SIC 3621 — Motors and Generators
Official OSHA SIC Manual Definition
Establishments primarily engaged in manufacturing electric motors (except engine starting motors) and power generators; motor generator sets; railway motors and control equipment; and motors, generators, and control equipment for gasoline, electric, and oil-electric buses and trucks. Establishments primarily engaged in manufacturing turbo-generators are classified in Industry 3511; those manufacturing starting motors and battery charging generators for internal combustion engines are classified in Industry 3694; and those manufacturing generators for welding equipment are classified in Industry 3548.
Description & Classification
SIC code 3621 representing 'Motors and Generators' is an industry category in the Standard Industrial Classification (SIC) system under U.S. OSHA and Federal procurement registers.
Modern NAICS Crosswalk
Trace the modern equivalent classifications in the 2022 North American Industry Classification System (NAICS) database:
- NAICS 335312 - Motor and Generator Manufacturing (via SIC1987:3621→NAICS1997:335312→2002:335312→2007:335312→2012:335312→2017:335312→2022:335312)
Classification Details
| SIC Code | 3621 |
|---|---|
| Industry Title | Motors and Generators |
| Division | Division D: Manufacturing |
| Major Group | Major Group 36: Electronic and Other Electrical Equipment and Components |
| JSON Endpoint | View as JSON · API → |
| Source / Verified | US Census 1987 SIC Concordance / 2026-08-08 |
SIC vs NAICS Compliance & Common Mismatches
Legacy SIC code 3621 classifies commercial operations based on primary end-product or service output under the 1987 federal framework. In contrast, modern 2022 NAICS codes group establishments based on production process inputs.
When submitting public disclosures to SEC EDGAR or determining OSHA workplace safety log recordkeeping exemptions (29 CFR Part 1904), rely strictly on the official OSHA 4-digit SIC classification rather than an automated commercial translation.
💡 Expert Guidance: SIC to NAICS Conversion
Common Compliance Mistake: Many contractors and B2B analysts confuse legacy 4-digit SIC codes like 3621 with modern 6-digit NAICS codes. Ensure that you use the correct active 2022 NAICS code (e.g. from the crosswalk below) when submitting representations on SAM.gov, as federal contracting officers only accept modern NAICS codes.
Related Pages & Tools
Further regulatory reference links for legacy SIC code 3621:
- SIC Codes Complete Compliance Guide — Detailed history and active legal applications of the SIC classification framework.
- Why Legacy SIC Codes Persist Guide — How credit systems and the SEC still rely on SIC metadata.
- SIC ↔ NAICS Crosswalk Tool — Trace industrial code conversions dynamically.
- SIC 3621 to NAICS Crosswalk — Bidirectional mapping to modern NAICS codes (Motors and Generators).
- SIC Major Group 36 Hub — View other legacy industries in this business division.
Frequently Asked Questions (FAQ)
What industry sector is represented by legacy SIC code 3621? ▾
Legacy SIC code 3621 represents 'Motors and Generators', categorized under Division Division D: Manufacturing and Major Group Major Group 36: Electronic and Other Electrical Equipment and Components. The Standard Industrial Classification (SIC) system was developed in the late 1930s.
What is the modern 2022 NAICS equivalent for legacy SIC 3621? ▾
Legacy SIC code 3621 maps to the modern 2022 NAICS industry classifications: NAICS 335312 (Motor and Generator Manufacturing). Mappings are resolved transitively across successive updates to handle splits.
Why do credit agencies and banks still reference legacy SIC code 3621? ▾
Registries like Dun & Bradstreet, insurance underwriters, and private platforms retain SIC code 3621 because their historical financial risk data and scoring models are indexed using the legacy 4-digit SIC framework.
Does the SEC EDGAR system allow searching public filings by SIC 3621? ▾
Yes. The SEC Division of Corporation Finance assigns a primary 4-digit SIC code to public companies. You can search the EDGAR database using SIC code 3621 to group reporting peer firms.
How do OSHA safety recordkeeping rules apply to SIC code 3621? ▾
Under 29 CFR Part 1904 safety regulations, OSHA references legacy SIC codes including 3621 to determine if a physical establishment is required to maintain daily injury logs (Form 300) or is partially exempt.
What is the structural difference between SIC 3621 and NAICS codes? ▾
SIC code 3621 classifies establishments based on their final product output or market destination (what they sell), while modern NAICS codes classify them based on production processes and inputs (how they work).
What are the typical business activities classified under legacy SIC 3621? ▾
Typical business activities classified under legacy SIC 3621 are the operations associated with 'Motors and Generators'. Mapped modern NAICS codes can be referenced for specific current examples.
Is legacy SIC code 3621 uniform across all 50 U.S. states? ▾
Yes, the Standard Industrial Classification (SIC) system, including code 3621, was published as a federal standard and remains uniform nationwide. It is still referenced by various state workers' compensation boards and departments of labor.
Sources & References
- U.S. Department of Labor (OSHA): OSHA Standard Industrial Classification (SIC) Manual — Code 3621
- U.S. Census Bureau: 1987 SIC to 2022 NAICS Concordance Tables
- Federal Reserve Board: Industrial Production & Capacity Utilization Classifications
- Internal Revenue Service (IRS): Schedule C Principal Business Activity (PBA) Industry Concordance
- Office of Management and Budget (OMB): Standard Industrial Classification Systems Governance