Power quality issues: invisible until they damage equipment.
Voltage sags, harmonics, transients, and frequency variations can damage sensitive equipment and disrupt operations. Power quality monitoring identifies issues before they cause failures.
By Steven Lockhart · Reviewed by Alex Towery, C-10 #989290
Updated 2026-06-16
Power quality issues include: voltage sags (brief reductions causing equipment resets), voltage swells (brief increases stressing electronics), harmonics (distorted waveforms from non-linear loads, heating transformers and neutrals), transients (fast spikes, often surge-related), frequency variations (rare but damaging when present). Monitoring uses power quality analyzers (Fluke 1750/1770 class) deployed at strategic points, recording events over 1-4 week windows. Commercial application: troubleshoot specific issues or document infrastructure quality before adding sensitive equipment.
01What power quality monitoring identifies.
Voltage sags are the most common commercial power quality issue. PG&E grid disturbances, lightning, fault clearing events, and motor starting all cause sags. Sensitive electronics (servers, medical equipment, industrial controls) sometimes restart or fault during sags. Monitoring identifies sag frequency, depth, and source — informing decisions about UPS sizing, power conditioner deployment, or grid service upgrades. Modern Marin commercial often experiences 5-15 sags per month, most brief enough that occupants don't notice but sometimes impacting specific equipment.
Harmonics build up in installations with significant non-linear loads (variable-frequency drives, LED lighting at scale, computer equipment). Harmonic currents flow in neutrals and can overheat neutral conductors (designed for fundamental-frequency current). 3rd, 5th, 7th, 9th harmonics typically dominant. Significant harmonic distortion (>5% THD typically) warrants attention — sometimes requires harmonic filters, sometimes K-rated transformers, often just awareness and conductor sizing in design. Monitoring quantifies the issue.
02Three monitoring scenarios.
Troubleshoot specific equipment issues
When specific equipment is faulting or behaving anomalously, power quality monitoring identifies whether grid quality is contributing. 1-2 week monitoring at affected equipment location identifies sag, transient, or harmonic patterns. $1,200-$2,500 for monitoring service plus analysis.
Pre-install survey for sensitive equipment
Before installing sensitive equipment (servers, medical, scientific), monitor existing power quality to identify any issues warranting mitigation before equipment install. $800-$1,800 for typical pre-install survey.
Ongoing monitoring for critical operations
Some critical operations install permanent power quality monitors (Power Logic, Eaton PowerXpert) providing continuous monitoring. Higher capital cost ($3,000-$10,000+ for monitoring equipment) but ongoing visibility without recurring service costs.
03Marin commercial typical scope.
Standard monitoring scope: Fluke 1770 or equivalent power quality analyzer deployed at affected location, current and voltage probes installed on monitored circuits, 1-4 week monitoring duration depending on issue patterns and operational schedule, comprehensive analysis after monitoring completes, written report with specific findings and recommendations. Common findings in Marin commercial: occasional voltage sags from PG&E grid events, modest harmonic distortion from typical office equipment, transient events from local switching or surge events.
Recommendations after monitoring vary by findings. Voltage sag impact: UPS for affected equipment, power conditioner, or service upgrade if sag root cause is on-site. Harmonic distortion: harmonic filter, K-rated transformer, or design accommodation. Transients: improved surge protection (whole-house and point-of-use SPD). Most Marin commercial monitoring finds modest issues addressable with targeted mitigation; severe issues are rare but identifiable.
Common questions.
How do I know if I have power quality issues?
Symptoms suggesting power quality: equipment randomly resetting or faulting (especially during specific times like motor starting), shorter-than-expected battery/UPS life, overheating transformers or neutrals, unexplained equipment failures. If symptoms suggest grid quality, monitoring confirms or rules out. If no symptoms, monitoring isn't generally necessary unless adding sensitive equipment.
What's typical power quality in Marin?
PG&E service in Marin is generally clean by US standards but not perfect. Typical residential and small commercial: 5-15 brief voltage sags per month (mostly undetected by occupants), modest harmonics from office equipment (well within tolerance), occasional transients from PG&E switching or weather events. Commercial spaces with significant motor loads or non-linear loads may have more variability. Mostly fine for typical equipment; occasionally problematic for sensitive specific equipment.
What does monitoring cost?
Service-based monitoring: $1,200-$2,500 for typical 1-2 week monitoring engagement including analysis and report. Capital monitoring: $3,000-$10,000+ for permanent monitoring equipment installation. Service approach works for occasional troubleshooting; capital approach better for ongoing critical operations where continuous monitoring informs operational decisions.
Can power quality issues damage my equipment?
Yes — sustained issues can. Voltage sags cause progressive component stress in electronics; over time, capacitors and power supplies degrade faster. Harmonics overheat transformers and neutrals, sometimes leading to insulation failure. Transients damage sensitive electronics directly. Most healthy commercial environments don't have damaging power quality, but specific facilities with documented issues benefit from mitigation.
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.