A HiPo near miss occurred when interlocks were used as a form of isolation.

During aggregate processing, a blockage occurred within the chute under the secondary screen. To clear the blockage access to the area protected by distance guarding was required.  The dedicated isolation point for the screen belt was not utilised, instead the interlock located on the access gate of the distance guard was relied on for the isolation, this was against the agreed SSOW and training.

Please see downloadable pdf.

• Isolation procedures should always be followed and individual locks attached by anyone entering the area.
• Limit switches/interlocks must never be used as a form of isolation. These systems break the signals on a control circuit like an emergency stop button.
• Try out must always be conducted to ensure the equipment has been successfully isolated.

Further Consideration:

• Ensure anyone working on equipment are trained in LOTOTO.
• Ensure everyone knows the isolation procedures for any plant they work on and where the isolation points are.
• Check everyone/including contractors are following isolation when working on equipment.