATIONAL ELECTRICAL CODE Exception No. 3: Multiple-Occupancy Buildings. By special permission, in multiple-occupancy buildings where there is no available space for service equipment accessible to all the occupants. Exception No. 4: Capacity Requirements. Two or more services shall be permitted: a. Where the capacity requirements are in excess of 2000 amperes at a supply voltage of 600 volts or less; or b. Where the load requirements of a single-phase installation are greater than the serving agency normally supplies through one service; or C. By special permission. Exception No. 5: Buildings of Large Area. By special permission, for a single building or other structure sufficiently large to make two or more services necessary. Exception No. 6: For different characteristics, such as for different voltages, frequencies, or phases, or for different uses, such as for different rate schedules. Exception No. 7: For the purpose of Section 230-40, Exception No. 2 only, underground sets of conductors, size ¹/₀ and larger, running to the same location and connected together at their supply end but not connected together at their load end shall be considered to be one service lateral. 230-3. One Building or Other Structure Not to Be Supplied Through Another. Service conductors supplying a building or other structure shall not pass through the interior of another building or other structure. (FPN): See Section 230-6 for concrete or masonry-encased conductors considered outside of a building. 230-6. Conductors Considered Outside of Building. Conductors shall be considered outside of a building or other structure under any of the following conditions: (1) where installed under not less than 2 inches (50.8 mm) of concrete beneath a building or other structure; (2) where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 2 inches (50.8 mm) thick; or (3) where installed in a transformer vault conforming to the requirements of Article 450, Part C. 230-7. Other Conductors in Raceway or Cable. Conductors other than service conductors shall not be installed in the same service raceway or service cable. Exception No. 1: Grounding conductors. Exception No. 2: Load management control conductors having overcurrent protection. 230-8. Raceway Seal. Where a service raceway enters from an underground distribution system, it shall be sealed in accordance with Section 300-5. Spare or unused raceways shall also be sealed. Sealants shall be identified for use with the cable insulation, shield, or other components. ARTICLE 230 - SERVICES 70-73 230-9. Clearance from Building Openings. Service conductors installed as open conductors or multiconductor cable without an overall outer jacket shall have a clearance of not less than 3 feet (914 mm) from windows that are designed to be opened, doors, porches, fire escapes, or similar locations. Exception: Conductors run above the top level of a window shall be permitted to be less than the 3 feet (914 mm) requirement above. Overhead service 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 will obstruct entrance to these building openings. 230-10. Service Conductors. The conductors from the service point to the service disconnecting means shall be considered service conductors. B. Overhead Service-Drop Conductors 230-21. Overhead Supply. Overhead conductors to a building or other structure (such as a pole) on which a meter or disconnecting means is installed shall be considered as a service drop and installed accordingly. (FPN): Example: Farm loads in Part D of Article 220. 230-22. Insulation or Covering. Service conductors shall normally withstand exposure to atmospheric and other conditions of use without detrimental leakage of current. Individual conductors shall be insulated or covered with an extruded thermoplastic or thermosetting insulating material. Exception: The grounded conductor of a multiconductor cable shall be permitted to be bare. 230-23. Size and Rating. (a) General. Conductors shall have sufficient ampacity to carry the load without a temperature rise detrimental to the covering or insulation of the conductors and shall have adequate mechanical strength. (b) Minimum Size. The conductors shall not be smaller than No. 8 copper or No. 6 aluminum or copper-clad aluminum. Exception: For installations to supply only limited loads of a single branch circuit such as small polyphase power, controlled water heaters. and the like, they shall not be smaller than No. 12 hard-drawn copper or equivalent. (c) Grounded Conductors. The grounded conductor shall not be less than the minimum size as required by Section 250-23(b). 230-24. Clearances. The vertical clearances of all service-drop conductors shall be based on conductor temperature of 60°F (15°C), no wind, with final unloaded sag in the wire, conductor, or cable. 