1926.403(d): Mounting and Cooling Electrical Equipment
Employers must firmly secure electric equipment to the surface it is mounted on, and wooden plugs driven into holes in masonry, concrete, plaster or similar materials must not be used. Equipment cooled by natural air flow must be installed so walls or nearby equipment do not block air flow, floor-mounted equipment needs top clearance to dissipate warm air, and ventilating openings must not be obstructed.
Key takeaways
- 1926.403(d) is part of OSHA's construction standards (29 CFR Part 1926, Subpart K).
- OSHA cited it 25 times in the last 3 years, in 25 inspections, with $30,027 in current penalties.
- Most citations: VA (16), MD (2), AZ (1).
- Related part: 1926.403(d)(1) Mounting (25 citations).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1926.403(d) ("Mounting and cooling of equipment") is one requirement inside 1926.403 General requirements, an OSHA construction standard (Part 1926, Subpart K). It includes 2 sub-paragraphs. The official text below is copied word for word from the Electronic Code of Federal Regulations (eCFR). The numbers, injury cases and training on this page show how OSHA enforces it on real job sites.
Official text
(d) Mounting and cooling of equipment — 25 citations
(1) Mounting. Electric equipment shall be firmly secured to the surface on which it is mounted. Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials shall not be used. Open (d)(1) 25 citations
(2) Cooling. Electrical equipment which depends upon the natural circulation of air and convection principles for cooling of exposed surfaces shall be installed so that room air flow over such surfaces is not prevented by walls or by adjacent installed equipment. For equipment designed for floor mounting, clearance between top surfaces and adjacent surfaces shall be provided to dissipate rising warm air. Electrical equipment provided with ventilating openings shall be installed so that walls or other obstructions do not prevent the free circulation of air through the equipment.
Source: eCFR, text current as of 2026-10-15. Read all of 1926.403.
Where and how often it was cited
| Year | Citations |
|---|---|
| 2023 | 2 |
| 2024 | 5 |
| 2025 | 14 |
| 2026 | 4 |
Top states: VA (16), MD (2), AZ (1), IN (1), MA (1)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| N-TIER DISASTER RECOVERY SOLUTIONS | ABINGDON, VA | $4,291 |
| G J HOPKINS INC | BLACKSBURG, VA | $3,525 |
| S&S ELECTRICAL SERVICES, INC. | RICHMOND, VA | $2,970 |
| A.R. CHESSON CONSTRUCTION CO. | NEWPORT NEWS, VA | $2,885 |
| S.B. BALLARD CONSTRUCTION COMPANY | SUFFOLK, VA | $2,460 |
Free toolbox talk
A 5-minute crew talk on 1926.403(d), plus alerts when this rule changes. Free.
OSHA interpretation letters
None exist. OSHA has not published a letter of interpretation for 1926.403(d).
Related parts of this rule
- 1926.403(d)(1) Mounting 25 citations
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Frequently asked questions
Can wooden plugs be used to mount equipment in concrete?
No, wooden plugs driven into holes in masonry, concrete, plaster or similar materials shall not be used.
What is required for naturally cooled equipment?
It must be installed so room air flow over its surfaces is not prevented by walls or adjacent equipment.
What about ventilating openings?
Walls or other obstructions must not prevent free circulation of air through the equipment.
About this page
Sources
- 29 CFR 1926.403 (eCFR), text current as of 2026-10-15
- U.S. Department of Labor enforcement data: OSHA inspections, citations and accident records, copied nightly; data as of 2026-10-20
3-year window. Federal OSHA only; state-plan rules are not counted. Plain-language text is a summary, not legal advice; the official text controls. Black Belt Safety is not part of OSHA or the Department of Labor.