Introduction to "Part P"

There is a lot of confusion and misinformation around the web about so called "Part P".  It's a subject that  anyone wanting to do D.I.Y. home automation should be aware of, so I thought I would shine some light on it.  I'll reference the actual legal documents so that you can verify the information I'm giving.


The Source Documents

The legal documents surrounding building regulations consists of several layers.  They bottom layer is the most general, but it is also the most legally binding.  The later layers become more detailed, but they rely on the lower layers to give them power.  The last couple of layers are merely recommendations.

Layer 1: Building Act 1984

This is an act of parliament, and as such has real legal clout behind it.  However, it is very vague.  The important bit is:

The Secretary of State may... make regulations with respect to the design and construction of buildings and the provision of services, fittings and equipment in or in connection with buildings.

Regulations made... above are known as building regulations.

The full text can be found here: Building Act 1984

This act allows the secretary of state to make "Building Regulations", which can be changed from time to time.

Layer 2: The Building Regulations 2010

The latest revision of the building regulations was made in 2010.  Technically this is a form of secondary legislation known as a statutory instrument.  It still has strong legal standing, but is more readily changed than an act of parliament, which is primary legislation.

The full text of The Building Regulations 2010 is quite long and complex.  I'll try to summarise the salient points though.

Any work done to buildings must be done so that it is safe.  In other words, buildings shouldn't fall down, burn too easily, etc.  They should also be reasonably energy efficient, and provide suitable levels of comfort to the people using them.  It is the duty of your Local Authority Building Control (L.A.B.C.) office to ensure this.

The normal method is for a builder to submit plans to the L.A.B.C. for them to approve.  They then also inspect the work at various stages, before signing it of as complete and complying with the building regulations.  They L.A.B.C. charge for all of this, and if they have to get a "consultant" in, then you will be paying for it. "Consultant" could include an electrician to test some electrical work you have done.

There are exceptions where certain types of work can be carried out by certain people who are allowed to sign the work off themselves.  However they still need to give notice to the L.A.B.C. that the work has happened.  Electrical work is one type of work where an exemption exists.  However they only people who are allowed to sign off there own electrical work are those registered with one of the self certification schemes.

There are also thankfully some types of work which don't require notification, and these can be carried out by anyone who is capable of doing them safely and to a suitable standard.  The work should still be done according to the guidance of the "Approved Documents".  The types of work that are exempt from notification can be found in Schedule 4.  The electrical ones are mixed in with some non-electrical ones, which can make it a confusing read.  More on this in Layer 3.

Layer 2½: Schedule 1 of the Building Regulations 2010

This is split into numerous parts, each denoted by a letter.  The part relating to electrical safety is Part P and is in fact very simple:

Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury. 

The requirements of this part apply only to electrical installations that are intended to operate at low or extra-low voltage* and are:

(a) in or attached to a dwelling;

(b) in the common parts of a building serving one or more dwellings, but excluding power supplies to lifts;

(c) in a building that receives its electricity from a source located within or shared with a dwelling; and

(d) in a garden or in or on land associated with a building where the electricity is from a source located within or shared with a dwelling.

*In case you are wondering "Low voltage" can be up to 1000V!

So you may be wondering why all the confusion about "Part P"?  Well there is a bit more to Part P than this, which we will come to in Layer 3.  Also, Part P is not the only part of the building regulations that affect electrical work.  Parts A, B, C, E, F, L and M are also relevant.

Layer 3: Approved Documents

The Approved Documents are where the real detail is kept, but they are not legally binding.

Approved Documents are intended to provide guidance for some of the more common building situations. However, there may well be alternative ways of achieving compliance with the requirements. Thus there is no obligation to adopt any particular solution contained in an Approved Document if you prefer to meet the relevant requirement in some other way.

However, if you were unfortunate enough to find yourself in court and you had not followed the approved documents advice, then it could be very difficult to show that you had complied with the building regulations.  You would be wise to follow the approved documents, unless you have a very unusual situation, in which case you would be wise to get an expert in.

There are several approved documents, one for each of the parts of schedule one of the building regulations.  The one relating to electrical safety is Approved Document P. At the time of writing the latest version was issued in 2006 and was due to be updated.

The core of Approved Document P is the following statement:

In the Secretary of State’s view, the requirements will be met by adherence to the ‘Fundamental Principles’ for achieving safety given in BS 7671:2001 Chapter 13.

BS7671 is better known as "The IEE Wiring Regulations".  The latest version is the 17th Edition or BS7671:2008.  This is the main reason that Approved Document P is due to be updated.  This is the one document which cannot be freely downloaded.  A printed copy will set you back about £60.  A cheaper alternative is The IEE On Site Guide, which is also mentioned in Approved Document P.

Tables 1 and 2 on page 8 give guidance on what work is not notifiable.  This is a repeat of the information in Schedule 4 but is somewhat easier to read.

Layer 4: Documents Referenced by The Approved Documents

As we have seen, Approved document P refers to BS7671 as a suggested means of complying with the regulations.  Approved Document L also refers to another document, The Domestic Building Services Compliance Guide 2010.  This makes recommendations about such things as the number of energy saving lights.


One important point to note is that complying with BS7671 requires amongst other things, for the electrical work to be tested appropriately.  The equipment to do this costs around £600 new.  A multimeter is not suitable.