What is BS 7909 all about?

Electricity is powerful and often the cause of fires, injuries and even death. At events the risks associated with electricity are greater because of the temporary nature of the distribution system. A lack of adequate mechanical protection, varying demands, unpredictable weather and unusual loads all can affect the effectiveness of protection methods used. This page outlines the background, methods and need to ensure electrical safety at events. It is a short briefing guide aimed at event managers, local authorities and the like. The law All employers have a legal duty to ensure that working environments are electrically safe (Electricity at Work Regulations 1989; ‘EaWR’). They also have a duty to ensure that the equipment used in the workplace is electrically safe as well (Provision and Use of Work Equipment Regulations 1998, ‘PUWER’). In essence, PUWER requires us to inspect work equipment regularly to make sure it is safe to use, and this is where the concept of ‘portable appliance testing’ (more colloquially known as ‘PAT Testing’) stems from.  The EaWR is concerned with the electrical system as a whole, which includes the distribution cables and boxes as well as the equipment connected to it. It requires the system to be designed and installed by competent people and for it to protect against the hazards that electricity can create. Complying with the law British Standard BS 7671 is the principle guide to electrical safety in the UK. It is better known as the IET Wiring Regulations, currently in its 17th edition (and often referred to as such). The Health and Safety Executive holds BS 7671 in high regard, to the extent that it has written an endorsement in the introduction which states that installations that comply with BS 7671 are likely to enable the requirements of the EaWR to be met. BS 7671 does invoke the use of other standards which may have to be used alongside it. In this context the most relevant is BS 7909 which is a guide for temporary power systems at events. So to comply with the IET Wiring Regulations at an event, BS 7909 has to be complied with too. By inference both standards are therefore required to enable compliance with the EaWR. Both are also listed in the Memorandum of Guidance on the EaWR published by the HSE. BS 7909 deals specifically with the setting up, management and some related technical issues for the temporary electrical systems used at events. Events usually include (but not exclusively) festivals, location filming, agricultural shows, TV OBs, theatre, sporting events, pageants and so on.   What is a temporary electrical system? Although BS 7671 is concerned with ‘electrical installations’ it calls any assembly of electrical equipment an ‘installation’, whether temporary or permanent. If it is temporary, it is designed for a particular purpose and will be removed when no longer required for that purpose. That purpose may a one-off gig, a film shoot, a winter ice-rink or a summer festival. There is no defined period of how long temporary may be. It’s better to consider it as not being permanent. Equally it is important to note that BS 7909 applies to systems of a ‘plug’n’play’ nature, where all the distribution equipment and cables are ready made and the whole system can (largely) be assembled without the use of tools. If it is being manufactured from scratch then BS 7671 only applies, but most event companies only use pre-assembled and tested stock distribution equipment so BS 7909 would more often than not apply. Also note that BS 7671 has particular requirements for fairgrounds and exhibitions which are not covered by BS 7909 specifically. So it doesn’t matter whether the power comes from a generator or a building, the event is indoors, outdoors or in a marquee. If the intention is to remove it at some point, it’s temporary. Tell me about BS 7909 in a nutshell. Essentially it requires events to design their systems in accordance with the Wiring Regulations; i.e. to ensure systems work effectively and protect against the risks of shock and fire. A main focus is on management of the event and it tries to help contextualise the requirements of the Management of Health and Safety at Work Regulations 1999. It requires the event manager (which may be a promoter, event manager, producer, production manager etc) to appoint someone electrically competent to oversee the electrical system. Under BS 7909, this person is called the ‘Senior Person Responsible’ (SPR). The standard also splits electrical distributions into two categories; ‘small/simple’ systems and ‘large/complex’. The guideline is that anything under 6kVA (typically the same as 6kW worth of power, equivalent to around three kettles) is classed in the small/simple category. The key to the application of the small/simple category is that it is simple and typically used within a building - the supply would usually be derived from the ordinary sockets on the wall. There won’t be much equipment – examples may be small press conferences, indoor display stands or filmed interviews. It also allows for the SPR to be an instructed person who has been directed in the use of a simple plug-in tester, but who may not be electrically skilled. There are no requirements for completion documentation, but PAT records for equipment must be checked and the supply verified.  Anything else that doesn’t fit into that classification is considered large/complex. That may include relatively small systems but which are run from a generator, or extension leads taken from a building to deliver power to an outdoor event. All of these situations require someone electrically skilled to assess the additional risks and put in suitable protection methods. Large systems need a bit of planning and should be designed and tested. The testing need not be done on every circuit as the equipment has already been checked, the designer though needs to ensure that the protective measures will work effectively for the supplies used. Documents showing that the system has been designed and checked need to be completed (called ‘completion certificates’) and copies should be given to the person ordering the work as well as the property/venue owner if requested. Some examples of the documents are appended to this document. Testing The testing needs to be completed before the system is handed over to the rest of an event crew for general use and the test results noted. The certification would normally be completed when everything is operational and the SPR has satisfied himself that the system is safe and works effectively. Temporary systems need re-testing and re-certification (or amended certificates) when substantial changes in the distribution occur. Each event is different, but examples may be: New locations – each time a system is put together in a new location or venue; Significant additions of equipment; e.g. a new multiple channel dimmer and lighting circuits or a dining bus, rather than a couple of individual light fittings or an extension lead to power a kettle. Changes of supply – e.g. going from using a building or venue supply to a generator. Damage or interference to the equipment, including unforeseen environmental effects (flood, fire etc).  Note that the context should be considered in each case - consider a small film shoot using a few lights, associated distribution and a generator moving from location to location.  If the same cabling, distribution, equipment and source of supply are used at each location, then the results will always be broadly the same. Accordingly some rudimentary checks at each subsequent location may suffice after the first full assessment. BS 7909 also discusses earthing practices and procedures in some detail. Basically the mass of earth that you stand on is often (but not always) used as a safety measure by providing a route back to the power supply for fault currents, which in turn causes fuses or circuit breakers to operate when there is a problem. The earthing arrangements in a temporary system need careful consideration particularly where generators are used or cables are taken in/out of buildings. If you see an earth ‘spike’ (normally a metal rod or tray) under the wheels of a generator or an earth cable connected to an item of street furniture such as lamppost or bus shelter, questions should be asked as these are indicators of ineffective or even potentially dangerous earthing practices. Bibliography The IET Wiring Regulations 17th Edition Electricity at work regulations 1989 Memorandum of guidance on the electricity at work regulations (HSR 25) Provision and use of work equipment regulations 1998 BS 7909 Code of practice for temporary electrical systems for entertainment and related purposes

A brief guide to electrical safety at events

Electrical safety at events