Commercial Rewiring in Hamilton: Doing It Without Closing

By Zvonko Lipovac, Master Electrician, Apollo Electric Inc. · ECRA/ESA 7009372 · Last updated: 5 October 2026

Commercial rewiring is bought on downtime, not on cable. Any licensed contractor can pull conductors. What separates the quotes is whether the plan lets you keep trading, keeps your life safety systems lawful while the work runs, and leaves you with the documentation your insurer and your landlord will both ask for.

Apollo Electric Inc. has worked on commercial and industrial buildings across Hamilton since 2012, and Zvonko Lipovac has over 30 years in the trade under ECRA/ESA licence 7009372. This page covers how the work is sequenced in an occupied building, the life safety constraint that governs the schedule, and the lease question that decides who pays.

Why It Is Not a Big House Rewire

Commercial rewiring and a house rewire share their methods. Almost nothing else.

	House	Commercial building
Supply	Single phase, one service	Often three phase, sometimes multiple services and house panels
Occupancy	One family, can move out	Staff, tenants, customers, often around the clock
Life safety	Interconnected smoke and CO alarms	Monitored fire alarm, emergency lighting, exit signs, all code-governed
Method	Cable fished through finished walls	Conduit, cable tray and raceway above accessible ceilings
Who decides	The owner	Landlord, tenant, insurer and sometimes a franchisor
Downtime	Inconvenient	Measured in lost revenue per hour

That last row is why commercial rewiring is planned backwards from the schedule. You start with the hours the building can lose and design the sequence to fit them, rather than designing the installation and discovering the disruption afterwards. A contractor who quotes without asking about your trading hours has not thought about the part that costs you most.

If the building work is residential rather than commercial, the constraints are completely different and we cover those under home rewiring instead.

How Is Commercial Rewiring Done Without Closing?

By treating the building as a series of zones rather than one job. The sequence we use on occupied premises runs like this.

1. Survey and load study. What is actually connected, what the service can carry, and what the new use needs. On older Hamilton buildings this routinely finds circuits nobody can account for.
2. Zone the building. Floor by floor, suite by suite, or front of house and back of house, so each zone can be taken out and returned independently.
3. Notification of work filed with the Electrical Safety Authority before anything starts. The contractor files it, never the tenant.
4. New distribution installed live alongside the old. This is the core of it. New panels and feeders go in while the existing system keeps running, so nothing is switched until its replacement is ready.
5. Zone cutovers, out of hours. Each zone transfers to the new distribution in a window the business can lose, then is tested and energised before the window closes.
6. Life safety kept continuous. Fire alarm and emergency lighting are migrated on their own sequence, with interim measures where required. See the next section.
7. Old distribution removed. Abandoned conductors left in place are a hazard to the next trade and a finding at the next inspection.
8. Inspection, documentation, panel schedules. You should end up with as-built schedules, not a cupboard full of unlabelled breakers.

Done this way, most buildings never close. Commercial rewiring becomes a series of short, planned windows rather than one long shutdown, which is almost always cheaper overall even when the labour line looks higher. The same discipline applies to any new installation work, where the load study comes before the equipment.

Fire Alarm and Emergency Lighting

This is the constraint that governs every other decision in commercial rewiring, and the one most quotes underprice.

A commercial building's fire alarm, emergency lighting and exit signage are code-governed life safety systems. They cannot simply be switched off for the convenience of a rewire, and in an occupied building the obligations do not pause because there is a contractor on site.

In practice that means three things on any commercial rewiring project:

• Life safety migrates on its own schedule, separate from the power distribution, and usually first or last rather than in the middle.
• Interim measures may be required while a zone is in transition, and those are planned and documented rather than improvised on the night.
• Verification follows the work. A fire alarm system altered during commercial rewiring needs its own testing and documentation, which is a separate specialism from the power work and a separate line on the quote.

Ask any bidder directly how they intend to handle the fire alarm and emergency lighting during the phasing. The answer tells you very quickly whether they have done occupied commercial rewiring before or only houses.

Landlord or Tenant: Who Pays for What

Who funds commercial rewiring is a lease question, not an electrical one. We are not lawyers, so treat this as the practical shape of it rather than a ruling on your lease.

In most commercial leases the split runs roughly along these lines, and your actual lease governs:

• Base building systems, the service, main switchgear, risers and house panels, typically sit with the landlord.
• Within the demised premises, the wiring serving the tenant's own fit-out typically sits with the tenant.
• Life safety systems are usually base building, even where the devices are inside a tenant's space.
• Improvements the tenant installs often become the landlord's at the end of the term, which changes the economics of who should fund them.

Two practical points. First, get the scope split written down before the work is ordered, because a dispute discovered mid-project stops the job. Second, whoever pays, the ESA notification is filed by the contractor and the documentation should reach both parties.

What Usually Forces the Decision

Nobody orders commercial rewiring on a working building for fun. One of these six is almost always behind the call.

