Not every isolation transformer belongs in a clean, climate-controlled electrical room. Outdoor equipment, corrosive facilities, dusty plants, washdown areas,...
Transformer Solutions
for Construction Projects
Construction sites demand power that keeps pace with the project — from temporary site power in the early stages of a build to permanent distribution transformers installed as part of the finished electrical system. Transformer Source supplies contractors, electrical engineers, and project managers with in-stock dry-type transformers that ship fast and arrive site-ready.
- CSA & UL Certified
- Ships from Canadian Stock
- 3 kVA – 1,000 kVA Range
- Custom Configurations Available
Powering Construction Sites & Infrastructure Projects
Construction electrical requirements span two distinct phases: temporary site power during the build, and permanent distribution transformers that become part of the completed facility. Both have critical timing requirements — a delayed transformer delivery can hold up an entire project schedule — and both must meet CSA certification requirements enforced by the authority having jurisdiction (AHJ) on every Canadian job site.
Transformer Source maintains in-stock inventory of the most common construction transformer sizes and ships quickly from our Canadian warehouse. Whether you’re a general contractor needing a temporary power transformer for a high-rise pour, an electrical contractor specifying the permanent distribution for a multi-tenant building, or an infrastructure engineer designing a substation for a road or transit project — we have the unit and the technical support to get it right.
Key Construction Power Challenges We Solve:
- Temporary site power: Step-down transformers for construction hoists, tower cranes, site trailers, and temporary lighting from a 600V site service
- Schedule pressure: In-stock units ship in 1–3 business days — no project delays waiting on custom lead times for standard sizes
- Outdoor and site conditions: NEMA 3R enclosed and weatherproof units for exposed site installations and temporary power pedestals
- Permanent building distribution: Floor-by-floor isolation transformers installed during construction become part of the permanent electrical system
- Voltage conversion for site equipment: Adapting imported construction equipment (cranes, welders, concrete equipment) rated at 400V or 460V to Canadian 600V site power
- Infrastructure projects: Transformers for temporary and permanent power on road, transit, utility, and civil construction projects
- Motor starting: Reduced-voltage starting for large construction hoists, concrete mixers, and pumps on site
Construction Sectors We Serve:
- High-Rise Residential & Commercial Construction
- Industrial Facility Construction & Plant Expansions
- Infrastructure: Roads, Bridges & Transit Projects
- Institutional: Hospitals, Schools & Government Buildings
- Multi-Unit Residential Developments
- Retail & Mixed-Use Development
- Utility & Substation Construction
- Mining & Resource Project Construction
- Renovation, Retrofit & Tenant Improvement Projects
Recommended Transformers for Construction
The following transformer types are most commonly specified for construction site power and permanent building distribution. Filter by kVA, voltage, or enclosure using the product search.
Isolation Transformers
3kVA to 750kVA Capacity
Encapsulated Isolation Transformers
0.25kVA to 150kVA Capacity
Autotransformers
3kVA to 1000kVA Capacity
Encapsulated Autotransformers
3kVA to 300kVA Capacity
Control Transformers
25VA to 5000VA Capacity
Motor Starters
10HP to 500HP Capacity
Mini Power Centers
5kVA to 45kVA Capacity
Recommended Specifications for Construction
Use the following as a baseline reference for temporary and permanent transformer specifications on construction projects. Always confirm with the electrical engineer of record and the AHJ.
Temporary Site Trailer / Office | 15 – 45 kVA |
Construction Hoist (single) | 30 – 75 kVA |
Construction Hoist (twin / high-speed) | 75 – 150 kVA |
Tower Crane Supply | 45 – 150 kVA |
Temporary Lighting & Small Tools | 5 – 30 kVA |
Concrete Pump / Large Site Equipment | 30 – 150 kVA |
Permanent Floor Distribution (residential) | 15 – 75 kVA per floor |
Permanent Floor Distribution (commercial) | 75 – 225 kVA per floor |
Permanent Building Main Step-Down | 150 – 750 kVA |
Infrastructure / Substation Temporary Power | 75 – 500 kVA |
For temporary power, size at 125% of peak connected site load. For permanent installation, defer to the electrical engineer’s load schedule.