70-74 NATIONAL ELECTRICAL CODE Service-drop conductors shall not be readily accessible and shall comply with (a) through (d) below for services not over 600 volts, nominal. (a) Above Roofs. Conductors shall have a vertical clearance of not less than 8 feet (2.44 m) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance not less than 3 feet (914 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 Section 230-24(b). Exception No. 2: Where the voltage between conductors does not exceed 300 and the roof has a slope of not less than 4 inches (102 mm) in 12 inches (305 mm), a reduction in clearance to 3 feet (914 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 18 inches (457 mm) shall be permitted if (1) not more than 6 feet (1.83 m) of service-drop conductors, 4 feet (1.22 m) horizontally, pass above the roof overhang, and (2) they are terminated at a through-the-roof raceway or approved support. (FPN): See Section 230-28 for mast supports. Exception No. 4: The requirement for maintaining the vertical clearance 3 feet (914 mm) from the edge of the roof shall not apply to the final conductor span where the service drop is attached to the side of a building. (b) Vertical Clearance from Ground. Service-drop conductors where not in excess of 600 volts, nominal, shall have the following minimum clearance from final grade. 10 feet (3.05 m) - at the electric service entrance to buildings, or at the drip loop of the building electric entrance, or above areas or sidewalks accessible only to pedestrians, measured from final grade or other accessible surface only for service-drop cables supported on and cabled together with a grounded bare messenger and limited to 150 volts to ground. 12 feet (3.66 m) - over residential property and driveways, and those commercial areas not subject to truck traffic where the voltage is limited to 300 volts to ground. 15 feet (4.57 m) - for those areas listed in the 12-foot (3.66-m) classification where the voltage exceeds 300 volts to ground. 18 feet (5.49m) - 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. (c) Clearance from Building Openings. See Section 230-9. (d) Clearance from Swimming Pools. See Section 680-8. 230-26. Point of Attachment. The point of attachment of the service-drop conductors to a building or other structure shall provide the minimum clearances as specified in Section 230-24. In no case shall this point of attachment be less than 10 feet (3.05 m) above finished grade. ARTICLE 230 - SERVICES 70-75 230-27. Means of Attachment. Multiconductor cables used for service drops shall be attached to buildings or other structures by fittings identified for use with service conductors. Open conductors shall be attached to fittings identified for use with service conductors or to noncombustible, nonabsorbent insulators securely attached to the building or other structure. 230-28. Service Masts as Supports. Where a service mast is used for the support of service-drop conductors, it shall be of adequate strength or be supported by braces or guys to withstand safely the strain imposed by the service drop. Where raceway-type service masts are used, all raceway fittings shall be identified for use with service masts. (FPN): It is the intent of this section to allow only power service-drop conductors to be attached to a service mast. 230-29. Supports Over Buildings. Service-drop conductors passing over a roof shall be securely supported by substantial structures. Where practicable, such supports shall be independent of the building. C. Underground Service-Lateral Conductors 230-30. Insulation. Service-lateral conductors shall withstand exposure to atmospheric and other conditions of use without detrimental leakage of current. Service-lateral conductors shall be insulated for the applied voltage. Exception: A grounded conductor shall be permitted to be uninsulated as follows: a. Bare copper used in a raceway. b. Bare copper for direct burial where bare copper is judged to be suitable for the soil conditions. C. Bare copper for direct burial without regard to soil conditions where part of a cable assembly identified for underground use. d. Aluminum or copper-clad aluminum without individual insulation or covering where part of a cable assembly identified for underground use in a raceway or for direct burial. 230-31. Size and Rating. (a) General. Service-lateral conductors shall have sufficient ampacity to carry the current for the load as computed in accordance with Article 220 and shall have adequate mechanical strength. (b) Minimum Size. The conductors shall not be smaller than No. 8 copper or No. 6 aluminum or copper-clad aluminum. Exception: For installations to supply only limited loads of a single branch circuit such as small polyphase power, controlled water heaters and the like, they shall not be smaller than No. 12 copper or No. 10 aluminum or copper-clad aluminum. (c) Grounded Conductors. The grounded conductor shall not be less than the minimum size required by Section 250-23(b). (FPN): Reasonable efficiency of operation can be provided when voltage drop is taken into consideration in sizing the service-lateral conductors. 70-76 NATIONAL ELECTRICAL CODE 230-32. Protection Against Damage. Underground service-lateral conductors shall be protected against damage in accordance with Section 300-5. Service-lateral conductors entering a building shall be installed in accordance with Section 230-6 or protected by a raceway wiring method identified in Section 230-43. D. Service-Entrance Conductors 230-40. Number of Service-Entrance Conductor Sets. Each service drop or lateral shall supply only one set of service-entrance conductors. Exception No. 1: Buildings with more than one occupancy shall be permitted to have one set of service-entrance conductors run to each occupancy or to a group of occupancies. Exception No. 2: Where two to six service disconnecting means in separate enclosures are grouped at one location and supply separate loads from one service drop or lateral, one set of service-entrance conductors shall be permitted to supply each or several such service equipment enclosures. 