1. A change of use. Retail becoming a restaurant, offices becoming a gym, warehouse becoming light manufacturing. New use, new load, new requirements.
2. An insurer's condition at renewal, often after an inspection flags the age or condition of the distribution.
3. Capacity. The building runs out of service before it runs out of space, which is common as electric heating, EV charging and IT load are added.
4. Condition. Deteriorated conductors, overloaded panels, obsolete breakers nobody can source.
5. A failed inspection or an incident. The most expensive moment to start planning.
6. A new tenant's fit-out, where the existing distribution cannot support what they intend to do.

If your trigger is capacity rather than condition, the answer may be a service and distribution upgrade rather than a full rewire. That is a cheaper conversation and worth having first, and it overlaps with our commercial electrical services and with plant floor work where the building is industrial.

What Moves the Price

We price commercial rewiring after a survey, because the spread between two buildings of the same floor area is enormous. These factors drive it, in order of impact:

• Occupied or vacant. The single biggest variable. Out of hours work, zone cutovers and protection of trading areas all cost real money.
• Ceiling access. Accessible tile ceilings versus hard plaster or exposed heritage finishes.
• Life safety scope. Whether the fire alarm and emergency lighting are in the project or already compliant.
• Service capacity. Whether the existing service stays or the whole supply is upgraded.
• Hazardous or special locations, commercial kitchens, wet areas, workshops, each with their own requirements.
• Heritage constraints, which in parts of Hamilton genuinely limit how and where conduit can be run.

Hamilton Buildings and What They Hide

Hamilton's commercial stock is unusually varied for a city its size, and each type brings its own surprise to a commercial rewiring survey.

The downtown core along King and James carries pre-war buildings with upper floors that were offices, then apartments, then offices again, each conversion adding distribution without removing the last. Industrial conversions in the north end and along Barton often have three phase supplies sized for machinery that left decades ago, which is either a gift or a liability depending on its condition. The Mountain's plazas and the business parks out toward Stoney Creek are newer and usually sound, but were built to the minimum provision of their day and run short the moment a tenant arrives with real load.

The local distributor for Hamilton, Dundas, Ancaster, Stoney Creek and Waterdown is Alectra Utilities, and its 24 hour line is 1-833-253-2872. That matters on any project touching the service, because the disconnection and reconnection is theirs to schedule and it has to be booked into the phasing rather than assumed. For a downed line, stay back at least 10 metres and call 911 first.

If you are weighing a commercial rewiring project, the survey is the thing to book first. Get in touch or call 905-921-5487 and we will tell you what the building actually has before anyone quotes on what it needs.

Frequently Asked Questions

Does commercial rewiring mean closing the business?

Usually not. In an occupied building the work is zoned, new distribution is installed alongside the existing system, and each zone is transferred during a window the business can lose, often overnight or at a weekend. Full closure is normally reserved for vacant premises or a change of use that stops trading anyway.

How long does commercial rewiring take?

It depends far more on access and occupancy than on floor area. A vacant unit with accessible ceilings can run a few weeks. An occupied multi-tenant building phased into out-of-hours windows can run several months of calendar time for the same quantity of work, because the available hours are limited.

Who is responsible for rewiring, the landlord or the tenant?

Your lease governs. As a general shape, base building systems such as the service, main switchgear and risers usually sit with the landlord, while wiring serving the tenant's own fit-out usually sits with the tenant, and life safety systems are usually base building. Get the scope split agreed in writing before work is ordered.

Can the fire alarm be switched off during a rewire?

Not casually. Fire alarm, emergency lighting and exit signage are code-governed life safety systems and an occupied building's obligations continue while work is under way. They are migrated on their own planned sequence with documented interim measures, and altered systems need their own verification and paperwork afterwards.

Do I need ESA notification for commercial rewiring?

Yes, and the Licensed Electrical Contractor files it with the Electrical Safety Authority before the work starts, not you. If a contractor asks you to file the notification in your own name, the regulator treats that as a sign they may not be licensed. Keep the resulting documentation for your insurer and your landlord.

Does Apollo Electric do commercial rewiring in Hamilton?

Yes. Apollo Electric Inc. is a Licensed Electrical Contractor under ECRA/ESA licence 7009372, WSIB compliant, serving Hamilton, Stoney Creek, Ancaster, Dundas, Burlington and the surrounding area. We survey first, phase the work around your trading hours, and hand over as-built panel schedules and inspection documentation.

References

• Electrical Safety Authority, finding the right contractor, on notification of work and who is required to file it.
• Electrical Safety Authority, hiring an electrician or contractor, on why only a Licensed Electrical Contractor may be hired.
• Alectra Utilities, Hamilton's distributor, its 24 hour line and the 10 metre stay-back distance.
• Government of Ontario, fire safety, on the Ontario Fire Code and building fire safety obligations.
• CSA Group, on certification of equipment installed in commercial premises.