What Is a Three-Phase Service Upgrade?
A three-phase service upgrade brings three-phase supply into a facility, or increases the capacity of an existing three-phase service, along with the switchgear and distribution to use it. In the Toronto area that means either 120/208V, which suits commercial equipment and smaller motors while providing standard 120V circuits directly, or 347/600V, which suits larger motor loads and long distribution runs with step-down transformers where lower voltage is needed. Both configurations are sized and terminated to the Ontario Electrical Safety Code (OESC).
The reason to move to three-phase is motor load. A three-phase motor draws balanced current across three conductors, starts more smoothly, and runs more efficiently than a comparable single-phase motor. For a facility running compressors, pumps, machine tools, conveyors or commercial refrigeration, three-phase is not a preference, it is what the equipment is built for.
Two things decide whether the project is straightforward or long. First, whether three-phase supply exists at your address, which varies street by street and is the first thing we confirm with the utility. Second, the utility’s own infrastructure work, because a transformer or primary extension has its own cost and timeline entirely outside the contractor scope.
For the industrial range, see industrial electrical panel upgrades.
Configuration Options
- Three-phase distribution, supply already available. The existing service is three-phase and the work is switchgear and distribution capacity.
- New three-phase service with switchgear. Converting a single-phase property where the utility can supply three-phase.
- 347/600V service with transformer coordination. Higher voltage distribution with step-down transformers for 120/208V loads. See 600V electrical service upgrades.
- Three-phase with motor control centres. Distribution plus the starters and controls the machinery needs.
When a Facility Needs Three-Phase
- Three-phase equipment is being installed. Machine tools, compressors, larger HVAC and commercial refrigeration are usually specified for it.
- Single-phase motors are tripping or running hot. A sign the load has outgrown the supply arrangement.
- Distribution runs are long. Higher voltage and balanced current reduce conductor size and voltage drop across a large building.
- A production line is expanding. Simultaneous motor starts change the demand profile, not just the total load. See manufacturing facility electrical upgrades.
- Forklift or fleet charging is being added. Several chargers is a capacity and a distribution question. See warehouse electrical upgrades.
What Drives the Cost Between $5,000 and $15,000
Whether the supply already exists is the biggest factor in the contractor scope. Voltage class is second: 347/600V equipment and the step-down transformers that accompany it cost more than 120/208V. Switchgear size and section count is third, driven by how many feeders the facility needs. Cutover constraints are fourth, because a shutdown window or temporary supply both add cost.
Separate from all of this is the utility’s own work. A new transformer, a vault or a primary extension is priced by the utility and is frequently the largest single number in a three-phase project. We tell you that early rather than letting it appear late.
What to Expect Through the Project
The first phase is investigation and paperwork: the load study covering running currents, starting currents and duty cycles, the utility service application, and the commercial ESA plan review with the single-line diagram, equipment ratings and short-circuit current rating verification.
Installation normally happens alongside the existing system so the cutover is short. Switchgear is set, feeders are run to distribution panels and motor control, and terminations are torqued to specification. Before any motor is energized, phase rotation is verified and documented, because reversed rotation damages equipment on the first start.
The cutover runs in the agreed window, the ESA inspector attends, and the utility energizes. You receive the final single-line diagram, switchgear and panel schedules, the rotation and voltage verification records, the Certificate of Inspection and the itemised invoice.
