A Hamilton shop owner calls in January because the new CNC mill the company financed in December does not run on the existing service. The 100A 240V single-phase service that was fine when the building was a body shop will not feed a 25 HP spindle motor, a dust collector, a compressor, and a couple of welders. The conversation shifts to three-phase, and then quickly to 600V three-phase, and then to what the panel layout, the transformer, and the Alectra service application actually look like. This post is the version of that conversation we have before the engineering drawings get drawn. It is the part the owner needs to understand to make good decisions, not the part the consulting engineer will stamp.
Why 600V three-phase is the answer for many small shops
The Canadian utility standard for commercial and industrial service offers a few voltage choices. For a small shop or light-manufacturing site the practical options are:
- 120/208V three-phase (often called 208 wye). The default for small commercial — strip-plaza retail, light office, food service. Receptacles get 120V, three-phase motors get 208V. Works for motors up to maybe 25 HP comfortably; gets expensive past that because the current draw climbs.
- 347/600V three-phase (often called 600 wye). The industrial workhorse. Lighting and receptacles run off a step-down transformer to 120/208V. Big motors get fed 600V directly. The current draw for a given horsepower is roughly a third of what it would be at 208V — which means smaller conductors, smaller breakers, and meaningfully less material across the building.
- 240V three-phase delta with high-leg, or 480V. Less common in Ontario commercial. Not the default conversation for a Hamilton-corridor shop.
The rule of thumb that holds across most of our work: if the building has motor loads over about 25 HP, or if the total connected load is north of about 200A at 208V, the math starts to favour 600V. Below that, 120/208V is usually the right choice and the savings on the transformer side beat the savings on the conductor side.
When 600V is actually the right call
We see this conversation in roughly three scenarios:
- The shop is moving from a single-phase residential-style service into a real commercial site. A custom fabrication shop in Stoney Creek that grew out of the owner's garage, now running CNC, plasma table, mig and tig welders, a paint booth, and a 7.5 HP air compressor. The 200A 240V single-phase service is at limit. The realistic answer is a service increase, and at this scale 600V three-phase is often the right scale to go to.
- The site is expanding and the existing 208V service is at limit. A Hamilton machine shop with 600A at 208V is at the point where the next motor addition triggers a major reconfiguration. Upgrading to 600V three-phase usually reduces the service-entrance amperage rating (because watts are watts, and watts at 600V are fewer amps) — sometimes the upgrade is to lower amperage at higher voltage, which catches the utility's interest because the conductor and breaker scale shrinks.
- A new build is going in and the electrical engineer is sizing the service from scratch. If the building is going to house any meaningful motor or process load, the engineer will spec 600V from day one. The owner's only job in that scenario is understanding why the recommendation is what it is.
The case where 600V is the wrong answer: a small retail or service business with no significant motor load and connected demand below about 100A at 208V. The transformer cost, the distribution cost, and the maintenance cost of a 600V service exceed what you save on the conductor side. We have had owners pushed toward 600V by a vendor selling a single piece of 600V-only equipment when the right answer was to spec the equipment differently or run a small dedicated transformer for that one machine.
Transformer placement — the decision that gets made early
The 600V service feeds the panel at 600V. Lighting, receptacles, and small motors run at 120/208V (or 347V single-phase for some lighting), fed from a step-down transformer somewhere in the building. Where that transformer sits is one of the layout decisions that has consequences for years:
- Pad-mounted outside (utility-owned). Some utility configurations put the step-down transformer outside on a pad, owned and maintained by Alectra (or Burlington Hydro, Oakville Hydro, depending on location). The building sees only the 120/208V side for non-process load. Cleaner on the customer side, but the utility has to support the configuration.
- Customer-owned dry-type transformer inside. More common. A 75 kVA, 150 kVA, or 225 kVA dry-type transformer mounted inside the building, usually in an electrical room or a corner near the main switchboard. The 600V comes in, the 120/208V goes out to the lighting and receptacle panels.
- Multiple smaller transformers per zone. Larger buildings sometimes use a smaller transformer at each end of the building rather than running 120/208V the length of the structure. Conductor savings on the 120/208V side offset the second transformer. Engineering decision.
The transformer placement also drives the noise question. A 150 kVA dry-type transformer hums. If it sits next to the office wall, the office hears it. If it sits next to the production floor, nobody notices. Plan it before the walls go up.
Distribution panel layout — the part the owner sees
After the service entrance and the main 600V switchboard, the building has a hierarchy of panels:
- Main switchboard at 600V. Service-entrance breaker, surge protection, branch feeds to the major loads — large motors, the step-down transformer to 208V, any 600V process equipment.
- Step-down transformer (dry-type or pad-mounted). 600V primary, 120/208V secondary. Sized to the connected load on the 208V side with future-growth headroom.
- 208V distribution panel. Lighting, receptacles, office HVAC, anything that does not need 600V.
- Motor control centre (MCC) or individual motor disconnects. For shops with multiple medium-to-large motors, an MCC consolidates the motor starters and overloads into a single piece of equipment. For smaller shops, individual disconnects at each motor are simpler.
The MCC versus individual-disconnect question is often the right place for owners to push back on a consulting engineer. An MCC is elegant and expensive. Three or four individual motor disconnects with their starters are clunky and cheap. Most small shops we wire do not need an MCC and the engineer's first instinct is sometimes to spec one anyway. Ask the question.
