Distribution boxes can be broadly categorized by their voltage level, application environment, and primary function. The two most fundamental distinctions are between Low-Voltage Distribution Boards and Medium-Voltage Distribution Enclosures, often referred to as Ring Main Units. What do the primary, secondary, and tertiary boxes of a distribution box mean? This is a relative issue. Let's make a hypothesis: a newly built residential area introduces a 10kV incoming line and builds a distribution room. The outgoing line from the low-voltage end of the transformer is 0. We'll chat about what each one does, where it shines, and then dive into how to choose the perfect box for your needs. Plus, we'll sprinkle in some practical tips to make sure you're not. (1) Fixed panel switchgear, often called switchboard or distribution panel. Industrial distribution boxes are.