UK power quality obligations sit with your Distribution Network Operator, and there are fourteen of them across Great Britain. The connection agreement sets what you may inject at the point of common coupling, the ENA Engineering Recommendations set the planning levels behind it, and BS 7671 governs the installation on your side of the meter.
BS 7671 · IET Wiring Regulations · HSR25 · IEEE 1584 · IEC 60909
The limits are set by your DNO, not by a single national number, so the first job is establishing which apply to your connection.
Great Britain has fourteen DNO licence areas, and the conditions attached to your connection are the operative limits. We establish them in writing, because they differ between operators and connection voltages.
Engineering Recommendation P28 covers voltage fluctuation and flicker, and P29 sets planning levels for unbalance. They sit behind what the DNO will accept, and raw measurements without them cannot support a connection case.
The IEC 61000 series covers both what your equipment emits and what it must tolerate. On sites where the complaint is nuisance tripping rather than a DNO letter, immunity is usually the more relevant half.
BS 7671:2018+A2:2022 governs the installation itself, including the Amendment 2 requirements for arc fault detection devices. It describes the system being measured rather than setting the power quality limits applied to it.
Confirm whether this is a DNO connection matter or a plant reliability investigation, because the two need different measurement points and different evidence.
Request the applicable limits and the point of common coupling from the DNO for your licence area, in writing, rather than applying a generic figure.
Record at the agreed points for a window that covers the process conditions that matter, including the loads suspected of causing the disturbance.
Distinguish distortion generated on site from disturbance arriving on the supply, and identify dominant harmonic orders and any resonance.
Findings against the connection conditions, mitigation options with expected effect, and a basis the DNO can check.
A UK study is usually needed for one of two reasons: a DNO has raised a connection condition, or plant is tripping and nobody knows why. Those need different evidence, and studies scoped for one rarely answer the other.
Your Distribution Network Operator, through the conditions attached to your connection. Great Britain has fourteen DNO licence areas and the limits are not uniform between them or between connection voltages. The ENA Engineering Recommendations sit behind those conditions, with P28 covering voltage fluctuation and flicker and P29 setting planning levels for unbalance.
At the point of common coupling that your connection agreement refers to. Recording downstream of it is a common reason a study cannot be used in a DNO discussion, because the figures describe a different boundary from the one the limits apply at. We fix the point before any instrument is installed.
No, and conflating them wastes a survey. An emissions study asks what your site injects into the network and is judged against DNO conditions. A reliability investigation asks what your equipment is receiving and is judged against immunity, usually under the IEC 61000 series. They need different measurement points and often different recording windows.
BS 7671:2018+A2:2022, the IET Wiring Regulations, is an installation standard. It governs how the system on your side of the meter is designed and installed, including the Amendment 2 requirements for arc fault detection devices, but it does not set the harmonic, flicker or unbalance limits your connection is assessed against.