What is the primary feed for a 480v to 208v 100amp panel 3phase?

The primary feed for a 480V to 208V, 100 amp panel in a three-phase system typically consists of three phases (L1, L2, L3) and a neutral wire, coming from a step-down transformer designed to convert the higher voltage to the lower voltage. The transformer will have a primary side connected to the 480V supply and a secondary side that outputs 208V. Additionally, proper grounding must be ensured for safety and compliance with electrical codes. The panel will distribute the 208V power to various circuits as needed.