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CBO
Corrosive Environment
Definition (NEC 2023)
Areas or enclosures without adequate ventilation, where electrical equipment is located and pool sanitation chemicals are stored, handled, or dispensed. (680) (CMP-17)
Informational Note No. 1: See Advisory: Swimming Pool Chemical: Chlorine, OSWER 90-008.1, June 1990, available from the EPA National Service Center for Environmental Publications (NSCEP), as sanitation chemicals and pool water are considered to pose a risk of corrosion (gradual damage or destruction of materials) due to the presence of oxidizers (e.g., calcium hypochlorite, sodium hypochlorite, bromine, chlorinated isocyanurates) and chlorinating agents that release chlorine when dissolved in water.
Informational Note No. 2: See ANSI/APSP-11, Standard for Water Quality in Public Pools and Spas; ANSI/ASHRAE 62.1, Table 6-4 Minimum Exhaust Rates; and 2021 International Swimming Pool and Spa Code (ISPSC), Section 324, including associated definitions and requirements concerning adequate ventilation of indoor spaces such as equipment and chemical storage rooms, which can reduce the likelihood of the accumulation of corrosive vapors. Chemicals such as chlorine cause severe corrosive and deteriorating effects on electrical connections, equipment, and enclosures when stored and kept in the same vicinity.
Explanation
The NEC definition of “Corrosive Environment” in Article 680 highlights a condition that arises when pool sanitation chemicals are stored, handled, or dispensed in spaces that lack proper ventilation. These environments present a significant hazard to electrical equipment due to the presence of oxidizing agents such as chlorine and bromine, which, when combined with moisture, aggressively attack metals and electrical connections.
This definition is supported by informational notes pointing to federal and consensus standards. The EPA recognizes chlorine-based compounds and chlorinating agents as high-risk oxidizers that can cause gradual but severe material degradation. Similarly, ANSI/APSP-11, ASHRAE 62.1, and the ISPSC establish ventilation benchmarks to mitigate the accumulation of corrosive vapors in pool-related spaces. Without adherence to these standards, corrosion can accelerate, leading to failures in enclosures, conduits, fittings, and terminations, ultimately creating safety and reliability issues.
Relation to 680.14
Section 680.14 directly addresses wiring methods and equipment permitted in corrosive environments. The Code requires wiring methods to be suitable for use in such conditions. Acceptable wiring methods include rigid metal conduit (RMC), intermediate metal conduit (IMC), rigid polyvinyl chloride (PVC) conduit, reinforced thermosetting resin conduit (RTRC), and liquidtight flexible nonmetallic conduit. Aluminum conduit and tubing are specifically prohibited due to their susceptibility to attack in these environments.
In addition, equipment located in corrosive environments must either be inherently corrosion-resistant or installed in enclosures designed to provide corrosion protection. Equipment listed for pool and spa applications is automatically considered suitable.
Application
In practice, this means electrical rooms adjacent to pool equipment spaces, storage areas for chlorine tablets or liquid sodium hypochlorite, and indoor pump rooms must be carefully evaluated. Designers and inspectors should ensure not only that the wiring method complies with 680.14, but also that ventilation is provided per ASHRAE and ISPSC standards to reduce the corrosive atmosphere. Where ventilation is lacking, electrical components must be chosen with corrosion resistance in mind or housed in listed enclosures to ensure long-term safety and performance.
Definition (NEC 2023)
Areas or enclosures without adequate ventilation, where electrical equipment is located and pool sanitation chemicals are stored, handled, or dispensed. (680) (CMP-17)
Informational Note No. 1: See Advisory: Swimming Pool Chemical: Chlorine, OSWER 90-008.1, June 1990, available from the EPA National Service Center for Environmental Publications (NSCEP), as sanitation chemicals and pool water are considered to pose a risk of corrosion (gradual damage or destruction of materials) due to the presence of oxidizers (e.g., calcium hypochlorite, sodium hypochlorite, bromine, chlorinated isocyanurates) and chlorinating agents that release chlorine when dissolved in water.
Informational Note No. 2: See ANSI/APSP-11, Standard for Water Quality in Public Pools and Spas; ANSI/ASHRAE 62.1, Table 6-4 Minimum Exhaust Rates; and 2021 International Swimming Pool and Spa Code (ISPSC), Section 324, including associated definitions and requirements concerning adequate ventilation of indoor spaces such as equipment and chemical storage rooms, which can reduce the likelihood of the accumulation of corrosive vapors. Chemicals such as chlorine cause severe corrosive and deteriorating effects on electrical connections, equipment, and enclosures when stored and kept in the same vicinity.
Explanation
The NEC definition of “Corrosive Environment” in Article 680 highlights a condition that arises when pool sanitation chemicals are stored, handled, or dispensed in spaces that lack proper ventilation. These environments present a significant hazard to electrical equipment due to the presence of oxidizing agents such as chlorine and bromine, which, when combined with moisture, aggressively attack metals and electrical connections.
This definition is supported by informational notes pointing to federal and consensus standards. The EPA recognizes chlorine-based compounds and chlorinating agents as high-risk oxidizers that can cause gradual but severe material degradation. Similarly, ANSI/APSP-11, ASHRAE 62.1, and the ISPSC establish ventilation benchmarks to mitigate the accumulation of corrosive vapors in pool-related spaces. Without adherence to these standards, corrosion can accelerate, leading to failures in enclosures, conduits, fittings, and terminations, ultimately creating safety and reliability issues.
Relation to 680.14
Section 680.14 directly addresses wiring methods and equipment permitted in corrosive environments. The Code requires wiring methods to be suitable for use in such conditions. Acceptable wiring methods include rigid metal conduit (RMC), intermediate metal conduit (IMC), rigid polyvinyl chloride (PVC) conduit, reinforced thermosetting resin conduit (RTRC), and liquidtight flexible nonmetallic conduit. Aluminum conduit and tubing are specifically prohibited due to their susceptibility to attack in these environments.
In addition, equipment located in corrosive environments must either be inherently corrosion-resistant or installed in enclosures designed to provide corrosion protection. Equipment listed for pool and spa applications is automatically considered suitable.
Application
In practice, this means electrical rooms adjacent to pool equipment spaces, storage areas for chlorine tablets or liquid sodium hypochlorite, and indoor pump rooms must be carefully evaluated. Designers and inspectors should ensure not only that the wiring method complies with 680.14, but also that ventilation is provided per ASHRAE and ISPSC standards to reduce the corrosive atmosphere. Where ventilation is lacking, electrical components must be chosen with corrosion resistance in mind or housed in listed enclosures to ensure long-term safety and performance.
