The 10-point checklist
Each of these is a classic symptom of harmonics, voltage disturbances, unbalance or a poor power factor. Any one is worth investigating; several together strongly suggest a survey.
- Breakers or RCDs trip for no clear reasonHealthy circuits tripping intermittently often points to harmonics or transient events rather than a genuine fault.
- Lighting flickers or dimsVisible flicker, especially when large loads start, indicates voltage fluctuation or flicker severity above comfortable limits.
- Equipment resets or shuts down at randomDrives, controls and IT dropping out can be caused by voltage dips lasting a fraction of a second.
- Transformers, cables or neutrals run hotUnexpected heat — particularly on the neutral — is a hallmark of triplen harmonics.
- Your electricity bill has crept up unexplainedReactive-power charges and inflated kVA from a poor power factor quietly raise costs.
- UPS alarms or batteries fail earlyA distorted or unstable supply shortens UPS battery life and triggers input alarms.
- Motors are noisy, hot or short-livedVoltage unbalance and harmonics cause extra heating and vibration in motors.
- You're planning to add EV chargers or large plantNew non-linear loads can push distortion past G5/5 limits — best assessed before you connect.
- The supply feels "full" but the meter disagreesLow power factor consumes capacity in kVA that never shows as useful kW.
- You have embedded generation (solar, CHP, battery)G99 connections usually require a power quality study before the DNO will energise.
Ticked two or more? The pattern is worth measuring. A power quality survey settles it objectively — logging your supply against BS EN 50160 and ENA G5/5 and identifying exactly which loads and disturbances are behind the symptoms.
Turn the checklist into answers
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