How to Choose the Right Size and Capacity for a Lighting Distribution Box?

Selecting an incorrectly sized distribution box can lead to costly upgrades or safety risks. The right choice depends on a careful calculation of current and future electrical loads.

The process starts by calculating the total connected load of all lighting fixtures and any auxiliary devices (like lighting controllers) on the circuit. Apply demand factors as per electrical codes, which account for the fact that not all lights will be at full load simultaneously. This gives you the estimated maximum current demand.

Choose a distribution box with a main switch rating higher than this calculated demand. The number of ways (breaker slots) must accommodate all individual lighting circuits with spare capacity—typically 20% extra ways for future expansion. Consider the physical size: ensure there is enough space for all wiring and breakers without overcrowding, which violates code and creates a fire hazard. Consulting with a qualified electrical engineer during the planning phase is highly recommended to ensure the panel is correctly specified for the application's lifespan.