The Harmonized System (HS), maintained by the World Customs Organization, classifies traded goods with six-digit codes that are shared worldwide. Countries add further digits for their national tariffs.
## Heading 8504
Electrical transformers fall under heading 8504. At the six-digit level, liquid-dielectric (oil-immersed) transformers are split by power handling capacity:
- 8504.21 — not exceeding 650 kVA
- 8504.22 — exceeding 650 kVA but not exceeding 10,000 kVA
- 8504.23 — exceeding 10,000 kVA
Other (for example dry-type) transformers fall under 8504.31 to 8504.34 by capacity, and parts under 8504.90.
## Why the national code matters
National tariff lines (8 or 10 digits) differ between countries, as do duty rates, certifications and import rules. Classification of assemblies such as package substations, or of parts such as tanks and radiators, depends on the exact goods and local rulings. Always confirm the final code with the destination customs authority or a licensed customs broker.
Use the HS search in our export resources as a starting point, not as a binding ruling.
General trade information, not legal or customs advice.