An assembly classifies under 8537 when it incorporates two or more apparatus for switching, protecting, or connecting electrical circuits — mounted together on a common base or in a common enclosure — and functions as a coordinated control or distribution unit. A single switch or breaker in a housing remains in its own heading; the combination into a panel or board triggers classification here under GRI 1 and the heading text.

No — a single article is classified as a whole. The voltage rating of the panel's primary or highest-rated section, as specified by the manufacturer, typically determines whether it falls under 853710 (not exceeding 1,000 V) or 853720 (exceeding 1,000 V). For panels with ambiguous ratings, a binding ruling from CBP is the appropriate path.