Whether you are fitting out a new retail unit on Yonge Street, converting warehouse space in North York, or expanding a restaurant kitchen in Vaughan, commercial electrical installation follows a very different set of rules than residential work. The loads are heavier, the inspection requirements are stricter, and the cost of getting it wrong is measured in closed doors and lost revenue rather than a tripped breaker.
This guide walks Toronto and GTA business owners through what a commercial electrical installation actually involves, what the Ontario Electrical Safety Code (OESC) requires, and how to plan the work so your opening date does not slip.
How Commercial Electrical Work Differs from Residential
Most homeowners deal with a 120/240V single-phase service. Commercial buildings frequently run on three-phase power — typically 120/208V or 347/600V — because motors, rooftop HVAC units, commercial refrigeration, and elevator equipment run far more efficiently on it. That single difference cascades through the entire installation.
- Heavier service capacity. A commercial kitchen or machine shop can draw more current from one piece of equipment than an entire house does at peak.
- Conduit instead of loose cable. Commercial wiring is generally run in EMT, rigid conduit, or armoured cable rather than the NMD90 used in homes, so it can be inspected, protected, and modified later.
- Life-safety systems. Emergency lighting, exit signage, fire alarm circuits, and in many occupancies emergency power all have dedicated requirements.
- Occupancy-driven rules. A daycare, a medical clinic, and a warehouse are held to different standards even in the same building shell.
- Business continuity. Work often has to be staged around trading hours, which changes how the job is sequenced and priced.
A Typical Commercial Installation, Step by Step
1. Load Calculation and Systems Design
Everything starts with an honest load calculation. A licensed electrician totals the connected load of your lighting, receptacles, HVAC, kitchen or production equipment, and any EV charging you plan to add, then applies the demand factors the OESC allows. This determines whether your existing service is adequate or whether you need a service upgrade before anything else can be scheduled. Our electrical systems design team handles this stage, producing the drawings and panel schedules an inspector and a general contractor both need.
2. Permits and ESA Notification
Commercial electrical work in Ontario requires a permit — an ESA notification — filed by a Licensed Electrical Contractor before the work begins. Depending on scope you may also need a building permit from the City of Toronto or your local municipality, and larger service changes require coordination with the local distribution utility. Skipping the permit is the single most expensive mistake a business owner can make: unpermitted work commonly surfaces during a lease assignment, a sale, or an insurance claim, and it has to be opened up and re-inspected at that point.
3. Service Entrance and Distribution
If the load calculation shows you need more capacity, the service entrance, main disconnect, and distribution panels are upgraded first. Utility coordination is the long pole here — allow lead time for it. Related work often includes new subpanels for a specific tenant area or department, and metering if you need to bill separate units. See our electrical panel upgrade and service upgrade and remodelling pages for how that work is scoped.
4. Rough-In
Conduit, boxes, and cable are installed before walls and ceilings close. This is the stage where good design pays for itself — adding a circuit during rough-in is inexpensive, while adding it after drywall and finishes means cutting and patching. Our electrical systems installation crews coordinate rough-in with the mechanical and framing trades so nothing has to be pulled back out.
5. Rough-In Inspection
An ESA inspector reviews the concealed work before it is covered. Book this into your schedule rather than treating it as an afterthought; a failed rough-in inspection can hold up drywall for the whole project.
6. Finish and Final Inspection
Devices, lighting fixtures, panel labelling, and equipment connections go in, followed by testing and the final ESA inspection. You receive a Certificate of Acceptance — keep it. Landlords, insurers, and future buyers all ask for it.
What Drives the Cost of a Commercial Installation
There is no flat rate for commercial electrical work, and any contractor who quotes one before seeing the space is guessing. The real variables are:
- Existing service capacity — whether you can work within it or need a full service upgrade
- Square footage and circuit count — how much conduit, wire, and labour the layout demands
- Occupancy type — food service and health care carry requirements a general office does not
- Building age and construction — concrete and masonry are slower to work in than steel stud
- Scheduling constraints — after-hours or phased work to keep you trading costs more than an empty shell
- Utility and permit lead times — these affect the schedule more than the invoice, but they affect your revenue either way
Cost depends on your service size, occupancy type, and scope of work. Call us at +1 (647) 832-3800 for a free site visit and written estimate rather than working from a number you found online.
Practical Tips for Business Owners
- Get the electrician involved before you sign the lease. An hour of assessment can tell you whether the unit can actually support your equipment — far cheaper than discovering it afterwards.
- Plan capacity for five years, not opening day. Spare breaker spaces and empty conduit runs cost very little during construction and a great deal later.
- Ask about EV charging early. If you are considering staff or customer charging, the time to size the service for it is now. See our commercial and residential EV charger installation page.
- Keep the panel schedule current. Every time a circuit changes, update the directory. During an outage this turns a long search into a thirty-second fix.
- Schedule maintenance, do not wait for failures. Warm breakers, loose terminations, and worn devices are found on inspection long before they cause downtime. Our switches and outlets maintenance service covers this.
- Know who to call at 2 a.m. Establish the relationship before the emergency, not during it.
Frequently Asked Questions
Do I need a permit for commercial electrical work in Ontario?
Yes. Nearly all commercial electrical installation, alteration, and repair work requires an ESA notification filed by a Licensed Electrical Contractor before work starts. Depending on scope, a municipal building permit may also apply. A legitimate contractor files the notification as part of the job — if one suggests skipping it, treat that as a reason to look elsewhere.
How long does a commercial electrical installation take?
It depends almost entirely on scope and on utility lead times rather than on the wiring itself. A small retail fit-out within the existing service is a matter of days; a full service upgrade with utility coordination and multiple inspection stages runs considerably longer. We give you a realistic schedule with the estimate, including the inspection milestones, so you can plan your opening around it.
Can you do the work without closing my business?
In most cases, yes. We regularly phase commercial work into after-hours and overnight shifts, or stage it area by area so part of the space stays operational. Some steps — a main service changeover, for example — require a planned shutdown, but that window can usually be scheduled for your slowest trading period.
What is three-phase power and do I need it?
Three-phase power delivers energy over three alternating conductors instead of one, which lets motors and large equipment run more efficiently and with smaller conductors. If you operate commercial HVAC, refrigeration, elevators, or production machinery, it is often required by the equipment itself. A load calculation will tell you definitively.
What happens if I inherit unpermitted electrical work in a leased space?
Have it assessed by a licensed electrician before you take occupancy. Unpermitted work can usually be brought into compliance, but the cost and responsibility for doing so is a lease negotiation point — and a far better one to raise before you sign than after.
Work with Licensed Electricians Across the GTA
North York Electricians has served Toronto and the Greater Toronto Area for over 20 years, with a team of more than 30 licensed electricians handling commercial and residential work in North York, Vaughan, Markham, Richmond Hill, Brampton, Mississauga, and Oakville. Every installation we complete is done to the Ontario Electrical Safety Code and inspected by the ESA.
Planning a fit-out, expansion, or service upgrade? Call +1 (647) 832-3800 for a free estimate, or get in touch here. If you are dealing with a power failure or an electrical hazard right now, our 24/7 emergency electrician service is available around the clock.