Sourcing NTC thermistors from China

NTC thermistors: 0% duty within heading 8533

Heading 8533 covers electrical resistors, including rheostats and potentiometers, but excludes heating resistors. This guide concerns NTC thermistors whose resistance falls as temperature rises. The table shows buying formats against the same candidate other-variable-resistor line, for power handling not exceeding 20 W; these are not separate tariff subdivisions or confirmed classifications for every thermistor.

Read from the UK Trade Tariff on 4 November 2026, every supplied line in heading 8533 carries 0% duty for goods from China. The supplied data lists no anti-dumping or countervailing duty, suspensions or attached import controls. Zero duty does not remove import VAT; see the import duty and VAT guide.

Confirm the commodity code using the UK Trade Tariff and the exact datasheet, power rating and supplied construction. Ask your customs broker to distinguish a standalone thermistor from a complete sensing assembly. For other resistor families, see resistors and potentiometers.

Specify the temperature curve and construction

State nominal resistance at the agreed reference temperature, resistance tolerance, the resistance-versus-temperature table and its tolerance, and the beta parameter with its temperature interval. Specify operating temperature range, response time, dissipation behaviour and permissible measurement current. For inrush-limiting discs, also agree cold resistance, continuous current and the intended circuit conditions.

For probes, agree sheath material, sealing, cable insulation, connector, lead length and mounting position. Obtain material declarations and supporting reports for the exact part number so an in-scope finished electrical product can meet hazardous-substance restrictions. Supplier confirmation does not replace the finished-product manufacturer's compliance assessment.

Worked duty example

Illustrative example, not a quote: 10,000 glass-encapsulated NTC thermistors, illustrative only, assuming this classification is confirmed under 8533 40 10 00, invoiced at £9,000 free on board, with £300 of freight and insurance to the UK. The customs value is £9,300. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £9,300, so it is £1,860. 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

Resistance curve: measure samples at the agreed temperatures after stabilisation, using the agreed low measurement current to limit self-heating.

Construction: compare body dimensions, coating, lead spacing, probe sealing and connector wiring with the approved drawing and sample.

Application behaviour: check response time in the intended mounting arrangement; for inrush discs, test under the agreed circuit conditions.

Traceability: match packaging, manufacturer, part number and batch identifiers to the order, material declarations and test records. Retain samples from each received batch.

What goes wrong

Parts can match nominal resistance yet have a different temperature curve, causing incorrect readings away from the reference temperature. Measurement current can heat the thermistor and distort inspection results. A changed coating, sheath or mounting arrangement can also alter response time.

Probe orders can fail through moisture ingress, weak cable joints or substituted insulation. Inrush discs can fail when selected by cold resistance alone. Agree acceptance methods before production and compare bulk samples with the approved part. Use the quality inspection guide to document checks and rejected batches.

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.