Industrial electrical systems operate at voltages and power levels that are fundamentally different from residential and light commercial installations. While your home runs on 120/240V single-phase power, industrial facilities in Ontario typically use 347/600V three-phase power — a system designed to efficiently deliver the massive amounts of energy required by manufacturing equipment, processing systems, and heavy machinery.
Understanding these systems is important for facility managers, plant engineers, and business owners who depend on reliable industrial power. This article provides a clear overview of how industrial electrical works in Ontario and why it requires specialized expertise.
Why 347V/600V? The basics of industrial power
Higher voltage means lower current for the same amount of power delivered. Lower current means smaller wire sizes, reduced energy losses in transmission, and more efficient motor operation. For a factory running hundreds of kilowatts of equipment, the savings in conductor sizing, energy efficiency, and equipment performance make high-voltage distribution essential — not optional.
In Ontario, the standard industrial voltage configuration is 347/600V three-phase, four-wire. The 600V is used for motor loads and heavy equipment, while 347V (phase-to-neutral) is commonly used for high-bay lighting in warehouses and manufacturing floors. Step-down transformers within the facility convert to 120/208V for general-purpose receptacles, office areas, and control systems.
Three-phase power: why industrial loads need it
Three-phase power delivers energy using three alternating current waveforms offset by 120 degrees. This provides a constant, smooth power delivery — unlike single-phase, which pulsates. Electric motors running on three-phase power are smaller, more efficient, and longer-lasting than their single-phase equivalents at the same horsepower rating. For any motor over about 5 HP, three-phase is the standard.
Three-phase systems also balance the electrical load across three conductors, reducing the neutral current and improving overall system efficiency. This is why industrial facilities, large commercial buildings, and data centres all use three-phase power distribution.
Transformers: the bridge between voltage levels
Industrial facilities use transformers to step voltage up or down as needed within the facility. The utility delivers power at high voltage (often 13.8kV or 27.6kV in Ontario) to a pad-mounted or vault transformer outside the facility, which steps it down to 600V for distribution. Inside the facility, dry-type transformers step 600V down to 120/208V for receptacles and light-duty loads.
Transformer maintenance is critical in industrial settings. Oil-filled transformers require regular oil testing and analysis. Dry-type transformers need periodic cleaning and thermal inspection. A transformer failure in an industrial facility can mean weeks of downtime while a replacement is manufactured, shipped, and installed.
Safety and qualifications for high-voltage work
Working on 347/600V systems is inherently more dangerous than residential electrical work. Arc flash hazards at industrial voltages can cause severe burns, blast injuries, and fatalities. Ontario's Occupational Health and Safety Act requires arc flash hazard assessments, proper personal protective equipment (PPE), and specific training for workers exposed to electrical hazards. CSA Z462, Workplace Electrical Safety, provides the standards for arc flash risk assessment and PPE selection.
Not every licensed electrician is qualified or experienced in industrial high-voltage work. When selecting an electrical contractor for industrial projects, verify that they have specific experience with 347/600V systems, that their electricians hold the appropriate certifications, and that they follow a documented safety program including lockout/tagout procedures and arc flash protocols.
Arc flash incidents at 600V can produce temperatures exceeding 19,000 degrees Celsius and blast pressures that throw workers across rooms. This is not work for general-practice electricians. Demand industrial-specific qualifications and safety programs.
Safer Electric's industrial division handles 347/600V systems, transformer installations, motor control centres, and arc flash assessments for facilities across the GTA. Our industrial electricians are CSA Z462 trained and carry the appropriate PPE for every job.
Safer Electric Team
Licensed Electricians · Toronto, ON
Our team of licensed GTA electricians writes these guides to help homeowners make informed decisions. Every article is reviewed for technical accuracy.