Article 100 Definitions. Corrosive Environment.

Areas where pool chemicals are stored are considered corrosive environments. Wiring methods in these locations shall be suitable for use in such areas. Type NM nonmetallic sheathed cable is NOT permitted in corrosive locations.
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Areas where pool chemicals are stored are considered corrosive environments. Wiring methods in these locations shall be suitable for use in such areas. Type NM nonmetallic sheathed cable is NOT permitted in corrosive locations.

Code Change Summary: A new definition of a “Corrosive Environment” was created.

In the 2023 NEC®, the previous definition of a “Corrosive Environment” found in Section 680.2 was reworded and moved to Article 100.

A corrosive environment includes areas or enclosures without adequate ventilation, where electrical equipment is installed and pool sanitation chemicals are stored, handled, or dispensed.

Certain areas around the pool can be highly corrosive to electrical wiring methods and materials. Chlorine and muriatic acid in the pool water can give off corrosive fumes that will eat away at the zinc coating on galvanized raceways and fittings. Often, architectural pits, sunken gazebos or bars are installed up against the wall of a pool to make a nice outdoor beverage or grilling area. These areas are often susceptible to splashing from those swimming in the pool. According to 680.12, equipment in these areas shall be suitable for the environment in accordance with 300.6.

Other areas or buildings associated with the pool might be used for acid or chlorine storage. These chemicals are extremely harsh for wiring methods and materials and special care should be taken to ensure proper protection of conductors and equipment installed in these areas.

Section 680.14 provides requirements for wiring methods and other equipment installed in corrosive environments.

The previous definition of a corrosive environment in Article 680 was vague and not very clear and the 2023 change to the definition still leaves a lot open to interpretation.

The revised definition still includes the word “area” which is not defined in the NEC®.

How far away must something be to not be considered in the “area” of something else?

The revised definition still includes the word “adequate” which is not defined in the NEC®. Since the 2014 NEC® code cycle, there has been an effort to gradually phase out subjective words such as “adequate”, “inadequate”, and “sufficient” from as many places as possible.

One of the public inputs contributing to this code change intended to have the term “corrosive environment” apply only to enclosed areas. The committee statement for this code change included a clarification that corrosive environments can be indoors or outdoors.

Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC® edition of NFPA 70.

2020 Code Language:

680.2 Definitions.

Corrosive Environment. Areas where pool sanitation chemicals are stored, handled, or dispensed, and confined areas under decks adjacent to such areas, as well as areas with circulation pumps, automatic chlorinators, filters, open areas under decks adjacent to or abutting the pool structure, and similar locations.

2023 Code Language:

Article 100 Definitions.

N Corrosive Environment. Areas or enclosures without adequate ventilation, where electrical equipment is located and pool sanitation chemicals are stored, handled, or dispensed. (680)

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Article 100 Definitions. Corrosive Environment.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Based on the 2023 NEC, which of the following is a corrosive environment?

A: A room with adequate ventilation, where electrical equipment is located.
B: An enclosure with adequate ventilation, where electrical equipment is located.
C: A place with adequate ventilation, where pool sanitation chemicals are stored.
D: Areas or enclosures without adequate ventilation, where electrical equipment is located and pool sanitation chemicals are stored, handled, or dispensed.
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