The short answer
A Calgary business considering 400A needs a documented load and service assessment, including voltage, phase, metering and upstream utility capacity. A 400A panelboard specification alone does not establish an approved 400A service.
01 / Project knowledge
Begin with the business demand
Document the existing equipment and the proposed expansion: motors, HVAC, process equipment, cooking, refrigeration, EV charging and other fixed loads as applicable. Ask the qualified designer to state operating assumptions and the demand calculation used for the proposed supply.
A smaller panel change, additional distribution or management of selected loads may be suitable for some projects. A larger service may be justified for others. The decision should follow the assessment rather than a preselected amp target.
02 / Project knowledge
Review the entire service path
The panel, feeder, main disconnect, meter and utility connection can have different limiting conditions. Confirm the approved arrangement and which parts need alteration. Identify available fault-current and equipment-rating considerations through the qualified project team.
For ENMAX-served commercial service modifications, prepare the utility’s requested service details, site plan and single-line diagram. Keep the feasibility response with the contractor’s proposed scope before ordering service equipment.
03 / Project knowledge
Separate installation from utility and civil work
A service change can affect metering, service entrance, cable route or underground infrastructure. Ask who owns each part and whether trenching, surface reinstatement, utility charges or additional design are included. These are address-specific questions, not automatic features of every 400A job.
04 / Project knowledge
Plan the business interruption
Define the shutdown window and tenant or production impacts. Confirm the permit, inspection and utility reconnection requirements with the responsible parties. If temporary supply is needed, it requires a designed scope rather than an informal workaround.
- Accepted equipment and demand information.
- Proposed amps, voltage and phase.
- Utility response and drawing requirements.
- Itemized installation and excluded infrastructure work.
- Outage, inspection, reconnection and restart plan.
Questions we hear
Is 400A the correct size for every small commercial building?
No. Building use, equipment, demand and supply arrangement vary. A qualified assessment should establish the proposed rating.
Can a 400A panel be quoted without confirming the utility?
A distribution-only quote and a service increase must be distinguished. Obtain utility feasibility where the incoming supply changes.