Emergency operation controls

Provide appropriate normal and emergency stopping controls for the machine and risks. An emergency stop initiates a safe stopping function; it does not necessarily disconnect every supply, stop movement instantly or remove stored energy. It is not a substitute for guarding or secure isolation before maintenance. The key requirements for emergency controls are that they:

• are stable
• have suitable warnings, such as warning signs by dangerous parts and, in some cases, visible and audible warnings such as flashing beacons and sounders that warn of the start-up or movement of machinery
• are clearly identified, generally coloured red on a yellow background, and are suitably marked, with labels on control panels, safe working loads, maximum speeds, direction of movement and so on
• are within easy reach of the operator, which applies to every normal workstation where operators interact with the machine
• use palm or mushroom-shaped buttons
• need manual resetting, which means the device must latch in the activated position and need a deliberate action to reset it
• are unguarded, so that easy access to the device is not blocked, taking into account the PPE that workers must wear
• leave operators with adequate space to move around the equipment safely
• are supported by adequate and suitable lighting for the operation of the machinery, so that its movements, controls and displays can be seen easily

One important consideration is the potential for accidental operation. Depending on the machine or process, unintended operation of an emergency stop may cause significant lost production or damage to equipment, including to the emergency stop itself. In such cases it is reasonable to protect the device from accidental operation, as long as the protection does not impede its use in an emergency.

Summary notes for Element 9 · Cheat sheet · Glossary. A study aid, not published or endorsed by NEBOSH.