1910.304(a): Identifying Grounded and Grounding Conductors
Employers must make sure grounded conductors and equipment grounding conductors are each identifiable and distinguishable from all other conductors. Grounded conductors must not be connected in a way that reverses designated polarity, and grounding terminals or grounding-type devices on receptacles, cord connectors and plugs may be used only for grounding.
Key takeaways
- 1910.304(a) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart S).
- OSHA cited it 29 times in the last 3 years, in 29 inspections, with $37,933 in current penalties.
- Most citations: OR (5), MI (3), NY (2).
- Related part: 1910.304(a)(2) Polarity of connections (27 citations).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1910.304(a) ("Use and identification of grounded and grounding conductors") is one requirement inside 1910.304 Wiring design and protection, an OSHA general industry standard (Part 1910, Subpart S). It includes 5 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
(a) Use and identification of grounded and grounding conductors — 29 citations
(1) Identification of conductors. Open (a)(1)
(i) A conductor used as a grounded conductor shall be identifiable and distinguishable from all other conductors.
(ii) A conductor used as an equipment grounding conductor shall be identifiable and distinguishable from all other conductors.
(2) Polarity of connections. No grounded conductor may be attached to any terminal or lead so as to reverse designated polarity. Open (a)(2) 27 citations
(3) Use of grounding terminals and devices. A grounding terminal or grounding-type device on a receptacle, cord connector, or attachment plug may not be used for purposes other than grounding. Open (a)(3) 2 citations
Source: eCFR, text current as of 2026-10-15. Read all of 1910.304.
Where and how often it was cited
| Year | Citations |
|---|---|
| 2023 | 1 |
| 2024 | 9 |
| 2025 | 10 |
| 2026 | 9 |
Top states: OR (5), MI (3), NY (2), PR (2), SC (2)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| LUCKY EAGLE CASINO | ROCHESTER, WA | $7,566 |
| WAL-MART ASSOCIATES INC | LAS VEGAS, NV | $7,493 |
| GASCO INDUSTRIAL CORP. | GURABO, PR | $6,951 |
| MACY'S, INC. | HONOLULU, HI | $4,573 |
| 76420 - CULPEPER OF ORANGEBURG LLC | ORANGEBURG, SC | $3,000 |
Free toolbox talk
A 5-minute crew talk on 1910.304(a), plus alerts when this rule changes. Free.
OSHA interpretation letters
- Covering for Grounded Contact Conductors on Overhead Traveling Crane Systems (Patrick E. Wall/DEP/GIE/Harvey/26611) (2015-06-29)
- Grounding requirements for equipment connected by cord and plug. (1999-12-21)
- Acceptable job-made extension cords. (1992-06-17)
Related parts of this rule
- 1910.304(a)(2) Polarity of connections 27 citations
- 1910.304(a)(3) Use of grounding terminals and devices 2 citations
- 1910.304(a)(1) Identification of conductors
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Frequently asked questions
Must the grounded conductor be marked?
Yes. It must be identifiable and distinguishable from all other conductors.
Can polarity be reversed?
No. A grounded conductor may not be attached to any terminal or lead so as to reverse designated polarity.
Can the grounding terminal be used for something else?
No. It may not be used for purposes other than grounding.
About this page
Sources
- 29 CFR 1910.304 (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 2026-10-22
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.