Commercial Electrical Services: What Business Owners Should Know

The Quick Answer

Commercial electrical systems differ significantly from residential systems in scale, complexity, and code requirements. Wisconsin businesses face stricter inspection requirements, different voltage configurations (three-phase power), and regulations that don't apply to homes. Whether you're opening a new business, renovating a commercial space, or managing ongoing maintenance, understanding these differences helps you plan better and avoid costly surprises.

Commercial vs. Residential: Key Differences

Voltage and Power Systems

Residential: Single-phase power, 120/240V, typically 100-200 amp service
Commercial: Three-phase power, 120/208V or 277/480V, service from 200 amps to 4,000+ amps
Why it matters: Three-phase power is more efficient for large motors, HVAC equipment, and commercial kitchen appliances. It requires different wiring, panels, and breakers.

Code and Inspection Requirements

Commercial inspections are more frequent and more rigorous than residential inspections
Wisconsin requires commercial electrical work be performed by licensed electricians (no homeowner permits for commercial)
Fire code, ADA compliance, and occupancy requirements add layers of electrical regulation
Emergency lighting and exit sign requirements apply to all commercial spaces
Some municipalities require periodic electrical inspections for commercial buildings

Wiring Methods

Residential: Primarily NM-B (Romex) cable through wood framing
Commercial: EMT conduit, rigid conduit, MC cable, or other approved commercial wiring methods. NM-B cable is not permitted in most commercial applications.
Why conduit matters: Conduit protects wiring in commercial environments, allows for easier future modifications, and meets fire code requirements for commercial occupancy types

Common Commercial Electrical Needs

New Business Buildout

Starting a new business in a commercial space typically requires:

Electrical load calculation: Determining the total power requirement for your specific business type
Panel and service sizing: Ensuring adequate power for all equipment, HVAC, lighting, and future growth
Lighting design: Meeting code requirements for illumination levels by occupancy type while managing energy costs
Circuit layout: Dedicated circuits for commercial equipment, POS systems, IT infrastructure, and specialized equipment
Emergency systems: Emergency lighting, exit signs, fire alarm connections, and emergency generator connections if applicable
Code compliance: ADA-compliant outlet heights, proper restroom electrical, and occupancy-specific requirements

Restaurant and Food Service

The most electrically intensive commercial spaces:

Commercial kitchen circuits: Ovens, fryers, walk-in coolers, hood systems, and dishwashers each require dedicated high-amperage circuits
Three-phase requirements: Large commercial cooking equipment often requires three-phase power
Hood system connections: Exhaust hoods with fire suppression require specific electrical connections and interlocks
Refrigeration: Walk-in coolers and freezers need dedicated circuits with alarm connections
Health code: Adequate lighting levels in food preparation areas are health code requirements, not just electrical code

Office and Retail

IT infrastructure: Server closets, structured cabling, dedicated circuits for network equipment, and UPS-backed power
Workstation power: Adequate circuits and outlets for computers, monitors, and peripherals — floor boxes for open-plan offices
Display lighting: Track lighting, accent lighting, and signage circuits for retail spaces
POS systems: Dedicated circuits for point-of-sale terminals, card readers, and receipt printers
Security: Access control, camera systems, and alarm panel circuits

Industrial and Manufacturing

Motor circuits: Large three-phase motors for machinery, compressors, and HVAC
Variable frequency drives (VFDs): Motor speed controllers that require specific wiring and grounding
Power factor correction: Reducing reactive power to avoid utility penalties
Emergency shutdown systems: Safety circuits that kill power to machinery in emergency situations
Specialized grounding: Sensitive equipment may require isolated grounding systems

Emergency Commercial Electrical Service

Electrical failures in commercial settings have immediate financial impact:

Lost revenue: Every hour without power is lost business
Food safety: Restaurants and grocery stores face spoilage costs and health code violations
Data loss: Server and network outages can cause data loss and customer-facing downtime
Safety liability: Loss of lighting, fire alarm systems, or emergency exit signs creates immediate safety and liability concerns

When to Call for Emergency Service

Complete loss of power (when neighboring businesses have power)
Burning smell from any electrical component
Sparking or arcing at any location
Tripped main breaker that won't reset
Water intrusion into electrical panels or equipment
Any situation affecting life safety systems (fire alarm, emergency lighting, exit signs)

Energy Efficiency for Commercial Buildings

Electrical upgrades that reduce operating costs:

LED retrofit: Commercial LED lighting reduces lighting energy costs by 50-75% and qualifies for utility rebates in many Wisconsin municipalities
Lighting controls: Occupancy sensors, daylight harvesting, and scheduled dimming reduce waste
Motor efficiency: Replacing old motors with high-efficiency models and adding VFDs for variable-speed applications
Power monitoring: Submetering allows you to identify which systems consume the most energy
Demand management: Scheduling high-draw equipment to avoid demand charge peaks on your utility bill

Choosing a Commercial Electrician

Not all electricians do commercial work. Look for:

Commercial experience: Residential and commercial electrical are different specialties
Proper licensing: Wisconsin requires commercial electrical work be performed by or supervised by a licensed master electrician
Insurance: Commercial jobs require higher liability coverage than residential
Code knowledge: Your electrician should be current on NEC, Wisconsin SPS 316, fire codes, and ADA requirements
Project management: Commercial projects require coordination with other trades, inspectors, and your business schedule

Get a Commercial Electrical Assessment

Whether you're planning a buildout, renovation, or need ongoing commercial electrical support, start with a professional assessment. Call Couillard Electric at (262) 618-2851 for a free estimate.

Serving commercial properties in Sheboygan, Mequon, Port Washington, Grafton, Cedarburg, West Bend, Plymouth, Kohler, and surrounding Wisconsin communities.