Power quality troubleshooting checklist

Power-quality troubleshooting improves when symptoms are tied to time, equipment, measured values, and facility events instead of vague complaints.

Use this guide to organize symptoms, timestamps, measurements, utility versus facility clues, and escalation evidence before selecting mitigation.

When to use this guide

• A facility sees flicker, nuisance trips, motor overheating, equipment alarms, dimming, resets, sag/swell complaints, or unexplained failures.
• The utility asks for timestamps, affected loads, measurements, account information, and event context.
• The issue may be related to motor starting, voltage imbalance, harmonics, transients, load balance, or facility wiring.

Inputs to gather

• Symptom log with timestamp, duration, weather, outage context, affected loads, unaffected loads, and operator notes.
• Facility events: motor starts, VFDs, welders, EVSE, HVAC, capacitor switching, generator transfer, process events, or tenant loads.
• Measurements: voltage, current, imbalance, load by phase, event recorder data, photos, meter logs, and single-line context.
• Utility account, service voltage, transformer context where known, equipment lists, maintenance history, and prior complaints.

Project path matrix

Working checklist

• Confirm the project branch: A facility sees flicker, nuisance trips, motor overheating, equipment alarms, dimming, resets, sag/swell complaints, or unexplained failures.
• Measure or photograph the first hard inputs: Symptom log with timestamp, duration, weather, outage context, affected loads, unaffected loads, and operator notes. Facility events: motor starts, VFDs, welders, EVSE, HVAC, capacitor switching, generator transfer, process events, or tenant loads.
• Record the decision basis: One voltage reading is rarely enough to diagnose a power-quality problem. Utility processes and customer responsibility boundaries vary by service territory.
• Keep the handoff package together: Symptom/event log, affected-load list, unaffected-load list, photos, and operator notes.
• Stop before work proceeds if this applies: The symptoms affect life-safety, medical, process, refrigeration, data, or production-critical equipment.

Workflow

1. Create an event log before guessing the cause.
2. Classify symptoms as possible sag, swell, flicker, imbalance, harmonics, transient, nuisance trip, heat, noise, or equipment alarm.
3. Correlate events with facility loads and utility/outage records.
4. Collect measurements over a useful duration and at relevant points in the system.
5. Send a clear packet to the utility, engineer, electrician, or power-quality specialist before buying mitigation.

Decision checkpoints

• One voltage reading is rarely enough to diagnose a power-quality problem.
• Customer equipment and utility-side events can produce similar symptoms.
• Mitigation should match measured cause, not just the loudest symptom.
• Voltage imbalance, loose connections, motor-starting dips, and harmonics need different checks.

Canada-specific checks

• Utility processes and customer responsibility boundaries vary by service territory.
• Use qualified measurement methods and local utility escalation procedures.
• This guide does not diagnose final cause or approve mitigation.

Project package to keep

• Symptom/event log, affected-load list, unaffected-load list, photos, and operator notes.
• Voltage/current measurements, imbalance or load-balance outputs, event recorder files where available, and single-line context.
• Utility account information, service context, equipment data, and escalation correspondence.

Stop and get local review

• The symptoms affect life-safety, medical, process, refrigeration, data, or production-critical equipment.
• Measurements indicate severe imbalance, overheating, nuisance tripping, or repeated equipment damage.
• Mitigation is being proposed without measurements or event correlation.

Questions to settle before work starts

• Which local authority, utility, property authority, product listing, or manufacturer instruction controls this power quality decision?
• Which inputs are measured from the field or nameplate, and which are still assumptions from a quote, drawing, or memory?
• Which part of the work will be concealed, energized, interconnected, or purchased before review if the sequence is not controlled?
• Which single assumption would change the equipment choice, installation path, cost, schedule, or inspection timing?
• Who will keep the final photos, calculator outputs, product documents, permit or utility records, and commissioning notes?

Use the related tools

• Use the Voltage Imbalance Calculator when phase voltage readings are available.
• Use the Three-Phase Load Balance Calculator when load assignment may be part of the issue.
• Use the Motor Starting Voltage Dip Calculator when symptoms correlate with motor starts.

Public reference starting points

• BC Hydro power quality reference guide - Utility power-quality context.
• Hydro One power quality - Utility escalation context.

Local standards and authority note

Confirm measurement methods, utility responsibilities, and mitigation choices with the utility and qualified power-quality professionals.