Three-phase power: for serious loads.
Three-phase service enables efficient operation of large motors, industrial equipment, and commercial HVAC. Adding three-phase where it doesn't exist is a coordinated PG&E + electrical project.
By Steven Lockhart · Reviewed by Alex Towery, C-10 #989290
Updated 2026-06-16
Three-phase service install/upgrade scope: PG&E service request and coordination (4-12 weeks typical), service entrance equipment (meter, main switchgear), wire from utility transformer to building, main distribution panel three-phase rated, branch panels and feeders to loads. Total Marin project cost varies enormously: $15,000-$60,000+ depending on whether transformer is already on site, distance from transformer to building, service size, and switchgear scope.
01Why three-phase matters.
Three-phase electrical service provides balanced power across three current-carrying conductors with phases 120 degrees apart. This enables three-phase motors (more efficient, smaller, longer-lasting than single-phase equivalents at the same HP), supports much larger total loads on the same conductor sizes, and provides more stable power for sensitive industrial electronics. Commercial buildings and industrial facilities almost universally use three-phase service; single-phase is rare beyond residential and small commercial.
In Marin, three-phase service is widely available in commercial corridors (Northgate, Bel Marin Keys, Hamilton, downtown San Rafael, Larkspur Landing, Sausalito harbor) but limited in residential neighborhoods and some smaller commercial zones. Adding three-phase service to a property that doesn't have it requires PG&E to extend three-phase distribution to the property — sometimes a modest project (existing three-phase lines on the street), sometimes major project (no nearby three-phase distribution, requiring line extension).
02Project scope.
PG&E coordination
Service request, load study submission, sometimes engineering review for line extension, scheduling of transformer install or upgrade, utility-side install. PG&E timeline 4-12 weeks typical.
Service entrance
Three-phase meter (typically 200A, 400A, 600A, or larger), main switchgear, sometimes CT cabinet for higher amperages. Modern installs use Square D, Eaton, or Siemens commercial-grade switchgear.
Distribution
Main distribution panel (MDP) three-phase rated, sub-panels for branch loads, conduit and feeders between panels. Larger installations use sectionalized switchgear with multiple distribution sections.
03Marin install timelines and costs.
Where three-phase is already available at the property (transformer nearby, just needs service entrance): $15,000-$35,000 for typical small commercial install (200-400A). 4-8 weeks total timeline including PG&E. Where line extension is required (transformer must be added or extended distribution lines installed): $40,000-$150,000+, 12-24 weeks timeline. Site survey and PG&E preliminary review determine which category your project falls into.
Industrial-scale installations (600A+, complex switchgear, primary metering) scale up further. Commercial buildings in light industrial zones (Hamilton, North San Rafael, parts of Novato) typically have adequate existing three-phase distribution; rural Marin (parts of West Marin, Lucas Valley, some Lagunitas areas) sometimes requires significant PG&E line extension to access three-phase.
Common questions.
How do I know if three-phase is available at my address?
PG&E can perform a preliminary review based on address. Visual indicators: three-wire-plus-neutral distribution on poles indicates three-phase available nearby; two-wire-plus-neutral distribution indicates single-phase only. We can perform a site survey and submit a preliminary inquiry to PG&E during the planning phase, getting a feasibility and rough timeline before committing to engineering and permit pull.
Can I use a phase converter instead of true three-phase?
Phase converters (rotary or VFD-based) generate three-phase from single-phase input. Useful for occasional or small three-phase loads (small machinery, occasional commercial equipment) but inefficient and expensive for sustained or large loads. For meaningful commercial/industrial operation, true three-phase service from PG&E is the right answer despite higher install cost.
What if I'm leasing the space?
Three-phase service additions are typically landlord investments because they're property infrastructure improvements that persist beyond a single tenant. Tenants seeking three-phase typically work with landlord (lease negotiation, sometimes shared cost) or factor service cost into lease term. We work with both tenants and landlords on three-phase projects; landlord involvement is usually necessary for permit pull.
Will three-phase upgrade interrupt existing operations?
Yes, partially. The transition from single-phase to three-phase service requires PG&E to disconnect existing service, install new equipment, then reconnect new service. Outage duration 1-4 hours typical for the cutover day. We schedule cutover for low-impact time (early morning, weekend) and coordinate with PG&E for narrow outage windows. All work other than the cutover can occur in parallel with existing operations.
How do you handle pricing — flat fee or hourly?
Both, depending on scope. Routine service calls and predictable scope (panel replacement, EV charger install, transfer switch install, fixture replacement) are flat-fee quoted up front. Diagnostic visits and emergency scope are hourly because we don't know what we'll find. Either way, you get a written quote before work starts on anything significant, and we don't proceed beyond the quote without your sign-off.
How quickly can you schedule?
Depends on scope and season. Emergency dispatch: same-day across Marin County (1-3 hours business hours, 1-4 hours after-hours). Same-day standard service: 3-6 hours from call when capacity allows; otherwise next business day. Scheduled service work: 1-3 weeks typical. Larger projects requiring permits and PG&E coordination: 4-12 weeks depending on scope. We're upfront about timeline at the quote stage.
What warranty do you offer on work?
Our standard residential warranty: 2 years on labor, manufacturer warranty on parts (varies by product — typically 1-10 years). Major installs (panels, generators, EV chargers) often have longer manufacturer warranties (5-10 years). If there's an issue with our work in the warranty period, we come back and fix it at no cost. We also stand behind work past warranty — repeat customers and referrals matter more than a transactional fix.
Are you licensed and insured?
Yes. California State License Board C-10 Electrical Contractor #989290, in good standing. Carry general liability insurance and workers' compensation insurance as required by California law. Bondable on projects requiring it. Happy to provide proof of insurance to clients or property managers on request. License lookup: cslb.ca.gov.
Talk to a licensed electrician in Marin.
Family-run, C-10 #989290, 20+ years in the trade. Honest scoping, fair pricing, work that lasts.