Motor loads, VFDs, and what is changing in 2028
Most of the larger motors in a modern small shop are now run through a variable-frequency drive (VFD). A 25 HP CNC spindle that fifteen years ago would have started directly across the line now starts via a soft-start ramp through a VFD, runs at variable speed under control logic, and draws much less startup inrush. From the service-sizing perspective, VFDs are mostly good news — the peak current draw at startup drops dramatically, which often means a smaller service can handle a given motor population than the same population on direct-starting contactors would have needed.
What VFDs introduce is harmonic distortion on the line. A shop full of VFDs feeding back harmonics into the 600V bus can trigger nuisance trips, transformer overheating, and in extreme cases utility-side notifications. Modern VFDs handle this through built-in line reactors and active front ends; older or no-name VFDs do not. When we spec a new build or a major retrofit, we look at the VFD population as a whole, not as individual motor sizes.
Other motor-related considerations to plan around:
- Soft starters versus VFDs. Soft starters give you reduced inrush but not variable speed. Cheaper than a VFD. For motors that only need to start gently but always run at full speed (some compressors, some pumps), the soft starter is the right tool.
- Power factor correction. Large motor loads without correction drag the power factor down and the utility charges for it on commercial accounts. A capacitor bank at the main switchboard is a small investment for a meaningful operating saving on most shops over about 200A at 600V.
- Motor disconnect within sight. OESC requires a disconnecting means within sight of every motor unless the motor disconnect is locked. The MCC does not satisfy "within sight" by itself; the layout has to put the disconnect at the motor.
ESA permit and utility coordination for a service increase
The paperwork side of a 600V service install or upgrade is the longest single timeline in the project. Plan for:
- Engineering drawings. Most utilities require sealed engineering drawings for a 600V service application. The drawings include the single-line, the load calculation, the equipment specs, and the site plan. A consulting engineer typically takes four to eight weeks from initial site visit to sealed drawings.
- Utility application (Alectra, Burlington Hydro, Oakville Hydro depending on location). The application includes the sealed drawings, the load demand, the service voltage request, and a payment for the connection charge. The utility's engineering review runs four to twelve weeks depending on workload and whether they have to upgrade the line feeding the site.
- ESA permit. The permit is in the LEC's name. Filed before the work starts. The ESA inspector visits at rough-in (before equipment is buried or boxed in) and at final.
- Equipment lead times. Switchgear and large dry-type transformers run on lead times that have not normalized since 2022. Twelve to twenty weeks from order to delivery is typical for switchboards in 2028. The order needs to land at the right point in the schedule so that the gear arrives when the building is ready for it.
- Coordination meeting at rough-in. The LEC, the engineer, the ESA inspector, and the utility's commissioning crew all need to be aligned on the final connection. Most service-increase projects have a single half-day commissioning meeting that locks in everyone's schedule.
From the owner's perspective: from the day the project is approved to the day the new service is energized is rarely less than four months and is often six to nine months. The longest pole in the tent is utility scheduling, not contractor work. If you are buying equipment now that needs a 600V service, start the application now.
What to plan for if the line is going up later
Some sites get a 600V service installed knowing that an addition or a second phase is two or three years away. The right way to plan for that:
- Size the main service for the future demand, not the current demand. The marginal cost of a larger transformer and larger switchgear at install time is smaller than the cost of replacing it later. Utilities resist sizing-up-from-day-one less than they resist returning for an increase eighteen months later.
- Leave spare conduit pathways. Conduit runs to the future panel locations, capped and labelled. Pulling wire later is cheap. Trenching later is expensive.
- Spec the switchboard with future feeder spaces. An extra 400A feeder breaker space in the main switchboard costs a small fraction of what it costs to add the feeder later as a tap.
- Document the original engineering on file at the site. The next engineer touching the building should not have to redo the load calculation.
The owner's job versus the engineer's job
The engineering is the engineer's. The decisions are the owner's. The owner needs to be able to answer, before the engineer shows up:
- What equipment is going in the building, name and HP rating of every motor over 5 HP.
- What the realistic operating duty cycle looks like. All motors running at once at full load is the design case, but it is rarely the real case.
- What the two-to-five-year growth picture is. Adding a second CNC, a paint booth, a second compressor — name what is likely.
- Whether the building HVAC is electric or gas. Electric HVAC is a meaningful chunk of the service sizing.
- Lighting type and quantity. LED fixtures with drivers are a small load; 1980s metal-halide is meaningfully larger.
Bring that list to the engineering meeting. The engineer's first hour is faster, the load calculation is more accurate, and the recommendation is grounded in the actual operation rather than a worst-case template.
When to call us
If you are sizing a new shop, expanding a Hamilton or Stoney Creek facility, or hitting the limit of your existing 208V service and weighing 600V, the early conversation matters more than the late one. We work with commercial and industrial-controls clients across the Golden Horseshoe — from the engineering coordination through Alectra or Burlington Hydro service application, the ESA permit, the switchgear order, and the commissioning. Bring us in before the engineer is hired and we will walk the building, sit down with your equipment list, and tell you what the realistic timeline and scope look like before any drawings are stamped. Request a site visit and let us look at the building with the load list in hand.