Repairs: electrics and miscellaneous items

Electrical wiring in dwellings is controlled through the Building Regulations Approved Document P (AD P), the original edition of which came into effect in 2006. AD P provides the basic mechanism to bring electrical wiring work within the scope of the Building Regulations.

Guidance in the form of Codes of Practice published by the IET (formerly the Institution of Electrical Engineers) and the National Inspection Council for Electrical Installation Contractors (NICEIC) offer more comprehensive guidelines for the design of electrical systems and practical installation. Professional designers and installers are required to comply with the IET/NICEIC/British Standards Codes of Practice.

However, AD P provides a 'condensed' code for householders, including a new formalised way for controlling electrical works, and discouraging the tendency for 'have a go DIY'.

This requirement was introduced in order to protect people from injury and death caused by incompetent DIY electrical work.

Some of the exemptions from Part P include:

• replacing outlets (power points/sockets, control switches, ceiling roses and so on), which does not comprise actual rewiring of the installation (new fixed cabling);
• replacing the cable to a single circuit only where it has been damaged;
• refixing or replacing enclosures to an existing installation (a component);
• providing mechanical protection to existing fixed installations – that is to say, sheathing or an improved conduit, for example;
• improving or installing earth bonding (equipotential bonding, e.g. between water pipes).

Some works are permitted outside of the kitchen or special locations, or where low voltage wiring is involved (e.g. telecoms rewiring).

• AD P affects dwellings only – residential properties.
• The Institution of Electrical Engineers/IET/Building Regulations and British Standards apply to some electrical operations for the plumbing of heating systems and vice versa.

The scope of this section affects small building works as well as maintenance and repair.

Consequently, for practical purposes any new wiring works need to comply with AD P and to be carried out and tested/checked by a competent person with the appropriate copy of the British Standard 7671 Installation and Test Certificate supplied on completion of the works.

Ensure that this requirement is incorporated within any specification for works, notwithstanding that it is a statutory requirement.

AD P also summarises some 'older practice work that can be encountered in alteration work', which is worth referring to; and it provides identification for the new harmonised electrical cable colour coding.

Once an electrical installation has been completed (or where one has been altered), a BS 7671 check is required. For example, a plumber carrying out repair works to a hot water cylinder and immersion element would still be liable to establish and confirm that the part of the system being worked on had been checked in accordance with the Regulations.

As with other aspects of repairs and maintenance, ensure you have a good grasp of the existing condition of wiring when preparing a specification. Points to note:

• Ensure cables are not covered by thermal insulation. This is a common issue where insulation has been upgraded, risking overheating of the cable. Unless thermally de-rated cable is used, ensure that there is adequate ventilation and air space around the cables. This can be achieved, for example, in the roof space by cleating them on battens clear of insulation material.
• Although cables should not be run down the cavity within cavity wall properties, this is an occasional short cut. If any cavity wall insulation is being installed later or other works carried out, there is a risk of electrocution if the wall is being drilled or broken apart in the course of the works. Check for this. Also check whether existing cavity wall insulation might cause the cable to overheat.
• Check that cables have not been run as shortcuts at angles across a wall and that the correct horizontal or vertical paths have been routed.

Keeping records (and checking them too ...)

Maintain a comprehensive data file, given that property owners may need to supply technical information to prospective buyers or - where renting - to tenants. There may be a higher and ongoing duty of care for landlords - tenants do not usually have surveys - and landlords have an implied duty to let a safe property. It helps if you can prove it, and a test certificate suggests you are a reasonable and sensible landlord, not the other sort.

It is also useful to have details of wiring and other electrical work for reference when maintenance or alterations are required.

For commercial property, the data should be recorded in the Building Maintenance Manual (if it exists). It is at the very least prudent to recommend such a file to the client. If you are a property occupier then you must have such a file if you wish to demonstrate all reasonable safety precautions are routinely adopted. For example, cable runs need to be identified and the information made available before maintenance or alterations works are carried out by contractors, and this information needs to be incorporated within the pre-tender health and safety file (CDM section) on larger projects.

