UK law creates the duty but does not prescribe the method. The Electricity at Work Regulations 1989 require you to prevent danger from electrical systems, and BS 7671 governs the installation, but neither tells you how to calculate incident energy. That gap is the study's job, and it is why the assumptions behind a UK arc flash report matter more than the number it prints.
BS 7671 · IET Wiring Regulations · HSR25 · IEEE 1584 · IEC 60909
There is no British standard for arc flash calculation. What defends the assessment is the quality of the fault level data and the reasoning recorded alongside it.
Regulation 4(3) requires systems to be maintained to prevent danger, and Regulation 14 restricts live working. The study is the evidence that the risk was assessed and the controls chosen were suitable and sufficient.
Prospective fault current comes from the Distribution Network Operator for your licence area, of which there are fourteen in Great Britain. We request it in writing rather than assume it, because the figure drives every downstream calculation.
With no UK method prescribed, IEEE 1584-2018 is the convention in industrial settings. Because it is a convention rather than a requirement, the report records why the model was chosen and where its assumptions bound the result.
BS 7671:2018+A2:2022 sets the installation standard, including the Amendment 2 requirements for arc fault detection devices. It governs the system being assessed, not the assessment itself.
Establish who holds the EAWR 1989 duty for the installation, which parts are in scope, and where the DNO boundary sits.
Obtain prospective fault current and clearing characteristics in writing from the Distribution Network Operator for the licence area.
Verify the single line diagram, record equipment ratings and conductor routes, and capture protective device settings as found.
Short-circuit and coordination study, then incident energy to IEEE 1584-2018, with the method basis recorded in the report.
Labelling, PPE recommendations and a written assessment that supports the duty holder's position under EAWR 1989.
Because no British standard prescribes a method, a UK assessment is only as defensible as the data and reasoning behind it. These are the weaknesses that matter if the HSE asks to see the basis.
Not by name. The Electricity at Work Regulations 1989 require you to prevent danger from electrical systems, and the Management of Health and Safety at Work Regulations require a suitable and sufficient risk assessment. No British standard prescribes how to assess arc flash risk, so the study is the means of discharging a duty that does exist rather than a standard you are audited against.
BS 7671:2018+A2:2022, the IET Wiring Regulations, is an installation standard. It governs how the system is designed and installed, including the Amendment 2 requirements for arc fault detection devices, but it does not set out a method for calculating incident energy or selecting PPE. It describes the system being assessed, not the assessment.
From the Distribution Network Operator for your licence area. Great Britain has fourteen DNO areas, and the prospective fault current at your supply is theirs to confirm. We request it in writing because an assumed figure undermines every calculation that follows, and because a network reinforcement can change it without notice to the site.
IEEE 1584-2018 is the usual choice in industrial settings, and IEC 60909 or ENA Engineering Recommendation G74 are used for fault level work. Because no UK standard mandates a method, what matters is that the report states which was used and why it suits the installation, so the reasoning can be examined later.