OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 25 Tools, Equipment and Machinery

Section 366 Preventing machine activation

The employer must install positive means to prevent equipment from starting up when a worker is feeding material into the equipment or a part of the worker’s body is within the machine’s danger zone.

Methods of accomplishing this include:

(1) presence-sensing devices such as:

(a) photoelectric devices that use a system of light sources and controls that can interrupt the machine’s operating cycle. If the light field is broken, the machine stops and will not cycle or will not start. This device is to be used only on machines that can be stopped before the worker reaches the danger area;

(b) radiofrequency (capacitance) presence-sensing devices that use a radiofrequency beam that is part of the machine control circuit. When the capacitance field is broken, the machine stops or will not activate. This device is only to be used on machines that can be stopped before the worker reaches the danger area. This requires the machine to have a friction clutch or other reliable means of stopping;

(c) electromechanical sensing device that has a probe or contact bar that moves to a predetermined position when the operator initiates the machine cycle. If there is an obstruction preventing it from moving to its safety position, the control circuit does not allow the machine to cycle;

(2) two-hand controls require the use of both hands at the same time to activate the machine. The operator’s hands are out of the danger area. The controls must be designed so that they cannot be operated with one hand and another part of the body; and

(3) two-hand trips require the operator to press two buttons at the same time to start the machine. Once the machine is started the operator’s hands are free to perform other tasks. The controls must be designed so that the operator cannot use one hand and another body part to activate the machine.