Services test certificates - building surveyors' duty of care - some thoughts

If you are a building surveyor acting in a supervisory role or as an employer's agent you may have a duty not just to ensure that appropriate test and commissioning certificates are provided, but also to check that they are correctly completed.

Gas or electrical certificates or other commissioning information (lifts, alarm systems, smoke or fire detector entries on electrical tests or where certified or commissioned independently of the basic electrical certificate) completed with:

• the wrong address (or only a plot number instead of the postal address);
• perhaps the wrong date (turn of the year or month often leads to errors);
• sections or client names incomplete; or
• with the wrong client address;

all might make a certificate invalid.

Such errors have lead to referrals to the HSE in recent times.

Check your terms of engagement and what duties you have to the client; and possibly for vicarious liability to tenants too.

If a landlord client (or private client who might later become a landlord) has retained you to specify or oversee works as their agent - and which include the need for service tests and commissioning - it is advisable to verify that all certificates are properly completed, and probably to keep a copy for your own records too.

Example of an item certified independently of the usual gas or electric certificates Domestic smoke alarm circuits are included on the BS7671/NIEEIC certificate. To challenge a popular assumption: this only tests the circuit and not the operation of the alarm itself. When you push the smoke alarm red button every week it only proves the battery or circuit are live and that the siren works. It does not necessarily verify the detector is detecting smoke (this you only discover when you burn the toast, etc.). But a specialist fire/smoke alarm as part of a building wide system or a commercial alarm system would probably have a completely stand-alone commissioning and test certificate.

Electrics: the basics should serve as a useful aide memoire to electrical work when you are out on a site inspection.

Wiring colours

The colours of the live and neutral wires in electrical cables changed in 2006. Red and black changed to brown and blue – the same as the wires in flexible leads to portable appliances.

Completion testing (BS 7671)

Briefly, the main tests are:

1. Continuity of the protective conductor (the earth cable). This includes not only the main earth cable but also the 'equipotential bonding conductors', i.e. the earth straps around central heating or water pipes which might be used as a secondary protective circuit to ensure that, if these components should accidentally become live, they are earthed. (Stainless steel kitchen sinks are effectively included too.)
2. Continuity of the main ring circuit conductors – that is, both the live and neutral cables.
3. Insulation resistance – this is to establish if any of the plastic insulation sheathing has been stripped off and the live or neutral cables might be touching either each other or the earth circuit and that they are operating effectively.
4. Polarity – all switches, circuit breakers and fuses need to be correctly connected to the 'phase conductor' (the live cable).

Other tests may include:

• Earth electrode resistance checks. This is to establish that all of the earth cabling is of adequate capacity to earth the system (sometimes in an upgrade a newer more substantial supply and cable is installed but parts of an older and smaller earth cable are at risk of being left in situ). Where there is an earth electrode it must be capable of conducting any escaped current to earth.
• Earth fault loop impedance and functional testing of circuit breakers.

All of the test values need to be entered on a test certificate in accordance with British Standard 7671.

• For commercial property, this should be maintained in the building maintenance and health and safety files.
• For residential property, this should be maintained within some form of building maintenance file.

Sources of information

In addition to AD P, a very useful document is Onsite Guide: BS 7671 (2001) 2004, published by the IET. This is a commentary on the 16th edition of the Wiring Regulations. Note that the IEE Writing Regulations 17th edition was published in January 2008.

The Onsite Guide provides concise notes on specification for smaller properties – predominantly residential but could include commercial properties in some instances. Its small 'handbook' format allows quick reference to deem-to-satisfy design guides and standards for installation practice and should be on the bookshelf of any surveyor involved in building works – or in the car for convenient quick reference.

It is also useful if you need to carry out some fairly basic checks of installation work (e.g. if you are acting as contract administration or clerk of works). For example, cable distances and positions, depth in plaster and so on can all be quickly checked and – if need be – demonstrated to the contractor where there are any shortcomings.