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Emergency isolation in kitchens, workshops, School labs etc

Increasingly, Heath and Safety Executive officials are requiring that work and training areas, such as kitchens, workshops, computer rooms, laboratories etc have some form of Emergency disconnection of power supplies.

Generally this will take the form of  a contactor, through which the main power supply to the concerned area will be fed, which can be de-energised by means of an Emergency Stop buttons in key areas of the work place. It is usual to use a latching circuit that will require a specific action AFTER resetting of the Emergency Stop to re-establish the supply. This is to prevent inadvertent re-starting of supply/machinery on resetting the E-Stop. This also has the advantage of preventing unexpected resumption of power and starting of machinery after a power cut etc.

The Reset may be in the form of a simple momentary normally open pushbutton, or where greater levels of safety/security are required, eg schools, a spring return key switch, so that only an authorised person with a key can re-establish the supply.

Attached is a diagram illustrating the principle of a typical latching circuit. Such a circuit is acceptable in many cases but it should be confirmed with your Health and Safety advisor that this will be suitable for your application. They will also be able to advise on how many E-Stops are required, their locations and the location and type of reset required.

This diagram is purely a schematic of how such control can be achieved. It remains the responsibility of the installer to ensure that all local and national wiring and safety directives/regulations etc, in particular BS7671 (at time of writing 17th Edition)  are met with regard to circuit protection, wiring installation, personnel protection etc.

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