To: Health and Safety Enforcing Authorities
For the attention of: Local Authority Health and Safety Enforcement Managers, Health and Safety Regulators and others
This Local Authority Circular (LAC) provides technical guidance to enforcement officers and others on health and safety issues associated with electrical safety
1 This circular alerts local authority enforcement officers to the electrical hazard from the use of electrophoresis equipment which may be found in quality control laboratories etc for examining biological materials. Such laboratories may be allocated to LAs where they are a minor activity (eg. in a large office complex).
2 Electrophoresis uses electrodes in a transparent plastic tank to apply a potential difference to a gel containing biological material under examination. Voltages of 80V dc to 2.5kV dc are typical with currents ranging from 100mA to 1A. Higher ratings may be found on the larger tanks.
3 The danger is usually from contact with both poles of the supply rather than contact between one pole and earth. It is understood that there have been 3 fatal accidents in the USA and at least one serious shock incident in the UK.
4 Other techniques such as electroporation and electrotransformation which apply dc power to biological materials may also present a similar hazard.
5 No exposed live conductive parts should be accessible to the operator at any time.
6 A safe system of work should require that power supplies to tanks are always switched off before any connections or disconnections in the system are made, lids are opened or covers removed. In addition, effective safe dc isolation and/or supplementary protection by further enclosure and interlocking is necessary to ensure that an operator who forgets to switch off is not placed at risk. Isolation of the dc output by separable contacts is considered to be the safest and most cost effective method.
7 Simple control circuit interlocking by using a safety switch to operate a contact or relay which breaks the ac supply to the powerpack when the lid is opened is NOT recommended.
8 In respect of these matters attention is drawn to the requirements of the Electricity at Work Regulations 1989, in particular Regulations 4, 12, 13, 14 and 16. Where potentially dangerous voltages are used and precautions are not adequate LA enforcement officers should seek advice from an HSE Electrical Specialist through their Enforcement Liaison Officer (ELO).
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