230-41. Insulation of Service-Entrance Conductors. Service-entrance conductors shall normally withstand exposure to atmospheric and other conditions of use without detrimental leakage of current. Service-entrance conductors entering or on the exterior of buildings or other structures shall be insulated. Exception: A grounded conductor shall be permitted to be uninsulated as follows: a. Bare copper used in a raceway or part of a service cable assembly. b. Bare copper for direct burial where bare copper is judged to be suitable for the soil conditions. C. Bare copper for direct burial without regard to soil conditions where part of a cable assembly identified for underground use. d. Aluminum or copper-clad aluminum without individual insulation or covering where part of a cable assembly or identified for underground use in a raceway or for direct burial. 230-42. Size and Rating. (a) General. Service-entrance conductors shall be of sufficient size to carry the loads as computed in Article 220. Ampacity shall be determined from Section 310-15. Exception: The maximum allowable current of approved busways shall be that value for which the busway has been listed or labeled. (b) Ungrounded Conductors. Ungrounded conductors shall have an ampacity of not less than: (1) 100 amperes, 3-wire for a service to a one-family dwelling with six or more 2-wire branch circuits. (2) 100 amperes, 3-wire for a service to a one-family dwelling with an initial net computed load of 10 kVA or more. ARTICLE 230 - SERVICES 70-77 (3) 60 amperes for other loads. Exception No. 1: For loads consisting of not more than two 2-wire branch circuits, No. 8 copper or No. 6 aluminum or copper-clad aluminum. Exception No. 2: By special permission, for loads limited by demand or by the source of supply, No. 8 copper or No. 6 aluminum or copper-clad aluminum. Exception No. 3: For limited loads of a single branch circuit, No. 12 copper or No. 10 aluminum or copper-clad aluminum, but in no case smaller than the branch-circuit conductors. (c) Grounded Conductors. The grounded conductor shall not be less than the minimum size as required by Section 250-23(b). 230-43. Wiring Methods for 600 Volts, Nominal, or Less. Serviceentrance conductors shall be installed in accordance with the applicable requirements of this Code covering the type of wiring method used and limited to the following methods: (1) open wiring on insulators; (2) rigid metal conduit; (3) intermediate metal conduit; (4) electrical metallic tubing; (5) service-entrance cables; (6) wireways; (7) busways; (8) auxiliary gutters; (9) rigid nonmetallic conduit; (10) cablebus; (11) Type MC cable; (12) mineral-insulated, metal-sheathed cable; (13) flexible metal conduit or liquidtight flexible metal conduit not over 6 feet (1.83 m) long between raceways, or between raceway and service equipment, with equipment bonding jumper routed with the flexible metal conduit according to provisions of Section 250-79(a), (c), (d), and (f); or (14) liquidtight flexible nonmetallic conduit. Approved cable tray systems shall be permitted to support cables approved for use as service-entrance conductors. 230-46. Unspliced Conductors. Service-entrance conductors shall not be spliced. Exception No. 1: Clamped or bolted connections in metering equipment enclosures shall be permitted. Exception No. 2: Where service-entrance conductors are tapped to supply two to six disconnecting means grouped at a common location. Exception No. 3: At a properly enclosed junction point where an underground wiring method is changed to another type of wiring method. Exception No. 4: A connection shall be permitted where service conductors are extended from a service drop to an outside meter location and returned to connect to the service-entrance conductors of an existing installation. Exception No. 5: Where the service-entrance conductors consist of busway, connections shall be permitted as required to assemble the various sections and fittings. 230-49. Protection Against Physical Damage - Underground. Underground service-entrance conductors shall be protected against physical damage in accordance with Section 300-5. 70-78 NATIONAL ELECTRICAL CODE 230-50. Protection of Open Conductors and Cables Against Damage - Aboveground. Service-entrance conductors installed aboveground shall be protected against physical damage as specified in (a) or (b) below. (a) Service-Entrance Cables. Service-entrance cables, where subject to physical damage, such as where installed in exposed places near sidewalks, walkways, driveways, or coal chutes, or where subject to contact with awnings, shutters, swinging signs, or similar objects, shall be protected in any of the following ways: (1) by rigid metal conduit; (2) by intermediate metal conduit; (3) by rigid nonmetallic conduit suitable for the location; (4) by electrical metallic tubing; or (5) by other approved means. (b) Other than Service-Entrance Cable. Individual open conductors and cables other than service-entrance cables shall not be installed within 10 feet (3.05 m) of grade level or where exposed to physical damage. Exception: Type MI and Type MC cable shall be permitted within 10 feet (3.05 m) of grade level where not exposed to physical damage or where protected in accordance with Section 300-5(d). 