How to Plan a Commercial Electrical Upgrade With Minimal Downtime

For most businesses the electrical work isn't the expensive part of an upgrade — the closed hours are. A panel swap that takes a day can cost a restaurant a weekend of covers if it lands wrong. The good news is that downtime is largely a planning problem, and most of it can be designed out before anyone picks up a tool.

Start with what you actually draw

Before scoping anything, we want real numbers: existing service size, measured demand, and the loads you plan to add over the next few years. Metered readings over a week beat nameplate math every time, because nameplate totals almost always overstate reality.

That study decides whether you need a full service upgrade, a subpanel, or simply rebalanced circuits. It's common for a business expecting a new service to only need distribution work — a much shorter and cheaper outage.

The utility lead time drives the calendar

If the upgrade touches the service entrance, meter, or transformer, APS sets the schedule, not your contractor. Applications, engineering, and equipment can run weeks to months, especially for three-phase service or a larger transformer. Submit early. Everything else can be sequenced around it.

Phase the work so the building keeps running

Most upgrades can be broken into stages where each stage ends with the building fully operational. Typical approach:

• Install new conduit, feeders, and panels in parallel with existing gear energized.
• Move circuits over in small groups, area by area, during low-volume hours.
• Reserve one short, planned outage for the actual service cutover.
• Decommission old equipment afterward, with no impact on operations.

Temporary feeds or a rental generator can cover critical systems — walk-in coolers, servers, security — through the cutover window.

Plan the outage window like an event

The cutover deserves a written sequence: start time, who's on site, what gets shut down in what order, what has to be back up first, and who confirms each system afterward. Tell staff in advance, back up anything that lives on a local machine, and know which equipment needs a controlled shutdown rather than a hard power loss.

Build inspection into the schedule

Permits and inspection aren't optional on commercial work, and an inspection that can't happen until Tuesday can hold a Saturday cutover energized on temporary power. We coordinate inspection timing as part of the schedule so the sequence doesn't stall waiting on a sign-off.