HS Code for Industrial Transformer: 8504.31 vs 8504.32 vs 8504.34 by Power
Industrial power transformers classify into HTS 8504 by power capacity. 8504.31 covers liquid-dielectric over 650 kVA. 8504.34 covers dry-type 16 to 500 kVA. Distribution transformers, traction transformers, instrument transformers each have their own subheading.
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Open calculatorHS Code for Industrial Transformer: 8504.31 vs 8504.32 vs 8504.34 by Power
US grid investment in 2026 has put transformer imports under unprecedented duty pressure. Distribution transformers, pad-mount transformers, dry-type transformers for indoor switchgear, and large substation transformers all classify into HTS 8504 sub-headings split by liquid-vs-dry and by power capacity. Misclassifying between subheadings does not change the Section 301 status (all in 8504 are on List 1) but it does change the MFN, the Section 232 derivative scope on the steel tank, and the USMCA qualification feasibility.
This guide covers the heading structure, the active duty stack by origin, the Section 232 derivative posture on tanks, and worked examples for typical grid procurement lanes.
Heading 8504 transformer subheadings
| Subheading | Description |
|---|---|
| 8504.21 | Liquid-dielectric, output not exceeding 650 kVA |
| 8504.22 | Liquid-dielectric, exceeding 650 kVA but not 10,000 kVA |
| 8504.23 | Liquid-dielectric, exceeding 10,000 kVA |
| 8504.31 | Other transformers (dry-type), output not exceeding 1 kVA |
| 8504.32 | Other transformers (dry-type), exceeding 1 kVA but not 16 kVA |
| 8504.33 | Other transformers (dry-type), exceeding 16 kVA but not 500 kVA |
| 8504.34 | Other transformers (dry-type), exceeding 500 kVA |
| 8504.40 | Static converters (rectifiers, inverters, UPS) |
| 8504.50 | Other inductors |
| 8504.90 | Parts |
For US grid distribution work, the most common imports are 8504.22 (medium pad-mount), 8504.33 (dry-type medium), and 8504.34 (dry-type large).
Active 8504 transformer AD/CVD orders
Active orders relevant to transformer imports as of 2026:
- A-580-867 (large power transformers from Korea): producer-specific rates 0 to 60 percent.
- A-549-840 (large power transformers from Thailand): under review.
- AD/CVD on amorphous metal cores (used in some transformer cores): A-570-998.
- No active orders on Mexican or Canadian transformer imports.
Worked example: Chinese 1 MVA dry-type transformer
200,000 USD per unit, HTS 8504.34, Chinese origin.
| Charge | Rate | Base | Amount (USD) |
|---|---|---|---|
| MFN duty | 1.7 percent | 200,000 | 3,400 |
| Section 301 List 1 | 25 percent | 200,000 | 50,000 |
| Section 122 | 10 percent | 200,000 | 20,000 |
| Section 232 derivative (steel tank 40 percent of value) | 50 percent | 80,000 | 40,000 |
| MPF | 0.3464 percent | 200,000 | 614.35 (capped) |
| Total | 114,014.35 |
Effective rate 64.0 percent. Chinese transformer landed cost is roughly 1.7x the FOB price. Most US utilities have moved sourcing to Korean, Mexican, or US-built supply.
Worked example: Korean large power transformer
500,000 USD HTS 8504.23 large substation transformer from Hyundai Electric Korea. Producer-specific AD rate 0 percent.
| Charge | Rate | Base | Amount (USD) |
|---|---|---|---|
| MFN duty | 0 percent (KORUS) | 500,000 | 0 |
| Section 122 (KORUS does not exempt) | 10 percent | 500,000 | 50,000 |
| AD (Hyundai 0 percent specific) | 0 | 0 | 0 |
| Section 232 derivative (steel tank ~35 percent of value) | 50 percent | 175,000 | 87,500 |
| MPF | capped | 500,000 | 614.35 |
| Total | 138,114.35 |
Effective rate 27.6 percent. The Section 232 derivative on the steel tank and the Section 122 surcharge stack additively (KORUS does NOT carve out Section 122). Korean transformers under KORUS plus 0 percent producer AD remain the most cost-effective import path for large substation procurement among non-USMCA origins, but the Section 122 layer is now the largest single duty after the 232 derivative.
