Sourcing moulded circuit-breaker cases from China

Zero duty for cases classified under heading 8538

Heading 8538 covers parts suitable solely or principally for the apparatus of headings 8535, 8536 or 8537. This guide concerns empty moulded circuit-breaker cases and covers supplied for assembly. The table shows product variants against the same general parts line, rather than separate tariff classifications.

Read from the UK Trade Tariff on 1 October 2026, all supplied heading 8538 lines carried 0% duty for goods from China. The general parts line 8538 90 99 99 had no listed anti-dumping or countervailing duty, suspension or import control. Import VAT is separate from customs duty.

Ask your broker to confirm the commodity code using the drawing, material composition, insulating function and intended breaker model. Treat the table code as conditional until that review is complete. For related parts within the wider heading, see circuit-breaker arc chutes.

Specify the resin and breaker interfaces

Name the resin manufacturer and grade, filler, colour, permitted recycled content and moulding process. Specify wall thickness, mounting bosses, threaded inserts, terminal openings, mechanism seats, arc-chute pockets and the mating surfaces between base and cover. Agree drawing tolerances, material substitution approval and mould-cavity identification.

Ask the breaker designer to set heat resistance, flame behaviour, insulation and mechanical test criteria for the intended assembly. Obtain reports matching the resin grade and moulded design. The finished breaker must comply with applicable legislation when placed on the Great Britain market. Agree the evidence needed with the assembler through testing and certification.

Worked duty example

Illustrative example, not a quote: 5,000 moulded circuit-breaker case sets, assuming classification under this code; illustrative only under 8538 90 99 99, invoiced at £12,000 free on board, with £600 of freight and insurance to the UK. The customs value is £12,600. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £12,600, so it is £2,520. 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

Material: match resin batch records and material certificates to the agreed grade, filler and colour; investigate any unapproved substitution.

Moulding: inspect for cracks, voids, short shots, flash, exposed filler and distortion, especially around thin partitions, inserts and screw bosses.

Fit: measure the agreed critical dimensions and trial-assemble bases and covers with the intended mechanism, terminals and arc chutes; check handle movement and insert retention.

Arrival: check cavity and batch identification, matched case sets and packing damage. Keep damaged parts separate and compare retained samples during quality inspection.

What goes wrong

A substituted resin can change heat performance, shrinkage and brittleness. Warped mating surfaces leave gaps, flash obstructs mechanism movement, and weak bosses crack during tightening. Inserts that move during moulding can prevent the terminals or mechanism from seating correctly.

An exterior that matches the approved sample can conceal incorrect internal geometry or material. Inspect critical interfaces from every mould cavity and trial-assemble production samples. A resin certificate and a visual inspection do not demonstrate the safety of the finished breaker.

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.