Commercial backup power: specialized experience matters.
Commercial backup power contractor selection significantly affects system reliability, sizing appropriateness, and operational integration.
By Steven Lockhart · Reviewed by Alex Towery, C-10 #989290
Updated 2026-06-16
Choosing a commercial backup power electrician: C-10 license (baseline), documented commercial backup power portfolio (50+ installations), brand training/certification for major generators (Generac, Kohler, Cummins), commercial ATS installation experience, comfortable with load study and sizing analysis, PG&E commercial coordination experience for installations affecting service. Match contractor capability to project complexity (small generator vs large commercial system require different experience levels).
01What distinguishes commercial backup expertise.
Sizing analysis distinguishes adequate from excellent. Right-sizing requires load study, growth projection, NEC continuous-duty calculation, equipment-specific consideration. Contractors with deep experience right-size confidently; less-experienced contractors often oversize 'just in case' (waste of money) or undersize (operational failure during outages).
Brand integration matters for installation and warranty. Generac, Kohler, Cummins all have factory training programs; certified installers handle brand-specific procedures correctly and maintain warranty. Brand mismatch between generator and ATS adds installation complexity and reduces communication. Brand-aligned installation simpler and better-supported.
02Three evaluation criteria.
Generator and ATS portfolio
50+ installations in past 5 years is meaningful experience. Mix of small commercial (residential-style) and larger commercial systems. Specific brand experience (Generac, Kohler, Cummins) relevant to your project.
Sizing analysis approach
Quality contractors do load study before sizing recommendation. Ask about sizing methodology — should include essential loads identification, peak demand calculation, NEC derating, growth margin. Vague sizing approach indicates weaker analysis.
Commissioning practice
Full commissioning includes no-load testing, load transfer testing, exercise schedule verification, documentation. Skipping commissioning steps leaves issues undetected. Ask about commissioning protocol.
03What we offer at Towery for commercial backup.
120+ commercial backup power projects across Marin since 2020 including small business essential loads systems, restaurant and medical office full operational continuity systems, larger commercial whole-business backup. Generac, Kohler, and Cummins certified installations. PG&E commercial coordination experience. Standardized sizing analysis with load study, growth projection, right-sized generator selection.
Standard scope includes: load study, sizing analysis, generator selection consultation, ATS selection and installation, essential loads sub-panel where appropriate, commissioning with load transfer testing, documentation including operating instructions for business operations. 1-year installation warranty plus generator manufacturer warranty (typically 2-5 years parts, varies by brand and model).
Common questions.
How do I evaluate backup power contractors?
Verify C-10 license, request documented portfolio (50+ installations), check references from commercial customers, evaluate sizing analysis methodology, verify brand certifications, request commissioning approach details. Quality contractors welcome detailed evaluation.
Should I get multiple quotes?
Yes for commercial backup projects above $10,000. Same-scope quotes from qualified contractors typically within 15-25% of each other. Larger variances signal different sizing assumptions, different equipment quality, or different scope assumptions. Verify scope alignment before comparing prices.
What questions should I ask?
Specific: How many commercial backup systems past 5 years? What sizing methodology do you use? Brand certifications? Commissioning protocol? Documentation included? Permits and PG&E coordination? Warranty terms? Quality answers correlate with successful projects.
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.