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547.9 Distribution Point Required for Livestock Agricultural Buildings and Structures

Revison

Change Summary

  • Any agricultural building or structure (intended for livestock) located on the same premises is now required to be supplied from a distribution point. More than one distribution point on the same premises is also permitted. The service disconnecting means and overcurrent protection for each set of feeders or branch circuits are required to be located at the distribution point. The service disconnecting means is required to be installed in accordance with Part VI of Article 230. The feeders or branch circuits supplied to buildings or structures shall comply with the provisions of 250.32 and Article 225, Parts I and II.
NEC® Text

547.9 Electrical Supply to Building(s) or Structure(s) from a Distribution Point.
A distribution point shall be permitted to supply Any agricultural building or structure for livestock located on the same premises shall be supplied from a distribution point. More than one distribution point on the same premises shall be permitted. 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).
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.
(A) Site-Isolating Device. (See NEC for complete Code text)
(B) Service Disconnecting Means and Overcurrent Protection at the Building(s) or Structure(s). (See NEC for complete Code text)
(C) 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 shall be located at the distribution point, the. The service disconnecting means shall be installed in accordance with Part VI of Article 230. The feeders or branch circuits supplied 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 service and feeder conductors to limit voltage drop to 2 percent, and connecting loads line-to-line. 

(D) 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 location of each of the other distribution points and the buildings or structures served by each.

Material taken from the National Electric Code® is reprinted with permission from NFPA 70®, 2020 edition.
National Electrical Code®, Copyright 2019, National Fire Protection Association, Quincy, MA. All rights reserved.

Expert Analysis

Many agricultural farms and locations consist of multiple buildings that are directly related to the overall agricultural operation. The requirements of 547.9 are to ensure there is a means to shut off all electrical power to the multiple buildings on the agricultural premises at a single location. At many agricultural farms across the USA, this single location will typically be located at the service point or “meter pole” or the “center yard pole.” The NEC refers to this point as the “distribution point.”

547.5(G) GFCI Protection in Agricultural Buildings

For the 2020 NEC, revisions to the parent text of 547.9 and to 547.9(C) will now “require” agricultural buildings and structures that are for livestock to be supplied from a common distribution point. This change will mandate that an agricultural building or structure that are for stocking, housing, maintaining, or feeding livestock will be supplied by a grounded four wire distribution to reduce stray voltages that may affect livestock. Revisions to 547.9(C) will now make this section clearer in mandating that branch circuits and feeders to agricultural buildings be supplied through a distribution point and overcurrent protection is required for all underground feeder and branch circuit installations. The four- wire distribution system is utilized here mainly for the purpose of helping with stray voltage on the farm. By having the fourth conductor (two ungrounded conductors, a grounded neutral conductor, and an equipment grounding conductor), the grounded (neutral) conductor is isolated from the equipment grounding conductor (not bonded) at other buildings past the first means of disconnect, to help eliminate circulating or stray currents.

The revised text at 547.9(C) also clarifies that for existing agricultural buildings and structures (other than livestock buildings such as for grain handling, poultry and fish containment systems) and for existing buildings or structures other than those covered under the scope of Article 547 (a house or machine shed on the premises) may be supplied in accordance with 250.32(B)(1)Ex. No. 1 permitting a three wire distribution for existing feeders to existing buildings.

 

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