1910.303(c): Electrical Connections, Terminals and Splices
Connectors and lugs must be identified for the conductor material and properly installed, and dissimilar metals such as copper and aluminum may not be mixed in a connector unless it is identified for that use. Terminal connections must be good without damaging conductors, and splices must use identified devices or brazing, welding or soldering, with all splices and free ends insulated equal to the conductors.
Key takeaways
- 1910.303(c) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart S).
- OSHA cited it 56 times in the last 3 years, in 56 inspections, with $153,143 in current penalties.
- 1 death is linked to inspections that cited this rule.
- Most citations: PR (9), VA (5), GA (5).
- Related part: 1910.303(c)(3) Splices (52 citations).
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In this article
What this rule covers
29 CFR 1910.303(c) ("Electrical connections") is one requirement inside 1910.303 General, an OSHA general industry standard (Part 1910, Subpart S). It includes 10 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
(c) Electrical connections — 56 citations
(1) General. Because of different characteristics of dissimilar metals:
(i) Devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used;
(ii) Conductors of dissimilar metals may not be intermixed in a terminal or splicing connector where physical contact occurs between dissimilar conductors (such as copper and aluminum, copper and copper-clad aluminum, or aluminum and copper-clad aluminum) unless the device is identified for the purpose and conditions of use; and
(iii) Materials such as solder, fluxes, inhibitors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, installation, or equipment.
(2) Terminals. 2 citations
(i) Connection of conductors to terminal parts shall ensure a good connection without damaging the conductors and shall be made by means of pressure connectors (including set-screw type), solder lugs, or splices to flexible leads. However, No. 10 or smaller conductors may be connected by means of wire binding screws or studs and nuts having upturned lugs or equivalent. 2 citations
(ii) Terminals for more than one conductor and terminals used to connect aluminum shall be so identified.
(3) Splices. Open (c)(3) 52 citations
(i) Conductors shall be spliced or joined with splicing devices identified for the use or by brazing, welding, or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined to be mechanically and electrically secure without solder and then soldered. All splices and joints and the free ends of conductors shall be covered with an insulation equivalent to that of the conductors or with an insulating device identified for the purpose. Open (c)(3)(i) 51 citations
(ii) Wire connectors or splicing means installed on conductors for direct burial shall be listed for such use. 1 citations
Source: eCFR, text current as of 2026-10-15. Read all of 1910.303.
Export the list: 56 inspections cited 1910.303(c) in the last 3 years, with employer, location, penalty and date.
Purple Belt, $59/moInjuries linked to this rule
1 death is linked to inspections where OSHA cited 1910.303(c).
At 9:00 a.m. on January 19, 2024, two employees (Employee #1 and Employee #2) were setting up the site to create another stack of steel pipes (30 inches in diameter by 40 feet long, weighing over 2,000 pounds each.) The employees removed the chock block…
Where and how often it was cited
| Year | Citations |
|---|---|
| 2023 | 4 |
| 2024 | 19 |
| 2025 | 28 |
| 2026 | 5 |
Top states: PR (9), VA (5), GA (5), TX (4), FL (4)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| THE GOODYEAR TIRE & RUBBER COMPANY | DANVILLE, VA | $13,415 |
| AEE | YAUCO, PR | $11,823 |
| CARL'S DONUTS, INC. | LAS VEGAS, NV | $10,046 |
| EMPRESAS V�ZQUEZ CORP. | VEGA ALTA, PR | $8,038 |
| C&C DFM- PBEM TRAFFIC ELECTRICAL MAINTENANCE SERVICES BRANCH | PEARL CITY, HI | $7,035 |
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OSHA interpretation letters
None exist. OSHA has not published a letter of interpretation for 1910.303(c).
Related parts of this rule
- 1910.303(c)(3) Splices 52 citations
- 1910.303(c)(3)(i) 51 citations
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Frequently asked questions
Can copper and aluminum be joined in the same connector?
Only if the device is identified for the purpose and conditions of use.
How must soldered splices be made?
They must first be spliced to be mechanically and electrically secure without solder, then soldered.
Do splices need insulation?
Yes. All splices, joints and free ends must be covered with insulation equivalent to the conductors or an identified insulating device.
About this page
Sources
- 29 CFR 1910.303 (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 2026-11-06
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.