400-Amp Electrical Service in Chicago

400-amp service typically shows up in these contexts:

• Large single-family homes over 5,000 square feet with central AC, electric laundry, and electric cooking
• Kenwood and Hyde Park mansions with multiple HVAC zones and pool or spa equipment
• Luxury new construction with all-electric design: heat pumps, induction, EV charging, radiant heat
• Coach houses and ADUs where the main house runs close to 200 amps already
• Two-flats and three-flats where each unit needs its own 100- or 150-amp service
• Small commercial buildings — retail, small restaurants, light office
• Commercial kitchens with gas cooking but heavy refrigeration and HVAC loads
• Small warehouses or automotive repair shops with equipment plug loads
• Medical offices and clinics with imaging or sterilization equipment
• Automotive dealerships installing EV charging for sales inventory

If your [panel upgrade](/services/chicago/electrical-panel-upgrade-chicago) conversation keeps coming back to "we'll need more than 200 amps," it's worth looking seriously at 400-amp service before you commit.

One distinction worth drawing: 400 amps of single-phase service is not the same as three-phase service. Many large commercial buildings in Chicago are fed by three-phase 208V or 480V service — a completely different utility feed that supports three-phase motor loads. ComEd supplies either type depending on building class and load, and the two are not interchangeable.

For most residential 400-amp installations, single-phase 240V service is what we're working with. For commercial buildings with three-phase motors (large HVAC, elevators, industrial equipment), we coordinate with ComEd to provision three-phase service. If you're not sure which you need, our site walk-through will tell you. See our [commercial lighting installation](/services/chicago/commercial-lighting-installation-chicago), [retail store electrical](/services/chicago/retail-store-electrical-chicago), and [office electrical buildout](/services/chicago/office-electrical-buildout-chicago) pages for commercial context.

A full 400-amp installation involves:

• Load calculation (NEC Article 220) to confirm 400 amps is appropriate
• ComEd service application and coordination with their engineering group
• Proper meter socket — often a 400-amp ring-type meter socket
• Service entrance conductors sized for the full rating with proper conduit
• Main disconnect — either a 400-amp main breaker or two 200-amp mains in a 400/320 combination
• Distribution to subpanels with appropriately sized feeders
• Grounding electrode system sized for the service (typically two ground rods plus water pipe bond; commercial may require a building steel bond)
• Whole-building surge protection — highly recommended at this capacity
• Permit through the Chicago Department of Buildings
• Final inspection and ComEd release

400-amp installations usually take two to four days of on-site work. In commercial properties, we phase the installation around business hours to minimize disruption.

• Supervising Electrician License: Owner-held, with permit-pulling authority for both residential and commercial work
• Chicago Code Expertise: Conduit, bonding, and grounding rules for Chicago differ from the surrounding suburbs — we build to the city spec
• Commercial Project Management: We coordinate with general contractors, ComEd engineers, and building inspectors so the project runs on schedule
• Real Load Calculations: No guessing at capacity — we run the NEC calculation and right-size the service
• Transparent Pricing: Written estimates, itemized scope, per-project cost
• Warranty-Backed: All installations backed by our workmanship warranty

We serve property owners and commercial clients across Chicago. For large-home and mansion-scale projects, see our [Lincoln Park](/services/chicago/electrician-lincoln-park-chicago), [Hyde Park](/services/chicago/electrician-hyde-park-chicago), [Kenwood](/services/chicago/electrician-kenwood-chicago), [Beverly](/services/chicago/electrician-beverly-chicago), [West Loop](/services/chicago/electrician-west-loop-chicago), [Bucktown](/services/chicago/electrician-bucktown-chicago), and [Wicker Park](/services/chicago/electrician-wicker-park-chicago) pages.

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