Primary (Input) | 600V or 575V, 3-phase (standard Canadian construction site service) |
Secondary — Site Trailers / Offices | 120/240V single-phase or 120/208V, 3-phase |
Secondary — Construction Hoists | 208V or 480V, 3-phase (confirm with hoist manufacturer) |
Secondary — Permanent Building Distribution | 120/208V, 3-phase, 4-wire (most common for commercial) |
Imported Site Equipment | 600V → 400V, 460V, or 208V as required by equipment nameplate |
Taps | ±2.5% and ±5% standard — useful for voltage fine-tuning on long site distribution runs |
NEMA 1 | Permanent indoor installations in completed electrical rooms |
NEMA 3R (Rainproof) | Outdoor temporary site power, exposed permanent locations, construction site pedestals |
Encapsulated | Below-grade construction areas, exposed outdoor temporary installations, permanent parking garage and loading dock locations |
NEMA 12 | Dusty indoor construction environments and permanent plant floor installations |
Weatherproof Canopy | Additional protection for NEMA 3R units in high-exposure Canadian outdoor sites |
Temporary Outdoor (Site) | NEMA 3R on housekeeping pad or temporary structure — verify wind and snow load for Canadian winter sites |
Temporary Indoor (Enclosed) | NEMA 1 acceptable once building is weather-tight; NEMA 3R until then |
Permanent Indoor | Dedicated electrical room — NEMA 1, with proper clearances per CEC |
Permanent Outdoor | NEMA 3R minimum on permanent concrete pad with appropriate drainage |
Cold Weather | Canadian winter construction requires units rated for cold-temperature startup — specify if installation occurs before building is heated |
Clearances | 36″ front, 18″ sides minimum — critical to plan for in construction scheduling |
Canadian Standard | CSA C22.2 No. 47 — mandatory; AHJ will enforce on all Canadian job sites |
Electrical Safety Authority | ESA approval required in Ontario; verify with local AHJ in all provinces |
CEC Part I | Canadian Electrical Code governs both temporary and permanent installation requirements |
UL Listed | Required for any transformer shipped to or used on US job sites |
Temporary Power | CEC Section 76 governs temporary wiring on construction sites — transformer must be CSA certified |
Seismic | BC and Alberta foothills projects — seismic rated mounting required for permanent installations |
Temporary Site Power | K-1 standard is generally acceptable — site loads are predominantly motor and resistive |
Permanent Commercial Distribution | K-4 minimum for mixed-use floors with office and retail tenants |
Permanent IT / Tech Tenant Floors | K-13 for floors with significant server, computer, or electronic load |
Construction Site with VFD Equipment | K-13 if significant VFD-driven equipment (modern tower cranes, hoists with VFD controls) is connected |
Permanent Data / Telecom Rooms | K-20 for any permanent transformer feeding server or telecom loads |
Cold Weather Startup | Canadian construction sites can see -30°C and below — verify cold-temperature ratings for outdoor winter installations |
Moisture & Rain | NEMA 3R or encapsulated for all outdoor and temporary site installations |
Dust & Debris | Active construction generates significant airborne dust — NEMA 3R or encapsulated to prevent internal contamination |
Vibration | Concrete pours, compaction equipment, and heavy machinery — specify vibration isolation pads for site-adjacent installations |
Temporary vs. Permanent | Temporary units may be redeployed across multiple projects — specify NEMA 3R and robust enclosures for durability |
Altitude | Mountain and high-elevation infrastructure projects (BC, Alberta) — derate above 1,000m |
Frequently Asked Questions — Construction
What transformer do I need for temporary site power on a construction site?
For most Canadian construction sites served by a 600V, 3-phase site service, a NEMA 3R enclosed isolation transformer or autotransformer stepping down to 120/208V or 120/240V is the standard solution for temporary power distribution. Size the transformer based on the peak connected load of site trailers, tools, lighting, and equipment — and add 25% headroom for startup surges. For construction hoists and tower cranes, consult the equipment manufacturer’s electrical requirements and size the transformer specifically for that load. All temporary site power transformers must be CSA certified — this is enforced by the AHJ on every Canadian job site.
Can I use the same transformer for temporary power and then leave it as permanent?
