Equipment inside usually includes isolating switches, circuit breakers, and residual current devices (RCDs). Supplies power to specific buildings or floors. Let's make a hypothesis: a newly built residential area introduces a 10kV incoming line and builds a distribution room. Equipped with larger three-phase circuit. Primary power distribution: temporary electricity is in a place where the construction needs electricity, that is, from the transformer into the three-phase power supply, ground wire, neutral line. Tertiary Distribution Box: The final connection box for each electrical appliance, which can be movable or fixed. The complete set of products can form a complete three-level protection system for construction power, so as to. Box Size: Making sure the size of the box is adequate for both current requirements and potential future expansions.