Service upgrades and load calculations

A load calculation tells you whether your building's electrical service can carry what you want to add: EV chargers, heat pumps, a kitchen, a production line or a new tenant. When the answer is no, a service upgrade increases the capacity of the connection to the utility. We do both, and we look hard at the options in between, because the cheapest kilowatt is often the one you can free up without replacing the service.

Many buildings are being asked to carry loads they were never designed for. Electrification of heating, EV charging and more equipment per tenant all add demand. A service upgrade can be one of the largest and slowest electrical projects a building takes on, with utility lead times, equipment lead times and planned outages. Knowing early whether you need one, and how big it must be, saves months.

What we look at

• The rating of the existing service: main switch or breaker, switchboard, service conductors and the utility transformer.
• Measured demand from utility bills or interval data, which shows how the building actually behaves.
• Calculated demand using the methods in the electrical code, with the demand factors that apply to each type of load.
• The new loads, their nameplate ratings and how and when they will run.
• The distribution downstream of the service: feeders, panels and transformers that may also be full.
• Options that reduce or shift demand: load management, scheduling, efficiency upgrades and power factor correction.
• The utility's requirements, lead times and available service sizes.

Measured demand, new loads and the service limit

For an existing building, the starting point is what the service actually carries at its busiest. The electrical code allows measured maximum demand over a full year to be used in some cases instead of a calculated figure, which often shows more spare capacity than a calculation from scratch would. New loads are then added using the code's rules for each type of equipment. If the total goes over the service rating, you have three choices: reduce or manage the new load, free up existing load, or upgrade the service.

How it works

1. Brief. We start by asking why: a specific new load, a building conversion, a heating electrification plan or repeated trips of the main breaker. We list the loads you plan to add now and in the next several years.
2. Data and site survey. We collect twelve months of demand data and survey the service, switchboard and key panels, reading nameplates and checking the condition of the equipment.
3. Load calculation. We calculate the total demand with the new loads, using measured data where the code allows it, and identify any feeders or panels that are also limiting.
4. Options. We compare load management, efficiency measures and a service upgrade, with the electrical work each one involves and how long each would take.
5. Upgrade design. If an upgrade is the answer, we size the new service, work with the utility on the connection, and prepare drawings and specifications. Drawings for permit are sealed by a licensed professional engineer where required.
6. Construction. Installation is done by licensed electrical contractors under permit. We plan the changeover and outage with you, review the work and update the drawings.

What to have ready

• Twelve months of utility bills, and interval data if your utility provides it.
• The single-line diagram and panel schedules, even if out of date.
• Nameplate data or specifications for the equipment you plan to add.
• Any history of main breaker trips, flickering or overheating.
• Your plans for the next several years, so the upgrade is sized once.

What you get

A load calculation you can show to the utility, the authority having jurisdiction and your contractor, with the method and assumptions written down. A clear statement of how much capacity is left and where the bottlenecks are. A comparison of options with the work each one needs. Where an upgrade is chosen, a design package ready for permit and tender, and a changeover plan that keeps outages short and scheduled.

A typical case

A mid-rise rental building wants to replace gas rooftop units with heat pumps and add chargers in the parkade. The calculation shows the existing service can take the heat pumps alone, but not both. Load management on the chargers, which mostly charge overnight when heating demand is lower but not absent, closes much of the gap. The remaining shortfall, and the owner's plans to electrify domestic hot water later, make an upgrade the better long-term choice. Because the utility's lead time is long, the upgrade application goes in first, and the heat pumps proceed on the existing service while it is processed.

Who it's for

• Owners and managers planning electrification, EV charging or major new equipment.
• Condominium boards facing owner requests that add load.
• Tenants and landlords negotiating capacity for a new lease.
• Buildings with main breakers that trip or equipment that is near the end of its life.

For background, read electrical load calculations, when to upgrade your electrical service, demand charges and power factor and EV load management.

Common questions