Environmental deterioration requirements

No — under 1926.432(a)(1)(i) conductors or equipment that are not identified for use in damp or wet environments must not be located in damp or wet locations.

• Use only equipment and conductors that the manufacturer identifies or lists for damp/wet location use, or protect equipment so the operating environment is dry.
• If temporary wiring or equipment must be used outdoors or in a wet area during construction, provide enclosures, conduit, weatherproof fittings, or use equipment rated for wet locations to comply with 1926.432(a)(1)(i).

Conductors or equipment must not be located where they will be exposed to chemical agents that cause deterioration unless they are identified for that environment, per 1926.432(a)(1)(ii).

• Common examples of deteriorating agents include corrosive industrial gases or vapors (acid fumes, chlorinated solvents), caustic liquids, hydrocarbons, sewage gases, and oily mists.
• If exposure to these agents is possible, use equipment and materials listed for corrosive environments, provide protective enclosures, or relocate wiring to areas not exposed to the agents to meet 1926.432(a)(1)(ii).

You must not place conductors or equipment in areas with temperatures higher than their design ratings unless the equipment is identified for that environment, as required by 1926.432(a)(1)(iii).

• The standard does not set a numeric temperature limit; instead, use the temperature ratings supplied by the equipment or conductor manufacturer and industry listings.
• Where high ambient or localized heat (near furnaces, ovens, hot piping) exists, select wiring insulation, conduit, and devices rated for those temperatures or provide thermal barriers so the installation complies with 1926.432(a)(1)(iii).

Control equipment, utilization equipment, and busways approved for dry locations must be protected against weather damage during construction, per 1926.432(a)(2).

• Practical protections include installing temporary weatherproof enclosures, using weatherproof covers, routing through sealed conduit, elevating equipment above expected water levels, or postponing installation until dry conditions exist.
• The protection must keep the equipment dry and prevent exposure to wind-driven rain, melting snow, or other weather that could cause deterioration or electrical hazards in violation of 1926.432(a)(2).

Metal raceways, cable armor, boxes, sheathing, cabinets, fittings, supports, and hardware must be made of materials appropriate for the installation environment, according to 1926.432(b).

• "Appropriate" materials can include stainless steel, corrosion-resistant alloys, properly coated or galvanized steel, nonmetallic conduit, or other materials listed for the expected corrosive conditions.
• Select materials based on the environment (marine, chemical, acidic soils, high humidity) and manufacturer/industry guidance so the installation meets 1926.432(b).

Galvanized steel may be acceptable only if it is appropriate for the specific coastal conditions and expected corrosion exposure, per 1926.432(b).

• In many coastal environments, the salt air accelerates corrosion and may require higher-grade materials (stainless steel, special coatings, or nonmetallic raceways).
• Evaluate the exact exposure, consult manufacturer data and industry corrosion guidance, and choose materials that are appropriate for those conditions to comply with 1926.432(b).

No — temporary wiring or equipment not identified for the operating environment cannot be left exposed to dampness, corrosive agents, or excessive temperatures, under 1926.432(a)(1).

• Temporary installations must use components rated for the specific environmental hazards or be protected with enclosures, conduit, weatherproof fittings, or barriers.
• For equipment labeled "for dry locations only," provide weather protection during construction as required by 1926.432(a)(2).

Equipment is "identified for use in the operating environment" by its listing, labeling, or manufacturer documentation indicating suitability for that environment, and the employer must verify that suitability under 1926.432(a)(1).

• Check manufacturer markings, data sheets, and listings (e.g., UL listings) to confirm the environment (damp, wet, corrosive, high temperature) for which the device is approved.
• Employers are responsible for assessing hazards and selecting appropriate equipment; see OSHA's guidance on employer hazard assessment responsibilities in the PPE hazard assessment interpretation (2024-03-28) when verifying suitability for the worksite.

If corrosion makes the components inappropriate for the environment, they must be replaced or repaired with suitable materials so the installation complies with 1926.432(b).

• Corroded hardware can compromise mechanical support and electrical continuity; replace with corrosion-resistant materials or protective coatings when necessary.
• Document corrective action and ensure the replacement materials are appropriate for the remaining service conditions to meet 1926.432(b).

You can use temporary coverings only if they adequately protect dry-location equipment from weather during construction so it is not exposed, as required by 1926.432(a)(2).