230-51. Mounting Supports. Cables or individual open service conductors shall be supported as specified in (a), (b), or (c) below. (a) Service-Entrance Cables. Service-entrance cables shall be supported by straps or other approved means within 12 inches (305 mm) of every service head, gooseneck, or connection to a raceway or enclosure and at intervals not exceeding 30 inches (762 mm). (b) Other Cables. Cables that are not approved for mounting in contact with a building or other structure shall be mounted on insulating supports installed at intervals not exceeding 15 feet (4.57 m) and in a manner that will maintain a clearance of not less than 2 inches (50.8 mm) from the surface over which they pass. (c) Individual Open Conductors. Individual open conductors shall be installed in accordance with Table 230-51(c). Where exposed to the weather, the conductors shall be mounted on insulators or on insulating supports attached to racks, brackets, or other approved means. Where not exposed to the weather, the conductors shall be mounted on glass or porcelain knobs. 230-52. Individual Conductors Entering Buildings or Other Structures. Where individual open conductors enter a building or other structure, they shall enter through roof bushings or through the wall in an upward slant through individual, noncombustible, nonabsorbent insulating tubes. Drip loops shall be formed on the conductors before they enter the tubes. 230-53. Raceways to Drain. Where exposed to the weather, raceways enclosing service-entrance conductors shall be raintight and arranged to drain. Where embedded in masonry, raceways shall be arranged to drain. Exception: As permitted in Section 350-2. ARTICLE 230 - SERVICES 70-79 Table 230-51(c). Supports and Clearances for Individual Open Service Conductors Minimum Clearances In Inches Maximum Distance Maximum in Feet Between From Volts Between Supports Conductors Surface 600 9 6 2 600 15 12 2 300 4½ 3 2 600* 41/2* 2½* 1* For SI units: one inch = 25.4 millimeters; one foot = 0.3048 meter. *Where not exposed to weather. 230-54. Connections at Service Head. (a) Raintight Service Head. Service raceways shall be equipped with a raintight service head at the point of connection to service-drop conductors. (b) Service Cable Equipped with Raintight Service Head or Gooseneck. Service cables, either (1) unless continuous from pole to service equipment or meter, shall be equipped with a raintight service head, or (2) shall be formed in a gooseneck and taped and painted or taped with a self-sealing, weather-resistant thermoplastic. (c) Service Heads Above Service-Drop Attachment. Service heads, and goosenecks in service-entrance cables, shall be located above the point of attachment of the service-drop conductors to the building or other structure. Exception: Where it is impracticable to locate the service head above the point of attachment, the service head location shall be permitted not farther than 24 inches (610 mm) from the point of attachment. (d) Secured. Service cables shall be held securely in place. (e) Separately Bushed Openings. Service heads shall have conductors of different potential brought out through separately bushed openings. (f) Drip Loops. Drip loops shall be formed on individual conductors. To prevent the entrance of moisture, service-entrance conductors shall be connected to the service-drop conductors either (1) below the level of the service head, or (2) below the level of the termination of the serviceentrance cable sheath. (g) Arranged that Water Will Not Enter Service Raceway or Equipment. Service-drop conductors and service-entrance conductors shall be arranged so that water will not enter service raceway or equipment. 230-55. Termination at Service Equipment. Any service raceway or cable shall terminate at the inner end in a box, cabinet, or equivalent fitting that effectively encloses all energized metal parts. Exception: Where the service disconnecting means is mounted on a switchboard having exposed busbars on the back, a raceway shall be permitted to terminate at a bushing. 70-80 NATIONAL ELECTRICAL CODE 230-56. Service-Entrance Conductor with the Higher Voltage-to-Ground. On a 4-wire delta-connected service where the midpoint of one phase is grounded, the service-entrance conductor 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. E. Service Equipment - General 230-62. Service Equipment - Enclosed or Guarded. Energized parts of service equipment shall be enclosed as specified in (a) below, or guarded as specified in (b) below. (a) Enclosed. Energized parts shall be enclosed so that they will not be exposed to accidental contact or guarded as in (b) below. (b) Guarded. Energized parts that are not enclosed shall be installed on a switchboard, panelboard, or control board and guarded in accordance with Sections 110-17 and 110-18. Such an enclosure shall be provided with means for locking or sealing doors providing access to energized parts. 230-63. Grounding and Bonding. Service equipment, raceways, cable armor, cable sheaths, etc., and any service conductor that is to be grounded shall be grounded in accordance with the following parts of