The topic of electrical power systems is concerned with risks arising from electrical distribution systems and equipment at major accident hazard sites. Specifically, it is concerned with:
- the management, design, installation, operation and maintenance of electrical power systems so that they provide the necessary reliability, availability and survivability and so that they prevent danger to personnel
- the initiation of major accidents by electrical equipment through fire and explosion
Electrically powered hazardous installations such as large-scale chemical manufacturing processes should be designed to fail to a safe state on loss of electrical power, however, in certain circumstances it may be necessary to maintain electrical power to ensure safety. In some situations partial failure of the electrical distribution network may lead to more severe consequences than complete failure.
Electrical distribution systems generate, store and transmit extremely large amounts of energy. Uncontrolled releases of electrical energy, for example from catastrophic failure of equipment or poorly designed or maintained equipment, have been seen to result in electrical fires and explosions that are dangerous in themselves but can also initiate major accidents at major hazard sites.
The risks arising from the reliability, availability and survivability of electrical supplies and from catastrophic failure of electrical equipment should be managed by:
- identifying the consequence of complete and partial failure of electrical supplies
- identifying the consequence of catastrophic failure of electrical equipment
- ensuring the electrical power system integrity is consistent with any risk reduction claimed
- installing electrical equipment remote from major hazard installations or in protected locations
- designing electrical distribution systems to discriminate faults to prevent cascading a failure across the site
- selecting electrical equipment that is capable of withstanding anticipated fault currents
- maintaining electrical equipment and protection devices
- having robust safe systems of work and competency assurance to ensure electrical systems are only operated and maintained by competent persons
Guidance on risks arising directly from electricity is provided on the electrical safety at work pages of this website.
Technical Standards and Guidance
Regulations
- Control of Major Accident Hazards Regulations
- The Management of Health and Safety at Work Regulations 1999
- Electricity at Work Regulations
Technical Standards
Industry Publications
- Energy Institute Guidance on assessing the safety integrity of electrical supply protection
- IET Code of Practice for Electrical Safety Management
HSE Guidance
- The Electricity at Work Regulations 1989. Guidance on Regulations
- Electricity at work: Safe working practices
- Keeping electrical switchgear safe