How do 2023 NEC updates protect wiring in agricultural buildings from rodent damage?

547.26 Physical Protection 

Overview 

Agricultural buildings and adjacent structures must contend with pest infestations, particularly from rodents and other small animals that are difficult to detect. These pests pose significant risks to electrical wiring as they can remove the insulation from nonmetallic cables by biting and tearing it off. The 2023 NEC updates in Section 547.26 address these challenges by prohibiting the concealment of nonmetallic cables within walls and ceilings of buildings near livestock areas. This measure prevents rodent damage to cables in hidden locations, reducing the risk of fire hazards and electrical failures. By implementing these enhanced protective requirements, the NEC promotes the safety, reliability, and functionality of electrical wiring in agricultural environments.

Applying the 2023 Code 

Agricultural buildings and adjacent structures are essential for farming operations, serving as storage for equipment, housing for livestock, and spaces for processing agricultural products. However, these buildings face unique challenges due to their operational environments. They are often exposed to harsh weather conditions, physical wear and tear from machinery and livestock, and infestations by pests such as rodents. These factors increase the risk of damage to electrical systems, which can lead to fire hazards, electrical shocks, and operational disruptions. Protecting and maintaining the integrity of electrical wiring in these buildings is crucial for maintaining safety and functionality. 

Section 547.5(E) of previous NEC versions required all electrical wiring and equipment in agricultural buildings to be protected from physical damage. This provision aimed to safeguard electrical systems from the physical and environmental threats typical in agricultural settings. In the 2023 NEC version, this section has been relocated to Section 547.26 and enhanced with additional requirements. The updated section prohibits nonmetallic cables from being concealed within walls and ceilings of buildings or portions thereof that are contiguous or physically adjoined to livestock confinement areas. An informational note has also been added to emphasize that rodents and other pests frequently damage nonmetallic cables by chewing through the insulation, which can lead to insulation failure and create fire hazards. These changes provide more comprehensive protection of electrical installations in agricultural buildings, enhancing the overall safety and reliability of electrical wiring in agricultural settings. 

What’s New for the 2023 NEC? 

The comparison of 2020 NEC Section 547.5(E) and 2023 NEC Section 547.26 is given in the Table below.