400 amp panel

How a project becomes a 400 amp panel requirement

The ampere figure is what buyers type; the purchase is the enclosure, interior, main device and feeder arrangement that must survive that duty. Electrical Panel Sourcing does not calculate the service size. Your licensed designer decides whether the project is a 400 amp panel, a pair of feeders, or a meter-main combination. We turn that decision into factory questions.

Light commercial feeder and workshop additions

Electrical condition: confirm rated voltage and phase, usually 120/240 V single phase or 208Y/120 V, and whether the 400 A figure is the bus, the main breaker, or a meter socket. Environment is often an indoor mechanical room with surface mounting. Confirm enclosure NEMA type, feed direction, and whether the interior must accept the breaker series already on the truck.

Before the request goes out, settle indoor versus outdoor mounting and the NEMA designation. Outdoor and washdown positions need different gasketing; an IP code from a factory, if offered, is not a translation of that NEMA type. Grounding and bonding arrangement stays with your designer. We only ask whether an isolated neutral and a separate ground bar are part of the equipment line.

Multi-tenant or campus distribution

Electrical condition: three-phase supply is more common, and a 400 amp panel may sit downstream of switchgear rather than at the service. Ask for interrupting capacity in kA and SCCR on the exact assembly, not a family brochure number. Selective coordination with upstream breakers or fuses is an engineering trade-off; we will not declare that the panel “coordinates” with unnamed gear.

Environment may be a shared electrical closet with limited depth. Confirm enclosure height, hinge side and whether a meter-main combination is in scope. Fuse versus circuit breaker choices at the branch level remain yours; our RFQ only records the interior the factory is offering.

Outdoor equipment pads and irrigation or process skids

Electrical condition: voltage, phase and whether heaters or lighting loads share the interior. Environment is rain, dust or washdown. Confirm NEMA enclosure type, dead-front hardware and any required lockable cover. Do not assume a painted indoor box can be quoted as an outdoor rated load center by adding a drip hood in prose.

What remains the buyer’s decision: service size, conductor sizing, AHJ approval, and whether fuses or breakers protect downstream circuits. What the factory must answer: bus rating, main device, spaces, enclosure type, breaker family, quantity and delivery terms. Browse forms of sub panel, upgrade RFQ steps, or send the site condition with the 400 A figure attached to a device type.