Worked example: Mexican-built distribution transformer
100,000 USD HTS 8504.22 pad-mount transformer from Prolec Mexico. US silicon steel core, Mexican manufacturing.
| Charge | Rate | Base | Amount (USD) |
|---|---|---|---|
| MFN duty | 0 percent (USMCA qualifying) | 100,000 | 0 |
| Section 122 (USMCA exempt) | 0 percent | 0 | 0 |
| Section 232 derivative (US-melt steel tank within TRQ) | 0 (US-melt or USMCA-qualifying) | 0 | 0 |
| MPF | 0.3464 percent | 100,000 | 346.40 |
| Total | 346.40 |
Effective rate 0.35 percent. USMCA-qualifying Mexican transformers with US-melt steel are essentially duty-free. The major US utility sourcing pivot from 2022 onward has been from Asian to Mexican production for this exact arithmetic reason.
Worked example: ABB Canadian-built dry-type
150,000 USD HTS 8504.34 dry-type from ABB Canada.
| Charge | Rate | Base | Amount (USD) |
|---|---|---|---|
| MFN duty | 0 percent (USMCA qualifying) | 150,000 | 0 |
| Section 122 (USMCA exempt) | 0 percent | 0 | 0 |
| Section 232 derivative (Canadian-melt steel within TRQ) | 0 | 0 | 0 |
| MPF | 0.3464 percent | 150,000 | 519.60 |
| Total | 519.60 |
Effective rate 0.35 percent. ABB Canada (Varennes, Quebec facility) has been a beneficiary of the US grid procurement re-shoring.
Section 232 derivative on the tank
Distribution and pad-mount transformers have a sheet-steel tank as the largest single steel component. The 2025 Section 232 derivative annex expansion includes specific 8504.22 and 8504.34 subheadings where the steel content of the tank is significant.
The derivative rule applies at 50 percent on the steel-value portion only with producer affidavit. The affidavit identifies the tank steel value share, the smelt or melt country, and the heat numbers.
Without the affidavit, the default-rule applies 50 percent to the full transformer value, which can multiply the duty by 2 to 3x for tank-heavy designs.
Documentation that supports the classification
- Manufacturer data sheet specifying liquid-vs-dry, kVA rating, voltage class.
- Wiring diagram identifying primary, secondary, taps.
- BOM with steel content by component.
- For Section 232 affidavit purposes, the silicon steel core supplier and origin.
Run your transformer entry now
The LandedFees calculator handles 8504 with country-specific stacking, the active AD producer rates for Korean and Thai large power transformers, the Section 232 derivative tank steel split, and the KORUS / USMCA preferences.
Section 122 status as of June 20 2026
The May 7 2026 Court of International Trade ruling in Oregon v. United States (consolidated with Burlap and Barrel v. United States) struck down the Section 122 proclamation. The Federal Circuit issued an administrative stay on May 12 2026, so CBP is still collecting the duty pending appeal. Importers paying now should preserve protest rights and refund claims in case the government loses on the merits. The underlying Section 122 authority sunsets July 24 2026 under the statutory 150-day ceiling, regardless of the appeal outcome, unless Congress extends or a fresh proclamation restarts the clock.
Citations
- USITC Harmonized Tariff Schedule heading 8504: https://hts.usitc.gov/?query=8504
- Commerce ADCVD on large power transformers Korea: https://access.trade.gov
- Section 232 derivative annex 2025 expansion
- USTR Section 301 List 1
- USMCA chapter 85 rule of origin
Frequently asked questions
Which subheading covers a 1 MVA dry-type transformer?
HTS 8504.34.0000 (other dry-type transformers, output exceeding 500 kVA but not exceeding 1600 kVA). The subheading splits dry vs liquid first, then by power band. Verify against the HTS at the time of import; statistical annotations change.
What is the difference between 8504.31 and 8504.32?
8504.31 covers liquid-dielectric transformers above 650 kVA (large power and substation transformers). 8504.32 covers liquid-dielectric below 650 kVA (distribution transformers on poles or in pads). 8504.33 covers liquid-dielectric of 650 to 10,000 kVA in some annotations; check current.
Are transformers on Section 232 derivative?
Yes for steel-rich transformer enclosures and tanks. Section 232 applies to the steel-content portion only with producer affidavit. For a typical pad-mount distribution transformer the steel content is 40 to 60 percent of value, so Section 232 derivative is the binding duty layer.
How does Section 301 apply to Chinese transformers?
HTS 8504.31 through 8504.34 are on Section 301 List 1 at 25 percent. Combined with Section 122 (10 percent) and Section 232 derivative on the steel tank, Chinese transformers stack at 60 to 90 percent total duty depending on size and steel share.
What does USMCA require for transformers?
Chapter 85 rule of origin. Tariff shift from outside 8504 plus 60 percent transaction value RVC if non-originating materials include items in 8504.90 (parts of transformers). Mexican and Canadian transformer producers using US silicon steel meet the rule readily.
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