Article 547

Agricultural Buildings

  1. Scope. The provisions of this article shall apply to the following agricultural buildings or that part of a building or adjacent areas of similar or like nature as specified in 547.1(A) or (B).
    1. Excessive Dust and Dust with Water. Agricultural build‐ ings where excessive dust and dust with water may accumulate, including all areas of poultry, livestock, and fish confinement systems, where litter dust or feed dust, including mineral feed particles, may accumulate.
    2. Corrosive Atmosphere. Agricultural buildings where a corrosive atmosphere exists. Such buildings include areas where the following conditions exist:
    1. Poultry and animal excrement may cause corrosive vapors.
    2. Corrosive particles may combine with water.
    3. The area is damp and wet by reason of periodic washing for cleaning and sanitizing with water and cleansing agents.
    4. Similar conditions exist.
  2. Definitions.Distribution Point. An electrical supply point from which serv‐ ice drops, service conductors, feeders, or branch circuits to buildings or structures utilized under single management are supplied.Informational Note No. 1: Distribution points are also known as the center yard pole, meterpole, or the common distribution point.Informational Note No. 2: The service point as defined in Arti‐ cle 100 is typically at the distribution point.Equipotential Plane. An area where wire mesh or other conductive elements are embedded in or placed under concrete, bonded to all metal structures and fixed nonelectri‐ cal equipment that may become energized, and connected to the electrical grounding system to minimize voltage differences within the plane and between the planes, the grounded equip‐ ment, and the earth.Site-Isolating Device. A disconnecting means installed at the distribution point for the purposes of isolation, system mainte‐ nance, emergency disconnection, or connection of optional standby systems.
  3. Other Articles. For buildings and structures not having conditions as specified in 547.1, the electrical installations shall be made in accordance with the applicable articles in this Code.
  4. Surface Temperatures. Electrical equipment or devices installed in accordance with the provisions of this article shall be installed in a manner such that they will function at full rating without developing surface temperatures in excess of the specified normal safe operating range of the equipment or device.
  5. Wiring Methods.
    1. Wiring Systems. Types UF, NMC, copper SE cables, jack‐ eted Type MC cable, rigid nonmetallic conduit, liquidtight flex‐ ible nonmetallic conduit, or other cables or raceways suitable for the location, with approved termination fittings, shall be the wiring methods employed. The wiring methods of Arti‐ cle 502, Part II, shall be permitted for areas described in 547.1(A).Informational Note: See 300.7, 352.44, and 355.44 for installa‐ tion of raceway systems exposed to widely different tempera‐ tures.
    2. Mounting. All cables shall be secured within 200 mm (8 in.) of each cabinet, box, or fitting. Nonmetallic boxes, fittings, conduit, and cables shall be permitted to be mounted directly to any building surface covered by this article without maintaining the 6 mm (1∕4 in.) airspace in accordance with 300.6(D).ARTICLE 547 — AGRICULTURAL BUILDINGS 547.9
    3. Equipment Enclosures, Boxes, Conduit Bodies, and Fittings.
      1. Excessive Dust. Equipment enclosures, boxes, conduit bodies, and fittings installed in areas of buildings where exces‐ sive dust may be present shall be designed to minimize the entrance of dust and shall have no openings (such as holes for attachment screws) through which dust could enter the enclo‐ sure.
      2. Damp or Wet Locations. In damp or wet locations, equip‐ ment enclosures, boxes, conduit bodies, and fittings shall be placed or equipped so as to prevent moisture from entering or accumulating within the enclosure, box, conduit body, or fitting. In wet locations, including normally dry or damp loca‐ tions where surfaces are periodically washed or sprayed with water, boxes, conduit bodies, and fittings shall be listed for use in wet locations and equipment enclosures shall be weather‐ proof.
      3. Corrosive Atmosphere. Where wet dust, excessive mois‐ ture, corrosive gases or vapors, or other corrosive conditions may be present, equipment enclosures, boxes, conduit bodies, and fittings shall have corrosion resistance properties suitable for the conditions.Informational Note No. 1: See Table 110.28 for appropriate enclosure type designations.Informational Note No. 2: Aluminum and magnetic ferrous materials may corrode in agricultural environments.
    4. Flexible Connections. Where necessary to employ flexible connections, dusttight flexible connectors, liquidtight flexible metal conduit, liquidtight flexible nonmetallic conduit, or flex‐ ible cord listed and identified for hard usage shall be used.
    5. Physical Protection. All electrical wiring and equipment subject to physical damage shall be protected.imageInformational Note: For further information on aluminum andcopper-clad aluminum conductors, see 250.120(B).
    6. Separate Equipment Grounding Conductor. Where an equipment grounding conductor is installed underground within a location falling under the scope of Article 547, it shall be insulated.
    7. Receptacles. All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations listed in (1) through (4) shall have ground-fault circuit-interrupter protection:
      1. Areas having an equipotential plane
      2. Outdoors
      3. Damp or wet locations
      4. Dirt confinement areas for livestock
  6. Switches, Receptacles, Circuit Breakers, Controllers, and Fuses. Switches, including pushbuttons, relays, and similar devices, receptacles, circuit breakers, controllers, and fuses, shall be provided with enclosures as specified in 547.5(C).
  7. Motors. Motors and other rotating electrical machinery shall be totally enclosed or designed so as to minimize the entrance of dust, moisture, or corrosive particles.
