Classification follows the primary energy source. In a diesel-electric locomotive, the diesel engine generates the electricity that powers the traction motors; the electric drive is a transmission mechanism, not an independent power source. Heading 8601 is reserved for locomotives that draw power from an external electrical supply or from onboard storage batteries as their primary motive source.

Locomotive tenders are explicitly included in heading 8602 under subheading 860290. If a tender is imported separately from its locomotive, it still falls here. Parts of locomotives, however, are classified under heading 8607 rather than 8602.