Yes — this is a common and cost-effective approach on many construction projects. Specifying a transformer that meets both the temporary site power requirements and the permanent building distribution specification eliminates the cost and schedule of swapping out a temporary unit. The key is ensuring the transformer meets the permanent installation specifications: correct kVA, voltage, enclosure type, and CSA certification for the permanent application. A NEMA 1 isolation transformer with the right voltage and kVA can serve as temporary power once the building is weather-tight, then remain in place as the permanent floor distribution transformer.
What size transformer do I need for a construction hoist?
Hoist transformer sizing depends on the specific hoist model, capacity, and speed. As a general guide, a single single-cage construction hoist (commonly 2–5 tonnes, 600V) requires a 30-75 kVA transformer; a twin-cage or high-speed hoist may require 75–150 kVA. The hoist manufacturer’s electrical specifications will specify the minimum transformer kVA, primary and secondary voltages, and recommended short-circuit current capacity. Always confirm with the hoist supplier before ordering. Under-sizing a hoist transformer causes voltage sag, nuisance tripping, and reduced hoist performance. If the site has multiple hoists, do not share a single transformer unless it is explicitly sized for the combined load.
How quickly can you deliver a transformer to a construction site?
Standard isolation transformers, autotransformers, and encapsulated units in common construction kVA sizes (15, 30, 45, 75, 112.5, 150, 225 kVA) are stocked and typically ship within 1–3 business days from our Canadian warehouse. For projects with tight schedules, confirm stock availability when you contact us — we will give you an honest answer on what is on the shelf. Custom voltages, large kVA sizes above 500 kVA, and special enclosures have lead times of 4–12 weeks. Electrical contractors on active sites can call us directly for fast turnaround on urgent requirements.
Do I need a CSA certified transformer for a construction site in Canada?
Yes — without exception. All transformers installed on Canadian construction sites, whether for temporary or permanent use, must bear a valid CSA certification mark. The authority having jurisdiction (AHJ) — typically the provincial electrical safety authority — will require CSA certification as part of the electrical inspection process. Non-certified equipment will not pass inspection and will need to be replaced, causing costly project delays. All Transformer Source units are CSA certified, and we provide full certification documentation with every order.
What transformer do I need for an imported tower crane rated at 400V?
European tower cranes are rated for 400V, 3-phase, 50/60 Hz — which requires a step-down transformer from a Canadian 600V site service. An autotransformer with a 600V primary and 400V secondary, sized at 125% of the crane’s nameplate kVA, is the most common and economical solution. If the crane’s electrical documentation specifies galvanic isolation or if the crane has a built-in 230V single-phase control circuit, an isolation transformer is the better choice. Transformer Source stocks autotransformers in ratings commonly used for tower crane applications — contact us with the crane’s electrical data sheet for a specific recommendation.
What enclosure do I need for an outdoor construction site transformer?
NEMA 3R Outdoor (rainproof) is the minimum enclosure rating for any outdoor construction site installation in Canada. NEMA 3R Outdoor protects against rain, sleet, and external ice formation. For sites with significant dust, debris, or high-pressure wash exposure, an encapsulated transformer provides better protection. In winter conditions where the transformer will be exposed to snow accumulation or freeze-thaw cycles, ensure the enclosure has proper drainage and consider a weatherproof canopy for additional protection. Never install a standard NEMA 1 transformer outdoors — it provides no weather protection and will fail.
Can you supply transformers for infrastructure and civil construction projects?
Yes — Transformer Source supplies transformers for road, bridge, transit, utility, and civil construction projects across Canada. Infrastructure projects often require larger kVA sizes for temporary power to tunnel boring equipment, pumping stations, and construction camps, as well as permanent transformers for substations, transit facilities, and utility infrastructure. We work with electrical engineers, prime contractors, and subcontractors on project-specific requirements. For large infrastructure projects with multiple transformer requirements, contact us for project pricing and delivery scheduling.
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Ready to Order Your Construction Transformer?
Fast delivery, CSA certification, and technical support for every project stage — from temporary site power to permanent building distribution. Call us with your spec and we’ll tell you what’s on the shelf today.
Have this information ready:
- Temporary or permanent installation
- Required kVA and connected load (or equipment list)
- Primary voltage from site service (600V, 575V, 480V)
- Required secondary voltage
- Outdoor or indoor installation (enclosure requirement)
- Project location and delivery address
- Required delivery date