Three-phase power for Calgary commercial and industrial buildings

CCT 01When a building needs three-phase

Three-phase supply becomes necessary when the equipment says so. Larger motors, air compressors, CNC machines, welders, rooftop HVAC units, commercial kitchen lines, elevators and DC fast chargers are commonly built for three-phase only, and for heavy loads three-phase delivers the same power on smaller conductors with smoother motor operation. The trigger is usually a lease on a new bay, a new machine or a change of operation.

In Canada the two common commercial three-phase systems are 120/208 V and 347/600 V; the voltage guide explains where each is used. Many multi-tenant commercial buildings already have three-phase distribution, while older small buildings, some strip units and rural sites may have single-phase only. Three-phase at the building next door does not establish that it is available, or has capacity, at yours.

The buyers differ by building. A restaurant tenant needs it for a cooking line, a manufacturer for motors and drives, and a warehouse operator for conveyors and charging. The restaurant, industrial and manufacturing and warehouse pages describe those loads.

CCT 02Three routes to three-phase supply

There are three distinct scopes, and they carry different costs, approvals and limits.

1. A utility three-phase service. ENMAX extends three-phase supply to the site, usually with a new transformer, and the building gets new service entrance equipment. This is the only route that adds real capacity from the grid, and it involves ENMAX’s application, investment and scheduling.
2. Extending existing building distribution. Where the building already has three-phase, a new feeder from the main switchboard or a distribution panel can reach the bay or machine. In a 347/600 V building, a dry-type transformer steps down to 120/208 V for equipment that needs it. In a leased building this runs through the landlord’s switchgear and consent.
3. Conversion at the load. A phase converter or a variable frequency drive rated for single-phase input can run a particular three-phase motor from single-phase supply. It is a solution for specific machines, not a building supply, and the motor and machine manufacturers’ requirements decide whether it is acceptable.

Have the designer evaluate the actual motors and loads before comparing routes. A conversion that suits one lathe can be the wrong answer for a compressor, and a service upgrade that looks expensive can be cheaper than a string of converters when more equipment is coming.

CCT 03The ENMAX side: application, metering and investment

In Calgary, ENMAX Power owns the distribution system, and its answer about three-phase primary near the site shapes the whole project. Ask early: ENMAX does not confirm capacity when it reviews a circulated development permit ¹. The ENMAX commercial connection guide sets out the application sequence.

Metering. Services rated over 200 A must submit ENMAX’s CT request form and CT meter installation checklist ². The customer provides and owns the CSA-approved meter socket or enclosure ³, and ENMAX restricts contractors from handling meters ¹. The CT metering guide explains the cabinet and what the owner supplies.

Investment. ENMAX invests toward new load and the customer pays the rest as a contribution. For 2026 the small commercial (D200) investment is $14,675 per meter ⁴. Medium and large commercial customers may instead take $367 per kVA of minimum contract demand on a 15-year agreement, $245 on 10 years or $122 on 5 years, up to 80% of anticipated maximum demand ⁴. This is a credit, not a price, and the demand commitment is a contract the business must be able to keep.

The connection formula. When ENMAX modifies facilities for a changed service, the customer pays (A − B) + C − D + E + F: removal cost less salvage, plus installation, less ENMAX’s investment, plus prepaid O&M on optional facilities and other costs ⁵. Where ENMAX manages work estimated above $25,000, its estimate is broken down by component ⁵. ENMAX may decline to invest in a connection expected to be used for two years or less ⁵.

Service cables. ENMAX’s investment schedule notes that at 400 A or higher the customer supplies its own service cables ⁴. The note sits with the residential rows, so confirm in writing how ENMAX applies it to a commercial connection before the bid is closed.

Energization. The site must be approved by the inspection authority to ENMAX’s metering standard before it is energized, and energization is requested through the retailer ².

CCT 04Who does what on a three-phase project

A bid that is silent on any row has left it to someone. Ask each bidder to mark every row included, excluded or by others.

CCT 05Permits, drawings and the 600 A line

Only a master electrician can obtain the electrical permit in Alberta ⁶. Calgary requires plans and drawings for new construction or service upgrades of 600 A and higher, including every high-voltage installation ¹. At that size the single-line diagram or shop drawings must show fault current at every overcurrent device, the service characteristics and ratings, and any series-rated combinations ¹, so the designer needs ENMAX’s available fault current early.

Below 600 A the permit is still required, and base-building and tenant-space work take separate electrical permits ¹. The contractor permit fee is $112 plus $9.79 per $1,000 of construction value, plus the Safety Codes Council fee ⁷. The commercial permits guide covers plans review and inspections.

CCT 06What drives the cost, including lead time

The largest variables are distance to three-phase primary, the civil work to reach the site, the transformer and service equipment, and the customer contribution after ENMAX’s investment. Inside the building, feeder length and routing through occupied or third-party space often matter more than the equipment itself.

Equipment lead time is a cost driver in its own right. Transformers, switchboards and CT cabinets are built or allocated to order, and their delivery dates are set by suppliers and move with the market. A long lead time can mean paying rent on a space that cannot run, renting temporary equipment or generation, or mobilizing a crew twice. Record the quoted lead time on each supplier quotation, compare it across bids, and confirm it again before booking the utility and the shutdown. Do not accept an unreviewed substitute simply because it ships sooner.

The three-phase power cost guide sets out the drivers in detail. To relate kW, kVA and amps at 208 V or 600 V, or to see the next standard transformer size, use the three-phase kVA calculator; it shows arithmetic only and does not size conductors or protection.

CCT 07Cut-over, shutdowns and energized equipment

Most three-phase projects end with a cut-over: the old supply is disconnected, the new service is inspected and ENMAX energizes it. ENMAX needs at least 3 business days’ notice for disconnect and reconnect work ⁸. Work it schedules outside 7:00 a.m. to 4:00 p.m. on weekdays is billed at $352 per hour ⁹, and meter upgrades are billed at $128 per hour single-phase or $258 per hour multi-phase, plus materials ⁹. Where the change affects an existing switchboard, the switchgear and transformers scope and a planned outage come into play; a pure capacity increase is covered under commercial service upgrades.