  8. Luminaires. Luminaires shall comply with 547.8(A) through (C).
    1. Minimize the Entrance of Dust. Luminaires shall be instal‐ led to minimize the entrance of dust, foreign matter, moisture, and corrosive material.
    2. Exposed to Physical Damage. Luminaires exposed to physical damage shall be protected by a suitable guard.
    3. Exposed to Water. Luminaires exposed to water from condensation, building cleansing water, or solution shall be listed for use in wet locations.
  9. Electrical Supply to Building(s) or Structure(s) from a Distribution Point. A distribution point shall be permitted to supply any building or structure located on the same premises. The overhead electrical supply shall comply with 547.9(A) and (B), or with 547.9(C). The underground electrical supply shall comply with 547.9(C).
    1. Site-Isolating Device. Site-isolating devices shall comply with 547.9(A)(1) through (A)(10).
      1. Where Required. A site-isolating device shall be installed at the distribution point where two or more buildings or struc‐ tures are supplied from the distribution point.
      2. Location. The site-isolating device shall be pole-mounted and be not less than the height above grade required by 230.24 for the conductors it supplies.
      3. Operation. The site-isolating device shall simultaneously disconnect all ungrounded service conductors from the prem‐ ises wiring.
      4. Bonding Provisions. The site-isolating device enclosure shall be connected to the grounded circuit conductor and the grounding electrode system.
      5. Grounding. At the site-isolating device, the system groun‐ ded conductor shall be connected to a grounding electrode system via a grounding electrode conductor.
      6. Rating. The site-isolating device shall be rated for the calculated load as determined by Part V of Article 220.
      7. Overcurrent Protection. The site-isolating device shall not be required to provide overcurrent protection.
      8. Accessibility. The site-isolating device shall be capable of being remotely operated by an operating handle installed at a readily accessible location. The operating handle of the site- isolating device, when in its highest position, shall not be more than 2.0 m (6 ft 7 in.) above grade or a working platform.
      9. Series Devices. An additional site-isolating device for the premises wiring system shall not be required where a site- isolating device meeting all applicable requirements of this section is provided by the serving utility as part of their service requirements.
      10. Marking. A site-isolating device shall be permanently marked to identify it as a site-isolating device. This marking shall be located on the operating handle or immediately adja‐ cent thereto.
    2. Service Disconnecting Means and Overcurrent Protection at the Building(s) or Structure(s). Where the service discon‐ necting means and overcurrent protection are located at the building(s) or structure(s), the requirements of 547.9(B)(1) through (B)(3) shall apply.
      1. Conductor Sizing. The supply conductors shall be sized in accordance with Part V of Article 220.
      2. Conductor Installation. The supply conductors shall be installed in accordance with the requirements of Part II of Arti‐ cle 225.
      3. Grounding and Bonding. For each building or structure, grounding and bonding of the supply conductors shall be in accordance with the requirements of 250.32, and the following conditions shall be met:
        1. The equipment grounding conductor is not smaller than the largest supply conductor if of the same material, or is adjusted in size in accordance with the equivalent size columns of Table 250.122 if of different materials.
        2. The equipment grounding conductor is connected to the grounded circuit conductor and the site-isolating device enclosure at the distribution point.
    3. Service Disconnecting Means and Overcurrent Protection at the Distribution Point. Where the service disconnecting means and overcurrent protection for each set of feeders or branch circuits are located at the distribution point, the feeders or branch circuits to buildings or structures shall comply with the provisions of 250.32 and Article 225, Parts I and II.Informational Note: Methods to reduce neutral-to-earth voltages in livestock facilities include supplying buildings or structures with 4-wire single-phase services, sizing 3-wire single-phase serv‐ ice and feeder conductors to limit voltage drop to 2 percent, and connecting loads line-to-line.
    4. Identification. Where a site is supplied by more than one distribution point, a permanent plaque or directory shall be installed at each of these distribution points denoting the loca‐ tion of each of the other distribution points and the buildings or structures served by each.
  10. Equipotential Planes and Bonding of Equipotential Planes. The installation and bonding of equipotential planes shall comply with 547.10(A) and (B). For the purposes of this section, the term livestock shall not include poultry.
  1. Where Required. Equipotential planes shall be installed where required in (A)(1) and (A)(2).
    1. Indoors. Equipotential planes shall be installed in confinement areas with concrete floors where metallic equip‐ ment is located that may become energized and is accessible to livestock.
    2. Outdoors. Equipotential planes shall be installed in concrete slabs where metallic equipment is located that may become energized and is accessible to livestock.The equipotential plane shall encompass the area where the livestock stands while accessing metallic equipment that may become energized.
  2. Bonding. Equipotential planes shall be connected to the

Biological Engineers (ASABE) EP473.2-2001, Equipotential Planes in Animal Containment Areas.

Informational Note No. 2: Methods for safe installation of live‐ stock waterers are described in American Society of Agricultural and Biological Engineers (ASABE) EP342.3-2010, Safety for Elec‐ trically Heated Livestock Waterers.

Informational Note No. 3: Low grounding electrode system resistances may reduce voltage differences in livestock facilities.