What Is Clean Power?

In a balanced three-phase network, voltage and current magnitudes should be equal across all phases, with each phase shifted symmetrically by 120 degrees. When this balance is disrupted, appliances suffer. Voltage and current unbalance can affect hundreds of customers—even from a single substation—and in severe cases, entire provinces.

Global Standards vs Local Reality

In the United States, voltage variation is limited to ±5%. In most European countries, it’s ±10%. South Africa’s standards? Eskom’s Quality of Supply document discusses the consequences of unbalanced voltages, but doesn’t clearly define acceptable voltage variation limits.

Harmonics, Flicker & THD

NRS 097-2-1:2017 (Grid Interconnection of Embedded Generation) references Total Harmonic Distortion (THD) and flicker, citing IEC-61000-3. IEEE standards 519 and 1547 also specify acceptable harmonic levels. THDu (voltage distortion) should not exceed 8%.

But who enforces this? In Gauteng, I recently encountered a case where THD far exceeded the 8% threshold. And if it’s happening there, it’s likely happening elsewhere—on feeders and substations across the country.

Who’s Responsible?

Utility companies are tasked with monitoring and maintaining power quality. But in practice, this is rarely done. Effective monitoring requires more than equipment—it demands skilled professionals who know where to look, how to interpret data, and most importantly, how to act quickly.

“Power quality issues are not just technical—they’re economic, operational, and deeply personal. They affect every home, every business, and every bottom line.”