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SITCSection 7
U.S. imports of insulating fittings for electrical machines — other materials (nes) (SITC 77329) totaled $22.1M in July 2026, traded with 38 countries.
Importers of Insulating Fittings for Electrical Machines — Other Materials (NES) paid $4.4M in duties in July 2026 — an effective duty rate of 28% on $16.0M in dutiable value, based on actual customs collections rather than the published tariff schedule. Insulating Fittings for Electrical Machines — Other Materials (NES) imports of $22.1M in July 2026 ran 19% above the year-to-date monthly average of $18.6M.
Basic heading 336 of 642 in section 7
Basic heading 77329 · $22.1M of $175.6B
Residual insulating fittings made from materials other than ceramics or plastics — including mica composites, vulcanized fiber, epoxy-glass laminates (such as FR4 or G10), and similar engineered dielectrics — serve specialized roles in high-temperature motor windings, transformer coil supports, and precision switchgear where neither standard ceramics nor commodity plastics meet the thermal or mechanical requirements. The 'not elsewhere specified' scope of this heading means correct classification requires ruling out the ceramic (77326) and plastic (77328) headings first. Epoxy-glass laminates in particular are a widely traded subcategory used extensively in printed circuit board and power electronics manufacturing.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
1.8K shipments/mo
Common materials include mica-based composites (micanite, mica paper laminates), vulcanized fiber, epoxy-glass laminates (FR4, G10, G11), and fish paper. These materials are chosen for applications requiring high dielectric strength at elevated temperatures — such as slot liners in electric motors, coil end-turn supports in transformers, or arc barriers in switchgear — where plastics would soften and ceramics would be too brittle or heavy.
Importers should retain material composition certificates or technical datasheets confirming that the fitting's primary insulating material is neither ceramic nor plastic. For epoxy-glass laminates, a laminate grade designation (e.g., NEMA FR4, G10) and resin content specification serve this purpose. For mica composites, the mica content percentage and binder type should be documented. CBP may request this documentation during a tariff classification review.
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Imports · July 2026
origin
Mexico and China together supply 41% of it.
customs district
Census does not publish district detail for this classification system.
destination
Census does not publish state detail for this classification system.
entry
Census does not publish port detail for this classification system.
ImportsExports
Imports
$22.1MYoY · Pro
Exports
$18.1MYoY · Pro
12-mo low · imports
YoY · ProThrough July 2026. Source: U.S. Census Bureau.