The checks and inspections that should be carried during formal visual inspections and by the user should reveal most potentially dangerous faults. However, some faults, such as loss of earth integrity (e.g., broken earth wire within a flexible cable), deterioration of insulation integrity, or contamination of internal and external surfaces, cannot be detected by visual examination alone. Such faults can only be reliably detected by a combined visual inspection and a test. 

Combined testing should be carried out periodically to back up the checks and inspections and is likely to be justified: 

• Whenever there is reason to suppose the equipment may be defective and this cannot be confirmed by visual examination.
• After any repair, modification or similar work. 
• At periods appropriate to the equipment, the manner and frequency of use and the environment. 

The inspection carried out in conjunction with testing should usually include checking: 

• The correct polarity of supply cables.
• The correct fusing. 
• Effective termination of cables and cores. 
• The equipment is suitable for its environment.

People testing portable electrical equipment should be appropriately trained. It is the employer’s duty to make sure that they are competent for the work they are to carry out. There are two levels of competency: 

• Level 1: A person not skilled in electrical work routinely uses a simple ‘pass/fail’ type of portable appliance tester where no interpretation of readings is necessary. The person would need to know how to use the test equipment correctly. Providing the appropriate test procedures are rigorously followed and acceptance criteria are clearly defined, this routine can be straightforward. 
• Level 2: A person with appropriate electrical skills uses a more sophisticated instrument that gives readings requiring interpretation. Such a person would need to be competent through technical knowledge or experience related to this type of work.

Combined visual inspection and testing requires a greater degree of competence (in terms of knowledge, training and experience) than for a visual inspection alone, because appropriate electrical knowledge is needed to undertake the tests and interpret the test results. However, it can often be carried out by a competent employee.

Although a good initial level of safety can be achieved by correct selection and use of equipment and its connectors and cables, lasting safety can only be attained by ongoing and effective maintenance. 

An electrical accident can lead to a potentially fatal electric shock, or fire affecting the whole premises. The maintenance plan should therefore be designed to be proactive, i.e., planned to prevent incidents arising, rather than reactive, where action is taken following an incident or accident. The action taken should be appropriate to the risk, e.g., the frequency of inspections and any necessary testing will depend on the type of equipment in use, how it is used, how often, and where it is being used. Maintenance will need to be carried out more frequently where the risk is high, e.g., on construction sites, and less frequently where the risk is lower, e.g., in offices. 

Effective maintenance of portable electric equipment can be achieved by a combination of: 

• Checks by the user.
• Formal visual inspections by a competent person.
• Where necessary a combined inspection and test, also known as a portable appliance test (PAT), by an electrically competent person. 

The aim of these checks is to determine whether the equipment is fully serviceable or whether remedial action is necessary to make sure it is safe to use. Managers should follow up these procedures by monitoring the effectiveness of the system and taking action where faults are found, particularly when faults are frequent.

The legal requirements relating specifically to the use and maintenance of electrical equipment are contained in the Electricity at Work Regulations 1989. These regulations apply to all work activities involving electrical equipment. They place duties on employers, the self-employed and employees (subsequently referred to as “duty holders”). These duties are intended to control risks arising from the use of electricity. 

The regulations require that electrical systems and equipment must be maintained, so far as reasonably practicable, to prevent danger. This requirement covers all items of electrical equipment including fixed or portable equipment. 

The regulations do not specify what needs to be done, by whom or how frequently (i.e., they do not make it a legal requirement to test all portable electrical appliances every year). This allows the duty holder to select precautions appropriate to the risk rather than having precautions imposed that may not be relevant to a particular work activity. Note that even if a contractor is used to carry out maintenance procedures, the duty holder still has overall responsibility for complying with the law. For more information see HSE publication “HSR25 Memorandum of guidance on the Electricity at Work Regulations 1989”. 

There are also legal duties on manufacturers and suppliers covering the initial integrity (safety) of new work equipment. There are general duties covering the use and maintenance of work equipment, designed to ensure that it remains in a safe condition.

