Commercial load study, done right.
A proper commercial load study identifies actual peak demand, projected future loads, and the correct service size — preventing both undersized service (insufficient capacity) and oversized service (unnecessary cost).
By Steven Lockhart · Reviewed by Alex Towery, C-10 #989290
Updated 2026-06-16
Commercial load study process: install monitoring equipment for 2-4 weeks measuring actual load patterns, analyze peak demand and load curve, review nameplate ratings on connected equipment, identify near-term equipment additions (5-year planning horizon), apply NEC continuous-duty derating, recommend service size. Typical Marin load study scope: 1-3 weeks elapsed time, $1,500-$3,500 for thorough study. For most commercial upgrades, load study is required for accurate sizing and PG&E coordination.
01Why nameplate alone isn't enough.
Equipment nameplates show full-rated current — what each piece of equipment draws at maximum capacity. Real operations rarely run every piece of equipment at maximum simultaneously. The actual peak demand for a typical commercial building is often 30-50% of nameplate sum. Sizing service to nameplate sum produces oversized (and overpriced) service; sizing to historical demand without analysis can produce undersized service that fails when load grows.
Load study captures actual operational patterns: when peaks occur (typical Marin commercial peaks are HVAC + lighting + equipment startup around 9am, lunchtime kitchen surge for restaurants, etc.), what diversity factors apply, what equipment runs simultaneously vs sequentially. NEC's demand calculations (Section 220) provide standardized derating; load study provides actual data. Both inform sizing decisions.
02What the load study actually measures.
Real-time load monitoring
Current transformers and data loggers installed at main panel for 2-4 weeks, sampling load every 5-15 minutes. Captures real operational patterns: weekday vs weekend, business hours vs off-hours, seasonal variations. Provides actual peak demand data and load curve.
Nameplate inventory
Walk-through of building identifying connected loads: HVAC units (tonnage, voltage, amperage), commercial kitchen equipment, lighting circuits and wattages, dedicated equipment circuits, motor loads. Cross-references with main panel breaker labels to identify any unlabeled or undocumented circuits.
Future load projection
Discussion with business operations on near-term plans: new equipment, expansion, electrification, EV charging at the property, etc. Adds projected loads to sizing analysis with appropriate certainty discount.
03How load study findings drive sizing.
Final sizing combines three inputs: measured peak demand (load study data), NEC required calculations (Section 220 demand factors applied to nameplate), and projected future loads (5-year horizon with discount for uncertainty). Recommended service size typically: max(measured peak × 1.25, NEC calc, projected future load) rounded to standard PG&E service size (400A, 600A, 800A, 1200A residential-style; commercial-rated services step up from there).
We deliver load study report with measured data, calculations, projected loads, and recommended service size. The report becomes part of the PG&E service request documentation and AHJ permit application. Some Marin AHJs require load study documentation for service upgrades above specific thresholds; smaller scopes accept calculated sizing without monitoring.
Common questions.
How long does load study take?
Field monitoring: 2-4 weeks of data collection during normal operations. Analysis and reporting: 1 week after monitoring completes. Total study time 3-5 weeks. For projects with tight timelines, we can sometimes accelerate with shorter monitoring periods (1-2 weeks) but accuracy degrades. Most Marin commercial upgrade projects can accommodate full study within total project timeline since PG&E coordination is also weeks-long.
How much does load study cost?
Typical Marin commercial load study: $1,500-$3,500 depending on building size, complexity, and number of monitoring points. Cost included or separate from service upgrade quote depending on project scope. For smaller upgrades (under 400A), calculated sizing without monitoring sometimes acceptable to AHJ at lower cost. Larger upgrades typically warrant full monitoring study.
Can you size without load study?
For some scopes, yes — NEC calculations from nameplate inventory provide compliant sizing without monitoring. Accuracy is lower (calculations typically conservative, resulting in oversized service) but compliant. For projects where modest oversizing is acceptable and timeline doesn't allow study, calculation-only sizing works. We discuss approach during quote based on project specifics.
What if load study shows existing service is adequate?
Occasional finding — sometimes business growth assumptions overstate actual demand. If load study shows existing service handles current and projected loads, we recommend cancelling or deferring the upgrade. Cost of load study ($1,500-$3,500) is favorable insurance against an unnecessary $30,000-$80,000 upgrade. Honest finding even when it means not doing the project.
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.