ProjectCalcThe citation
Approved Document P (2013 edition) states its position at paragraph 1.1: "Electrical installations should be designed and installed in accordance with BS 7671:2008 incorporating Amendment No 1:2011" — the IET Wiring Regulations. Paragraph 1.7 repeats the point for new work: any new work should be carried out in accordance with BS 7671, and the existing electrical installation is considered too.
That is the whole architecture of Part P in one line. The building regulation is short and about safety and notification; the technical rules for how an installation is actually designed, selected, erected, inspected and tested are in BS 7671.
What the approved document expects to exist at the end
Paragraph 1.1 requires that the information provided for the installation should comprise the items listed in BS 7671, and gives examples of what that means in practice:
- electrical installation certificates or reports describing the installation and giving details of the installation and its constituents; and
- information on the equipment used, such as consumer units and residual current devices (RCDs).
So the paperwork is part of the job, not an afterthought. The certificate is what demonstrates the installation complies, and Part P's notification regime — a building notice, or self-certification by a registered competent person — is built around producing it.
How it fits with the notification rules
The notifiable list is in regulation 12(6A) and is reproduced at paragraph 2.5 of Approved Document P: the installation of a new circuit, the replacement of a consumer unit, or any addition or alteration to existing circuits in a special location. Everything else in a dwelling is not notifiable. Our Approved Document P page sets out the list and the definition of a special location around a bath or shower, with the measurements.
The distinction worth holding on to is that BS 7671 applies to the work whether or not it is notifiable. Not-notifiable does not mean not-regulated: it means the local authority does not have to be told, and the document expects non-notifiable work to be inspected and tested as well.
A note on editions
BS 7671 is amended on a cycle, and Approved Document P names the edition it was written against — BS 7671:2008 incorporating Amendment No 1:2011. That edition is now Withdrawn, as is BS 7671:2008+A3:2015. BSI catalogues BS 7671:2018+A4:2026 as the current edition (checked 22 September 2026), so the version named in the approved document is several amendments behind the Wiring Regulations as they stand. What does not change is that the installation has to comply with the edition in force when the work is carried out, and that a competent person works to the current edition.
What this means for a materials calculation
- A materials calculator cannot size a cable. Cable size depends on load, protective device, installation method, grouping and voltage drop — all BS 7671 calculations, none of which our tools attempt.
- Route and depth are not your choice alone. Chasing a wall for a cable, or running a supply to a garden building, changes the installation method and therefore the design.
- Consumer unit replacement is notifiable and is not a DIY job in the sense most people mean — it is one of the three things the regulation singles out.
- Get the certificate. If the work is done by a registered competent person, the certificate is the evidence that Part P and BS 7671 have been met.
Edition status — what the approved document cites, and what is current
An approved document names the edition of a standard that existed when it was written. That edition is not necessarily the current one. The table below sets out, for every standard this page relies on, the title as published, the edition the approved document cites, and the edition BSI catalogues today (22 September 2026). Where the cited edition is withdrawn, the page says so; where we could not confirm the replacement, no current edition is stated.
| Standard | Title as published | Edition cited by the approved document | Current edition (BSI) |
|---|---|---|---|
| BS 7671 | Requirements for Electrical Installations. IET Wiring Regulations | BS 7671:2008 incorporating Amendment No 1:2011 — cited by Approved Document P | BS 7671:2018+A4:2026 — Current (15 April 2026) |
Source: BSI catalogue records read at knowledge.bsigroup.com on 22 September 2026. Each title, designation, status and date in the last two columns was read from the BSI catalogue page for that standard.
Last verified 22 September 2026. Every requirement quoted on this page was read from the primary source listed below on that date, not from a summary. If a figure could not be confirmed in the primary source it is not on this page.
Where these figures come from
- Approved Document P: Electrical safety, 2013 edition — paragraphs 1.1, 1.7 and 2.5, citing BS 7671:2008 incorporating Amendment No 1:2011 — GOV.UK publications, "Electrical safety: Approved Document P", checked 22 September 2026.
- BSI catalogue (“BSI Knowledge”) — product record for each standard listed above: title, current edition and status — knowledge.bsigroup.com, checked 22 September 2026.
Guidance only, not advice
This page is a plain-English summary of published regulations and standards, written to help you plan a job. It is not professional advice, it is not a substitute for the actual document, and it is not a building-control decision.
Building regulations are enforced by your local authority (or an approved inspector) and the facts of a particular job can change the answer. Confirm with your local building control before you start work, and where a job is structural, get it designed by a suitably qualified person. If this page and the source document disagree, the source document wins.