• Simple plastic sheeting may be acceptable short-term if it prevents rain, snow, and prolonged damp conditions and is secured to prevent wind intrusion.
• For longer exposures or where severe weather is expected, use weatherproof enclosures or delay installation until dry conditions exist to remain compliant with 1926.432(a)(2).

Select cable sheathing, armor, boxes, and supports made of materials rated for the specific chemical exposures present, in accordance with 1926.432(b).

• Identify the chemicals, their concentrations, temperatures, and exposure frequency.
• Choose compatible materials (chemically resistant polymers, stainless alloys, special coatings) based on manufacturer chemical-resistance data so the installation meets 1926.432(b).

The environmental-deterioration standard itself does not mandate a written hazard assessment, but employers are responsible for assessing jobsite hazards and selecting appropriate protections; this responsibility is supported by OSHA guidance on employer hazard assessments in the PPE hazard assessment interpretation (2024-03-28).

• Use manufacturer documentation and site evaluations to determine whether equipment is identified for the operating environment per 1926.432(a)(1).
• Even when not specifically required by the text of 1926.432, documenting hazard evaluations is a best practice to support compliance and safe selection of materials.

Yes — busways are listed among items that must be of materials appropriate for the environment where they will be installed under 1926.432(b).

• Select busways with enclosures, finishes, and support materials rated for the site conditions (humidity, chemical exposure, salt air, etc.).
• Follow manufacturer specifications and industry standards for busway selection so the busway and its supports meet 1926.432(b).

Yes, provided the weatherproof cabinet (or other protective enclosure) maintains a dry operating environment for the equipment and the cabinet is rated for outdoor conditions; this approach complies with the intent of 1926.432(a)(1) and 1926.432(a)(2).

• Ensure the enclosure is properly sealed, ventilated as required, and rated (e.g., NEMA/IEC) for the weather and temperature conditions encountered.
• Verify that the cabinet does not trap excessive heat or corrosive vapors that would make the equipment unsuitable per 1926.432(a)(1)(iii).

Yes — nonmetallic raceways can be appropriate corrosion-resistant options if they are suitable for the electrical, mechanical, and environmental conditions, as required by 1926.432(b).

• Use nonmetallic conduits and fittings specifically rated for the application (UV resistance, temperature range, mechanical protection, chemical resistance).
• Confirm the chosen nonmetallic materials meet electrical code requirements and are appropriate for the environment to comply with 1926.432(b).

Yes — excessive ambient heating from sunlight or other sources can make a location unsuitable for equipment not rated for those temperatures, so you must use equipment identified for those conditions or protect it, per 1926.432(a)(1)(iii).

• Consider ventilated or reflective enclosures, shading, or selecting higher-temperature-rated components when solar heating will raise internal enclosure temperatures.
• Ensure the final installation complies with the manufacturer's temperature ratings and 1926.432(a)(1)(iii).

Yes — support hardware and fasteners must also be of materials appropriate for the environment, per 1926.432(b).

• Using a corrosion-resistant raceway with ordinary (corrodible) supports can still lead to premature failure; choose fasteners and supports (stainless, coated, or otherwise protected) compatible with the environment.
• Ensure the entire assembly (raceway, supports, clamps, anchors) is appropriate for the site to meet 1926.432(b).

You should replace or remediate corroded electrical components with materials appropriate for the environment so the installation complies with 1926.432(b).

• Evaluate the cause (weather exposure, aggressive atmosphere) and correct the deficiency with suitable materials or protective measures.
• Keep records of corrective actions and verify the repaired or replaced items meet manufacturer ratings and the requirements of 1926.432.

Yes — conductors and equipment, including portable tools and extension cords, must be suitable for the location and not placed where they would be exposed to dampness, corrosive agents, or excessive temperatures unless identified for those conditions, under 1926.432(a)(1).

• Use only cords and portable equipment rated for outdoor/damp use when they will be exposed to such conditions (look for appropriate markings and ratings).
• Protect temporary power runs with weatherproof fittings, elevated routing, or conduit to meet the requirements of 1926.432(a)(1).

Paints and coatings can be acceptable corrosion protections if they are specified for the expected exposure and applied/maintained correctly, consistent with 1926.432(b).

• Choose coatings rated for the chemicals, temperatures, and weather the installation will encounter and follow application and maintenance guidance.
• If coatings are likely to fail in the environment, select inherently corrosion-resistant materials instead to comply with 1926.432(b).