Why three-phase matters to a business
Most houses run on single-phase power. Most commercial and industrial buildings run on three-phase. If you are leasing a shop, opening a restaurant or buying a compressor, CNC machine or commercial oven, knowing which you have, and at what voltage, saves expensive surprises.
Three-phase supplies power as three alternating currents, each offset by a third of a cycle. The result is smoother power with no dead spots. Motors run more efficiently and start more easily, and for the same power the wire can be smaller.
Voltages you will see in Alberta
| System | Where you find it | Typical uses |
|---|---|---|
| 120/240 V single-phase | Houses, small strip-mall units, some older shops | Lights, receptacles, small equipment |
| 120/208 V three-phase | Many retail units, offices, restaurants, apartment buildings | Receptacles at 120 V; HVAC, ovens and motors at 208 V |
| 347/600 V three-phase | Larger commercial, industrial and warehouse buildings | 600 V motors and equipment, 347 V lighting |
Other systems exist, especially in older or specialised buildings, so always confirm with the landlord, the building's electrical drawings or an electrician. The nameplate on the main switchboard is a good place to start.
The 208 V vs 240 V trap
This is one of the most common equipment problems in small businesses. Much commercial kitchen and shop equipment is sold in both 208 V and 240 V versions. A heating appliance built for 240 V will still run on 208 V, but at roughly three quarters of its rated output. Ovens take longer to heat, fryers recover slowly and heaters fall short in January.
Before buying equipment, confirm the building's voltage and phase and order the matching model. Motors and controls can be more sensitive than heaters, so check with the supplier as well as your electrician.
In a 347/600 V building, most 120 V and 208 V loads are fed through a step-down transformer and a separate panel. Large equipment may be available in a 600 V version that avoids the transformer altogether.
Balancing and planning panels
In a three-phase panel, single-phase loads are spread across the three phases so that each carries roughly the same current. A badly balanced panel can overload one phase while others sit idle, causing nuisance trips and overheating.
- Ask for a panel schedule that shows the load on each phase, not just a list of circuits.
- When adding equipment, let your electrician choose which breaker spaces to use.
- For larger additions, a load calculation confirms the panel and service can handle it.
- Keep spare capacity on each phase for future equipment.
If your space only has single-phase
Small units in older strip malls and converted buildings sometimes have only single-phase power. If your equipment needs three-phase, the options are:
- Bring three-phase from the utility. This depends on what is available on the street or in the building. In Edmonton, EPCOR is usually the wire owner; elsewhere it is often FortisAlberta or another distributor. Availability, distance and transformer work drive the cost and the timeline.
- Buy single-phase equipment where it exists, which is often the simplest answer for smaller machines.
- Use a phase converter or drive for specific motor loads, chosen and sized with the equipment supplier and your electrician.
Changing a building's service can take months and depends on the utility. Confirm the supply before signing a lease or committing to equipment.
Working with an electrician
Bring the equipment list with nameplate voltages, phases and amps, along with the building's switchboard and panel information. Alberta Electrical handles tenant improvements, motor controls and switchgear upgrades, including design, permits and coordination with the utility.
Expect your electrician to ask about the hours the equipment runs, whether loads start together (several compressors at opening time, for example) and whether any equipment is sensitive to voltage dips. Those details shape the breaker sizes, the wire and sometimes the choice of motor starter or drive.
For ongoing peace of mind, a scheduled commercial maintenance visit can include thermal scanning of the panel and a check of phase balance as your business grows.
For restaurants and retail spaces, our retail and restaurant electrical team plans kitchen equipment circuits with the right voltage from the start.
Common questions
How do I know if my building has three-phase?
Check the nameplate on the main switchboard or panel, the building drawings, or ask the landlord. Three-pole breakers in the panel are a strong hint. An electrician can confirm.
Can I run 240 V equipment on 208 V?
Heating equipment usually runs, but at reduced output. Motors and controls may not be suitable. Check with the supplier and order the matching voltage when you can.
Is 600 V dangerous to have in my building?
All electrical systems need respect. 600 V equipment is normal in Canadian commercial buildings and is installed and maintained by licensed electricians. Keep electrical rooms closed and clear.
Why does my panel have three-pole breakers?
Three-pole breakers feed three-phase equipment such as motors, compressors and larger HVAC units. They switch all three phases together.
How long does it take to get three-phase service?
It depends on the utility, what is available nearby and the work involved. It can take months, so start early.
Codes and permit rules change and every building is different. For work on your system, talk to a licensed electrician and your local permit authority.