Standard inspections

Inspection and testing of electrical installations is an activity that does not always receive the attention that it deserves or needs. It is an essential part of the installation process and ensures that the scheme meets the criteria of BS 7671 and the Electricity at Work Regulations.

Installations must be proved to be safe, correctly selected and installed. Ultimately, inspection and testing proves the design of the installation.

Getting inspection right

Detailed inspections need to be carried out at the right time during the installation process. This is a requirement of BS 7671, as access cannot always be gained to certain areas once the installation is complete. It is also good practice.

Early identification of a problem can mean the cost of rectification is far less than if the remedial work was carried out at completion. This will also mean that problems are inspected out. For example, if the installer does not realise that a defect exists, the same problem may be repeated time after time in the installation.

Findings from inspections therefore need to be fed back to the installer during the installation phase, as do particular requirements from specifications. The target is zero defects during the inspections, and ultimately at completion.

Another aspect of inspection is ensuring that all relevant parties are invited to attend at the same time, thus reducing the amount of inspections carried out and the resultant discrepancies between any snags raised. In some cases the contractor, principal contractor, consultant and architect carry out separate inspections, which then result in a paperchase of snag sheets and disputed snags, with little benefit to anybody. It is important therefore that the process is planned and formally agreed. Also, that records of both inspection and snagging are produced and kept throughout the contract.

Equally important is the testing of the installation, again to confirm the design and safety. Testing needs to be carried out by a competent person and must be planned to ensure the methods and procedures are safe for the tester and persons in and around the area under test.

Adding to installations

Where works carried out are an addition or alternation to an existing system, inspection and test procedures need to extend to parts of that existing system.

That is not to say that a full inspection of the whole installation is required for each addition to a circuit. It must be proved that where, for example, the altered circuit relies on Earthed Equipotential Bonding and Automatic Disconnection of Supply (EEBADS) for protection against indirect contact, the main earthing and equipotential bonding is in place and suitable.

Also, where an addition to a system increases or changes the type of load, the size rating and suitability of the main and any associated switchgear must be confirmed. Frequently this confirmation is not given.

Problems are cited with access or even locating equipment or earthing and bonding connections. This is clearly not an acceptable reason for not doing what is an essential inspection with regards to the safe operation of the new parts of an installation. Where real difficulties exist the client should be made aware in writing and further arrangements made to gain access.

Existing systems

The inspection of existing installations is covered comprehensively in BS 7671 and associated guidance. The emphasis of periodic inspection and test should be on the inspection process. This may then be supplemented by appropriate testing, which may be a sample test.

The common factor with all inspection, testing and maintenance activities is the need to produce and keep detailed records. This is a requirement of BS 7671

The level of inspection and testing needs to be planned and agreed prior to commencing. This will have to be recorded on the Periodic inspection report issued on completion of the works. This level, known as the extent and limitation, is dependent on a number of factors that would influence the condition and rate of deterioration of the installation.

Factors include environmental conditions such as ambient temperature and humidity, the ingress of water or foreign bodies, the likelihood of physical damage due to impact or vibration; and any corrosion as a result of these or due to dissimilar metals.

Other considerations should be how, and by whom, the building is used. A small office installation would be less likely to deteriorate as quickly as an industrial workshop. The use of the building would determine how often it would be subjected to periodic inspection. Detailed guidance on the suggested frequencies for types of installation is available in IEE Guidance Note 3. These are only suggested frequencies and consideration should also be given to the availability of records from previous inspections, change of use of an installation or local authority licensing requirements.

Maintaining inspections

It follows that once a system is put into service it should become subject to a maintenance regime. The 2001 edition of BS 7671 made it possible for periodic inspection and testing to be replaced by an ‘adequate regime of continuous monitoring and maintenance of the installation by skilled persons’.

In determining what is required for an effective regime of maintenance, the factors already discussed must be assessed to identify the influences on the continued safety of the installation. Also, to ensure that the installation and plant continues to operate, with regard to production and continues to operate efficiently without causing harm to the environment.

Different regimes of maintenance range from breakdown (where items are replaced or repaired after it fails) to preventative (which involves planned maintenance being carried out during shutdowns at specific intervals). For complex systems, condition monitored maintenance is carried out where the work is initiated by a preset alarm, for example temperature, noise or vibration.

Meeting the standards

The common factor with all inspection, testing and maintenance activities is the need to produce and keep detailed records. This is a requirement of BS 7671 and is essential in meeting the Electricity at Work Regulations 4(2). BS 7671 provides model forms of certification; these have been developed by the ECA and NICEIC for ease of use by contractors.

It is important that the differences between these documents are understood to ensure the correct form is used. The key documents are the Electrical installation certificate, the Minor electrical installation works certificate and the Periodic inspection report.

The Electrical installation certificate should be issued for all new installation work that involves the provision of a new circuit. This includes complete installations and alterations and additions to a system. The certificate must include schedules of the inspections carried out and test results. Each of the installation’s design, construction and inspection and test phases must be signed for by a competent person.

Where the work does not include a new circuit, but is an extension to an existing circuit, a Minor electrical installation works certificate is required. Again, this should include a signature for each element, although in this case one person is generally responsible for all three.

The final document, the Periodic inspection report is, as it states in the name, a report not a certificate. Its purpose is to identify any damage, deterioration, defects and dangerous conditions that may give rise to danger.

With all these considerations, and taking into account the additional needs of Part P of the Building Regulations – which requires certification for compliance in addition to certification required by BS 7671 – inspection, testing, maintenance and detailed record keeping is an activity that needs careful consideration at all stages of the installation process.