Resistance-heated furnaces generate heat by passing current through a fixed resistive element (such as a wire coil or silicon carbide rod), and the workpiece is heated by conduction, convection, or radiation from that element. Induction furnaces (851420) generate heat directly within the workpiece or a susceptor by inducing eddy currents through an alternating electromagnetic field. The heating mechanism — external resistive element versus electromagnetic induction — is the key classification criterion.

Standard resistance-heated industrial and laboratory furnaces do not require mandatory admissibility review by a US regulatory agency at entry. However, equipment incorporating radiation-producing components or lasers may require FDA Center for Devices and Radiological Health notification. Importers should also verify compliance with applicable OSHA and NFPA standards for end-use installation, though these are domestic requirements rather than import conditions.