Introduction and Scope

Advice given in this Publication is intended to assist not only installers of instrumentation and control systems and panel builders who must satisfy the tightly specified requirements of large companies and utilities, but also those installers and panel builders upon whom the client relies entirely to produce a panel to meet the end application and which also complies with legislation concerning worker health and safety.

This Publication covers:

• instruments and their control panels;

• control systems;

• general observations from an inspector's viewpoint and legal aspects.

The guidance given applies to small instruments and equipment through to, for example, the control aspects of motors and provides details relevant to those who specify, build and subsequently install and use instruments.

This Publication is intended to apply to electrically powered instrument systems and their control panels used to measure, indicate, compute, control, record, etc. and which are suitable for use in process control and similar applications. However, as the requirements are based on the safe use of electricity, they are equally applicable to electrical equipment used for other purposes.

Fundamental principles to be followed at all times are:

• that all instrumentation and control equipment should be installed to facilitate accessibility and maintenance;

• that instrumentation and control equipment should be protected against any external influence to which they may be subjected, including electromagnetic interference;

• that the overall integrity of any control system should not be damaged or destroyed as a result of examination, maintenance, authorised alteration or expansion;

• that inappropriate or unauthorised alterations to wiring or to programmes of programmable systems are to be avoided, as such alterations may alter the functionality of the equipment and may also result in the designed safety functions not being preserved;

• supplementary to the above, but not detailed in this publication, is an inherent requirement to provide effective work instructions and, where necessary, permits to work and protective clothing.

Many of the accidents and injuries ascribed to electrical faults could be eliminated by attention to detail at all stages.

This Publication makes reference to the UK Electricity at Work Regulations 1989 and it is recommended that this document is studied in conjunction with this Publication. In countries outside the UK, similar regulations are usually available and should be studied likewise.

In the UK, the employment of 'Competent Persons' to undertake work is a requirement of the Electricity at Work Regulations 1989. Such a requirement exists in many other jurisdictions. This requirement for competency should be brought to the attention of all concerned, whether it is with design, manufacture, installation, commissioning or any other activity where incompetence could compromise the safety of people and equipment.

Schemes such as CompEx™ provide training and certification for technicians working on electrical installations situated in potentially explosive atmospheres. EEMUA CompEx™ is a leading UK training, assessment and certification scheme for electrotechnical craftspersons working in potentially hazardous or explosive atmospheres, jointly developed in the 1990s through participation with industry, regulators, trades unions and others, and currently operated by JTL Ltd.

The safety requirements required when working at voltages greater than 1000 volts greatly exceed those required at low voltage. Consequently special training and clothing are required before work on high voltage power equipment is to be undertaken. It should be noted that high voltages may be found within some types of apparatus normally operating from low voltage sources.

Where hazards may be attributable to safety issues other than electrical, other regulations are likely to be applicable. This Publication does not deal with these non-electrical safety issues. Installers and panel builders should make themselves separately aware of their requirements.

For instance, for chemical agents or potentially explosive atmospheres, in the UK the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) will need to be considered. These Regulations implement the EU Directive on the safety and health protection of workers in potentially explosive atmospheres (1999/92/EC) and relevant parts of the Directive on chemical agents (98/24/EC).

For electromagnetic compatibility issues, the EMC Directive (2004/108/EC) is mandatory for all new equipment throughout the EU. International equivalents operate in most other countries. By meeting electromagnetic compatibility requirements, electromagnetic interference affecting the operation of electrical and electronic equipments is minimised. With poorly designed equipment, it is possible that electromagnetic radiation from one item could affect the operation of another item.

For equipment provided for work in general, regulations such as the UK Provision and Use of Work Equipment Regulations, have to be met.

Under regulations, such as the UK Construction (Design and Management) Regulations, there is a duty on employers to ensure that risks are designed out. The safety of persons and plant is at risk where equipment fails to comply with the regulations.