Electricians and the Building Regulations

by Steve on November 8, 2009

As well as complying with Part P (Electrical) electricians must be aware that they are required to comply with other parts of the Building Regulations.  The Building Regulations are Statutory (Law) and therefore care should be taken to comply with all aspects.


The Scope of Part P of the Building Regulations (England and Wales)

The scope of Part P  is concerned specifically with the safety of fixed electrical installations in dwelling houses & flats including gardens & outhouses. 

Also in commercial businesses where common areas are shared with residential premises.


Persons responsible for work within the scope of Part P may also be responsible for ensuring compliance with other parts of the Building Regulations.


Other responsibilities

Those other regulations concerning electricians and aspects of an electrical installation could be:


Building Regs  Part A        


It is important that the structure or load bearing capacity of a building is not compromised by the drilling or cutting of holes when installing electrical cables or equipment.

Attention must be paid to the depth of chases and sizes of holes and notches in joists.

For more detail read the article Holes, Notches and Chases


Building Regs  Part B        

Fire Safety


The provision of Fire detection Systems.

All new dwelling houses should be provided with a fire detection & alarm system in accordance with BS5839-6 (Code of Practice for Design & Installation of Fire Detection and Alarm Systems in Dwellings) to at least Grade D LD3.


Also new extensions to existing buildings and typical additions such as loft conversions may require a minimum of mains voltage Grade D alarm system to be linked to separate areas and to each floor level of a dwelling.


Holes made in Walls and Ceilings

Walls and ceilings in a building may be designed to provide

fire resistance.  Penetrations in walls and ceilings made to accommodate mounting boxes or recessed lighting may compromise such a Fire Barrier.




Building Regs  Part C        

Site Preparation & Resistance to Moisture

Holes or penetrations made whilst carrying out electrical installation could compromise the integrity of barriers against contaminants or moisture.


Common problem situations could occur are from:

-Penetrating damp proofing membrane   or from

-Drilling holes in flush mounted gas meter boxes when installing equipotential bonding (which could allow escaping gas into a wall cavity)


Building Regs  Part E         

Resistance to the Passage of Sound

Electrical installations must not degrade a buildings resistance to the passage of sound.


The sealing of penetrations and spaces around fittings, cables, conduits or trunking may be required to maintain sound proofing integrity.



Building Regs  Part F         


Adequate ventilation and installation of the correct sizing and siting of extract fans.


Extractor fans are required in rooms where water vapour and pollutants are present to prevent them spreading to other parts of a building.

More information on Extract fans & ventilation .


Building Regs  Part L         

Conservation of Fuel & Power

This section covers the use of energy efficiency with regard to lighting and heating.

The regulations are likely to change frequently as the EU Directives strive to reduce carbon emissions and more energy efficient products become available.


Fixed internal lighting

Relevant to new buildings, extensions and rewires.


-1 x energy efficient light fitting per 25 sq mtrs  or

-1 x energy efficient light fitting per four fixed light fittings (25%)

whichever is greater.


Fixed external lighting

-External lighting must be automatically controlled to switch off in daylight and when not required and have a maximum lamp capacity of 150 watts   or

-be an energy efficient light fitting.



Electric Boilers serving wet central heating systems

and  Electric Heating (other than Boilers)


-Electric Warm Air Heating

-Electric Panel Heaters

-Electric Storage Heaters


The main requirements for these systems relate to Energy Efficiency and Controls.

Electricians should be aware that:

-Dwellings with a floor area below 150 sq mtrs should be divided into at least 2 zones with independent temperature control, one of which should be assigned to the living area   and

-Dwellings with a floor area above 150 sq mtrs should be as above but with separate timing and temperature controls.


Boiler Replacements:

-Gravity systems should be converted to fully pumped

-New controls should be installed unless they are already installed and operational.


The Domestic Heating Compliance Guide- Compliance with Approved Documents L1A (New Dwellings) and L1B (Existing Dwellibngs) can be downloaded from:



Thermal Insulation

Today’s more energy efficient buildings methods require high levels of thermal insulation.

Electricians must be aware that circuits designed to use cable installation methods  (for flat twin & earth) 100, 101 and 102 must not be totally enclosed in thermal insulation. 

One side of the cable must be in contact with a thermally conductive surface.

Installation methods 103 relates to cables which are not in contact with such a surface and are subject to a de-rating factor of 0.5.


It would be advisable to make the builders and other trades aware of these thermal design limitations and also that luminaries must not be covered unless suitable.



Building Regulations  Part M     

Access to and Use of Buildings


Reasonable provision should be made so that electrical accessories are easily accessible by people whose reach is limited.

This includes heights of switches & sockets and access to consumer units.


Part M applies to all new dwellings. 

Rewires do not need to comply, providing the building is made no worse.


Essential reading for Electricians:

Electrician’s Guide to the Building Regulations

Download Building Regs from Communities.gov.uk


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