Article 547 Agricultural Buildings
- Poultry and animal excrement may cause corrosive vapors.
- Corrosive particles may combine with water.
- The area is damp and wet by reason of periodic washing for cleaning and sanitizing with water and cleansing agents.
- Similar conditions exist.
Equipotential Plane (as applied to agricultural buildings). An area where wire mesh or other conductive elements are embedded in or placed under concrete, bonded to all metal structures and fixed nonelectrical equipment that could become energized, and connected to the electrical grounding system to minimize voltage differences within the plane and between the planes, the grounded equipment, and the earth.
Informational Note No. 2: Aluminum and magnetic ferrous materials may corrode in agricultural environments.
Any existing agricultural building or structure for other than livestock and any existing buildings and structures not under the scope of Article 547 shall be permitted to be supplied in accordance with 250.32(B)(1) Exception No. 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.
- The equipment grounding conductor is connected to the grounded circuit conductor and the site-isolating device enclosure at the distribution point.
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 service and feeder conductors to limit voltage drop to 2 percent, and connecting loads line-to-line.
Informational Note No. 1: Methods to establish equipotential planes are described in American Society of Agricultural and Biological Engineers (ASABE) EP473.2-2001 (R2015), Equipotential Planes in Animal Containment Areas.
Informational Note No. 2: Methods for safe installation of livestock waterers are described in American Society of Agricultural and Biological Engineers (ASABE) EP342.3-2010 (R2015), Safety for Electrically Heated Livestock Waterers.