How Is Electrical Service Sized for a Modern Warehouse?

I assemble the connected load from every system in the building: conveyor and sortation motors with their VFD profiles, hydraulic leveler power units, the forklift charger bank with coincident peak at shift change, dock door operators, high-bay lighting by zone, rooftop HVAC units, office and break-room loads, exterior and site lighting, and the IT room with UPS losses. NEC demand and diversity factors apply where the code permits — lighting, receptacles, and HVAC each have their own rules — but I stay conservative on loads that genuinely coincide, like a full charger bank. The load letter that goes to the utility is this list with the math shown, because the utility sizes its transformer from it.

Every warehouse grows electrically: the tenant adds a sort line, doubles the charger bank, or electrifies the yard fleet. I design for that growth with spare breaker space in the switchboard, oversized main bus where the budget allows, and spare conduits stubbed from the electrical room toward the dock wall, the charger area, and the parking field — labeled, capped, and on the as-builts. Submetering provisions let a future subdivided tenant get its own bill without a retrofit. The goal is a building where the next three electrical projects are breaker-and-conduit jobs, never a service replacement.

A warehouse electrical service design is ready when it clears this checklist. Services fail when day-one math meets year-three reality — these items close that gap. • Connected-load inventory with NEC demand factors, including coincident charger peaks • 480Y/277V distribution for floor loads with 208Y/120V step-down for office and receptacles • 20 to 25 percent spare capacity plus physical breaker space and labeled spare conduits • EV fleet charging reserved: switchboard space, pathways, and utility coordination • Solar-ready pathways, backfeed-rated service, and early utility interconnection talks