EN 50160 is the European standard that describes the voltage a public distribution network should deliver at the customer’s supply terminals. Its full title is Voltage characteristics of electricity supplied by public distribution networks. It does not tell you how to build equipment, and it is not an emission limit for your plant. It tells you what “normal” supply looks like, so you can tell whether a problem is coming from the grid or from inside your own site.
This guide explains what the standard covers, how compliance is actually judged, the main low-voltage limits in plain words, and what it does not cover.
Which edition applies
The current edition is EN 50160:2022, which replaced the 2010 edition and its amendments. An amendment, A1:2025, followed; CENELEC describes it as a clarification without significant technical changes, but it makes the Table 8 harmonic values mandatory for high- and extra-high-voltage systems (BSI summary). National versions such as EVS-EN 50160 carry the same text. Always quote the edition when you report against it.
Outside Europe, EN 50160 is still widely used as a reference by utilities, consultants and equipment vendors in the Middle East, Africa and Asia, because it gives a clear, measurable definition of acceptable supply.
How compliance is judged: one week, 10-minute values, 95 %
The most important thing to understand about EN 50160 is that it is statistical. Most limits are not “never exceed”. They say that a characteristic must stay inside a band for a percentage of a measurement period:
- Measure for one week.
- Aggregate each parameter into 10-minute values (frequency uses 10-second values).
- Ignore intervals where the supply was interrupted or far outside its normal range, so that one fault does not distort the statistics.
- Count how many of the remaining 10-minute values are outside the limit.
- For most parameters, the supply complies if at least 95 % of the values are inside the limit.
That is why a single spike on a chart does not make a site “non-compliant”, and why a week of data is the minimum for a meaningful EN 50160 report. It is also why the measurement method matters: two instruments that aggregate differently can give different answers on the same supply.
The main low-voltage limits in plain words
The values below are the ones most often used for low-voltage networks. They are summarised from published application notes; check the standard itself before you use them in a contract or a compliance report.
| Characteristic | What EN 50160 expects (LV) | Assessed over |
|---|---|---|
| Supply voltage variation | 10-minute mean values within ±10 % of nominal for 95 % of the week | 1 week |
| Power frequency (interconnected systems) | 50 Hz ±1 % for 99.5 % of the year; +4 % / −6 % at all times | 1 year, 10-second values |
| Flicker | Long-term severity Plt ≤ 1 for 95 % of the week | 1 week |
| Voltage unbalance | Negative-sequence component ≤ 2 % for 95 % of the week (up to 3 % in some areas) | 1 week |
| Total harmonic distortion | THD ≤ 8 %, including harmonics up to the 40th, for 95 % of the week | 1 week |
| Individual harmonics | A limit per order (for example 6 % for the 5th) for 95 % of the week | 1 week |
| Voltage dips, interruptions, overvoltages | No hard limit; reported and classified by depth and duration | Typically 1 year |
Sources: ACT’L EN 50160 technical sheet, NI evaluation standards.
Want to check a harmonic spectrum you already have? Our THD calculator computes THD from individual harmonic values and compares it with the 8 % EN 50160 level and the IEEE 519 limits.
What EN 50160 does not do
- It does not set limits on voltage dips. Dips are the disturbance that stops most production lines, yet the standard only describes them and suggests how to classify them by depth and duration. To prove that sags are stopping your process, you need event records with waveforms, not a weekly compliance report.
- It does not limit what your plant injects. Harmonic currents from your drives and rectifiers are covered by other documents, such as IEEE 519 and the IEC 61000-3 series. Read our guide to harmonics and power factor for that side.
- It is not an equipment immunity standard. A supply that meets EN 50160 can still trip sensitive equipment. A 95 % rule allows 5 % of the week to be outside the limit, and that 5 % is often exactly when the trip happens.
- It describes the public supply terminals. Problems created inside the site, after the point of connection, are outside its scope.
How to run an EN 50160 check
- Choose the point. Measure at the point of common coupling, usually the main incomer, so that you are assessing what the utility delivers.
- Measure for at least one full week. Include a full production cycle and a weekend.
- Record events as well as statistics. Weekly percentages show whether the supply is generally compliant; event records with the waveform before and after show what happened during the moments that matter.
- Compare like with like. If you are discussing results with a utility, agree on the instrument class, the edition of the standard and the aggregation method first.
- Keep monitoring if the question is a rare event. A one-week campaign answers “is the supply generally within EN 50160?”. It does not answer “what happened during last month’s trip?” See portable vs permanent monitoring.
How Inspector helps
Inspector records the parameters EN 50160 is assessed on: RMS voltage, frequency, flicker (Pst and Plt), unbalance, THD and individual harmonics, plus dips, swells, interruptions and transients classified in line with IEC 61000-4-30. Each event is stored with 5 cycles before and after, so a weekly picture can be matched with the exact moments that caused a problem. A permanent Inspector V4 keeps that record running after the week is over.
To discuss how to set up an EN 50160 check on your site, book a call with an Inspector engineer or start with the free assessment.
