SIC Code 3677 — Electronic Coils, Transformers, and Other Inductors

4-digit industry in the 1987 Standard Industrial Classification — still requested by banks, insurers, SEC filings and legacy systems.

Code	3677
Title	Electronic Coils, Transformers, and Other Inductors
System	SIC 1987 (final edition — replaced by NAICS in 1997)

The SIC was last revised in 1987 and officially superseded by NAICS in 1997, but it never fully disappeared: the SEC still tags EDGAR filings with SIC codes, and many banks, insurers and legacy databases keep requesting it. That is why converting between the two systems is still routine work.

NAICS equivalents of SIC 3677

From the official U.S. Census concordance (1987 SIC → 2002 NAICS). Where the 2002 code no longer exists in NAICS 2022, the closest current code is shown.

NAICS 2002	Title (2002)	Current 2022 code
334416	Electronic Coil, Transformer, and Other Inductor Manufacturing	334416 (same code)

Other SIC codes in 36xx

• 3612 — Power, Distribution, and Specialty Transformers
• 3613 — Switchgear and Switchboard Apparatus
• 3621 — Motors and Generators
• 3624 — Carbon and Graphite Products
• 3625 — Relays and Industrial Controls
• 3629 — Electrical Industrial Apparatus, Not Elsewhere Classified
• 3631 — Household Cooking Equipment
• 3632 — Household Refrigerators and Home and Farm Freezers
• 3633 — Household Laundry Equipment
• 3634 — Electric Housewares and Fans
• 3635 — Household Vacuum Cleaners
• 3639 — Household Appliances, Not Elsewhere Classified

Data: 1987 SIC titles (OSHA/Census) and official Census concordance — U.S. government works in the public domain (17 U.S.C. §105). Suggested reference, not an official determination.