Sourcing current transformers from China
Current transformers and the selected core and parts lines carry 0% UK duty from China. Confirm conformity requirements for the supplied component and finished assembly before sale, rather than assuming every unit needs a separate mark. Specify ratio, burden and insulation. Cambridge China Bridge sources current transformers.
UK duty on current transformers and parts
Heading 8504 covers electrical transformers, static converters and inductors. For current measuring transformers not exceeding 1 kVA, assess 8504 31 29 90 against the product specification. Separately imported cores and other transformer parts have their own lines; these parts codes also cover components for other transformers and inductors.
Read from the UK Trade Tariff on 7 October 2026, the selected lines carry 0% duty for goods from China. The supplied record lists no anti-dumping or countervailing duties, suspensions or attached import controls for these lines. Import VAT at 20% still applies.
Confirm the commodity code using the measuring function, power handling capacity, construction and shipment contents. See power supplies, transformers and inverters for the wider heading.
| Goods | Commodity code | Duty | Anti-dumping or countervailing duty on China |
|---|---|---|---|
| Current measuring transformers, not exceeding 1 kVA, other | 8504 31 29 90 | 0% | None |
| Ferrite cores for transformers and inductors | 8504 90 11 00 | 0% | None |
| Steel laminations for transformers and inductors | 8504 90 13 10 | 0% | None |
| Other parts of transformers and inductors | 8504 90 17 00 | 0% | None |
Specify ratio, burden and insulation
State whether the transformer is for metering or protection. Specify primary and secondary current, ratio accuracy, phase displacement, rated burden and frequency. Define the current range and connected burden over which performance must be demonstrated. For protection applications, agree saturation behaviour and the test method.
Choose split-core or solid-core construction and specify the aperture, mounting, lead length, terminal layout and polarity markings. State insulation expectations, operating conditions and compatibility with the intended meter or relay. Approve a drawing and a sample tested with that equipment.
Official conformity guidance says a single marking covering the overall product is sufficient for many products. Ask a testing specialist to confirm the applicable electrical safety and electromagnetic compatibility requirements for the supplied component and finished assembly before sale in Great Britain. Match any supporting reports to the exact model and construction.
Worked duty example
Illustrative example, not a quote: Illustrative order: 3,000 current transformers for meter assemblies under 8504 31 29 90, invoiced at £12,000 free on board, with £800 of freight and insurance to the UK. The customs value is £12,800. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £12,800, so it is £2,560. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.
Inspection checklist
Ratio and polarity: measure transformation ratio and verify terminal polarity against the approved drawing.
Accuracy and burden: check ratio error and phase displacement across the agreed operating range with the specified connected burden.
Construction and insulation: inspect winding protection, terminals, housing cracks and split-core mating faces; review the agreed insulation test results.
Arrival and identification: check aperture dimensions, mounting fit, labels, batch records and transport damage. Use quality inspection to agree acceptance checks before shipment.
What goes wrong
A transformer can produce the expected ratio in a simple sample test yet give inaccurate readings with the buyer's meter and cable burden. Reversed polarity can also produce misleading measurements. Test with the intended circuit and record the connections alongside the results.
Gaps or contamination at split-core mating faces, substituted core material and changed windings can alter performance despite an unchanged housing. Agree approval of material changes and compare production samples with the retained sample and test records.
Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For components and parts, see sourcing for manufacturers.
Frequently asked questions
What is the UK import duty on current transformers from China?
The supplied tariff record gives 0% for 8504 31 29 90 and the selected core and parts lines, with no anti-dumping or countervailing duty. Import VAT at 20% still applies.
What commodity code covers current transformers?
For current measuring transformers not exceeding 1 kVA, assess 8504 31 29 90. Confirm the measuring function and specification; separately imported cores and parts use different lines.
Does every current transformer need a separate CE mark?
Official guidance says a single marking covering the overall product is sufficient for many products. Have a specialist confirm the position for your supplied component and finished assembly.
How do I check a current transformer's accuracy?
Agree the current range, burden and test method. Measure ratio error and phase displacement with the intended meter or relay, and verify polarity against the drawing.