The person using the equipment should visually inspect it before use and check for signs of deterioration, for example: 

• Damage (apart from light scuffing) to the supply cable, including fraying or cuts.
• Damage to the plug or connector, e.g., the casing is cracking, or the pins are bent. 
• Inadequate joints, including taped joints in the cable.
• The outer sheath of the cable is not effectively secured where it enters the plug or the equipment. Evidence would be if the coloured insulation of the internal cable cores were showing.
• The equipment has been subjected to conditions for which it is not suitable, e.g., it is wet or excessively contaminated. 
• Damage to the external casing of the equipment. 
• Loose parts or screws.
• Evidence of overheating (burn marks or discolouration). 

These checks also apply to extension leads, plugs and sockets. A user check should be made when the equipment is taken into use and during use. Any faults should be reported to the relevant manager and the equipment taken out of use immediately. Managers should take effective steps to ensure that the equipment is not used again until it is repaired by a person competent to carry out the task.

An important part of a maintenance regime is the formal visual inspection. Such inspections are necessary because they can reveal most potentially dangerous faults. They can normally be carried out by a member of staff who has sufficient information and knowledge of what to look for, what is acceptable, and have been given the task of carrying out the inspection (that is only if they are competent to do the task). To avoid danger, trained people should know when the limit of their knowledge and experience has been reached. Simple, written guidance relating to the formal visual inspection can be produced that summarises what to look for and which procedures to follow when faults are found or when unauthorised equipment is found in use. This guidance can also help equipment users. 

These inspections can help to control the risks and to monitor the user checks. A competent person should carry out regular inspections that include checks similar to those that a user of portable appliances should carry out.

As part of the visual inspection, you should also consider whether: 

• The electrical equipment is being used in accordance with the manufacturer’s instructions.
• The equipment is suitable for the job.
• There has been any change of circumstances.
• The user has reported any issues. 

Additional checks could include removing the plug cover to ensure: 

• There are no signs of internal damage, overheating or water damage to the plug.
• The correct fuse is in use (for moulded plugs the fuse can be checked) and it is a proper fuse, not a piece of wire, nail etc. 
• The terminal screws are tight.
• The cord grip is holding the outer part (sheath) of the cable tightly; and no bare wire is visible other than at the terminals. 
• The wires including the earth, where fitted, are attached to the correct terminals (see Figure below).

The formal visual inspection should not include taking the equipment apart. This should be confined, where necessary, to the combined inspection and testing.

The formal visual inspections should be carried out at regular intervals. The period between inspections can vary considerably, depending on the type of equipment, the conditions of use and the environment. For example, equipment used on a construction site or in a heavy steel fabrication workshop will need much more frequent inspection than equipment such as computers in an office. In all cases, however, the period between inspections should be reviewed in the light of experience. Faulty equipment should be taken out of service and not used again until properly repaired. If necessary, it should be tested.

The pattern of faults can help managers decide what action to take, depending on whether the faults show:

• The wrong equipment is being selected for the job.
• Further protection may be necessary in a harsh environment.
• The equipment is being misused.

The Electricity at Work Regulations 1989 require that any electrical equipment that has the potential to cause injury is maintained in a safe condition. However, the Regulations do not specify what needs to be done, by whom or how frequently (i.e., they don’t make inspection or testing of electrical appliances a legal requirement, nor do they make it a legal requirement to undertake this annually).

Determining the frequency of inspection and testing is a matter of judgement by the duty holder and should be based on an assessment of risk. It is recommended that this is carried out as part of the general risk assessment.

The table below sets out the suggested initial frequency for the various types of checks on portable electrical equipment. It gives suggested starting intervals when implementing a maintenance plan. Where one figure is given, this is a guide for anticipated average use conditions; more demanding conditions of use will require more frequent formal visual inspections, and/or combined inspections and tests. Where a range is shown, the shorter interval is for more demanding conditions of use and the longer interval is for less demanding conditions. Alternatively, the duty holder may wish to seek advice from a competent person who has the knowledge and experience to make the necessary judgement, e.g., original appliance manufacturers or suppliers, or relevant trade associations. 

Note that the suggested initial frequencies for inspection and testing given in table are not legal requirements. It is up to the duty holder, seeking appropriate advice where necessary, to assess the conditions affecting equipment, which may lead to potential damage and/or deterioration. This information should determine the maintenance plan. Over time, and with practical maintenance experience, it may be possible to extend maintenance intervals if results of checks, inspections or tests show that few faults are found. However, if faults are common, it may be necessary to reduce intervals or take other action to improve maintenance and reduce risk.