Power supplies, transformers and inverters from China

0% duty on heading 8504

Read from the UK Trade Tariff on 29 September 2026, every line of heading 8504 in the table below carried 0% on goods from China, with no anti-dumping duty. That covers small and large transformers, AC-DC power supplies and adapters, battery chargers, rectifiers, inverters, inductors and parts of converters.

Because the duty is zero, classification mistakes here cost little in duty but can still delay clearance. Most plug-in adapters and open-frame power supplies are other static converters under 8504 40 95; battery chargers are 8504 40 60, and solar inverters with maximum power point tracking 8504 40 84. Confirm the commodity code from the specification, and check VAT separately: import VAT at 20% still applies.

Safety and EMC

A power supply, charger or transformer with a mains input between 50 and 1,000 V AC is electrical equipment under the Electrical Equipment (Safety) Regulations 2016, and almost all of them also fall under the Electromagnetic Compatibility Regulations 2016. Each needs technical documentation, a declaration of conformity and UKCA or CE marking, and the importer's name and address on the product or its packaging.

Ask for the safety test report against the product standard the factory designed to, the EMC test report, and the declaration of conformity for the exact model and rating. Check that the report names the same model, the same factory and the same transformer and circuit board as the sample; a report for an earlier version is the most common mismatch. Our CE and UKCA guide covers the documents in general.

Efficiency rules for external power supplies and transformers

An external power supply up to 250 W, sold for household and office equipment, must meet Regulation (EU) 2019/1782 as it applies in Great Britain. Annex II caps no-load power at 0.10 W for an ordinary AC-DC supply up to 49 W and 0.21 W above that, sets a minimum average active efficiency (0.88 for an AC-DC supply over 49 W), and requires output power, voltage and current on the nameplate. The Regulation does not apply to battery chargers without a power supply function, lighting converters, uninterruptible power supplies or supplies for medical devices.

Power transformers of 1 kVA or more used in 50 Hz transmission and distribution networks or in industrial applications fall under Regulation (EU) No 548/2014 as it applies in Great Britain, which sets minimum efficiency by rating. Ask the maker to state the load and no-load losses and the tier the transformer meets, and check them on the routine test report.

What to test before you pay

For power supplies and chargers, test samples from the bulk under full load for several hours: output voltage and ripple, temperature of the case and transformer, no-load power, efficiency, and short-circuit and over-voltage protection. Weigh one against the approved sample and open it: lighter units often have a smaller transformer, fewer capacitors or missing filtering, which is where cheap supplies fail.

For transformers, ask for the routine test report for each unit (ratio, winding resistance, losses and insulation tests), and witness the tests on large units. Quality inspection sets out the stages, and our testing and certification service can arrange independent testing.

Worked duty example

Illustrative example, not a quote: 3,000 own-brand 65 W USB-C chargers under 8504 40 95 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 nil. Import VAT at 20% is £2,560, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Related guides and how we help

For related products see electrical cable and wire harnesses, EV chargers, renewable energy products and electronics.

Cambridge China Bridge checks power supply and transformer makers in China, matches the test reports to the product, and inspects the goods before shipment; see factory verification.

For UK manufacturers buying machinery or components to drawing, see our service for manufacturers, or send a procurement brief.