OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 15 Managing the Control of Hazardous Energy

Section 212 Isolation

Subsection 212(1)(a)

The employer is responsible for ensuring that the work activity is performed safely. Specifically, work cannot be performed until the machinery, equipment, or powered mobile equipment has come to a complete stop (except as permitted by subsection 212(2)), all sources of hazardous energy have been isolated by an energy-isolating device and the device has been secured. An employer can choose from three approaches to securing an energy-isolating device:

(1) by individual workers (see section 214),
(2) by a group (see section 215), or
(3) by a complex group process (see section 215.1).

Subsection 212(1)(b)

“Rendering inoperative” may involve removing vital parts, putting blocking in place, pinning, or other equally effective methods. Whatever method is used, it must provide a level of worker protection equal to or greater than that provided by isolating and securing. If such alternate practices are used, it is important to advise workers that the method is for energy control and must not be altered.

While this approach typically creates a “zero-energy” states it can also result in residual energy being contained in element(s) of the machine, equipment, or powered mobile equipment. In this case, a hazard analysis can indicate if further hazardous energy control may be needed.

Subsection 212(2)

In some instances, it may be necessary to work on equipment while it is operating e.g. troubleshooting, minor adjustments, testing, etc. This approach is only justifiable if it is required by the manufacturer or it is not reasonably practicable, in the case where there are no manufacturer specifications, to render the equipment inoperative. The approach cannot be used simply because it is more convenient than isolating and securing. In this case, the employer must develop and implement written procedures for control of identified points of hazardous energy to ensure that the work is performed safely. It is suggested that workers be involved in the preparation of these procedures and controls. Section 8 of the OHS Regulation requires that the procedures be in writing and available to workers.

Subsection 212(3)

When the work activity involves piping, a pipeline, or a process system that contains a “harmful substance” as defined in the OHS Code, the employer must stop or reduce to a safe rate the flow of product in the piping, pipeline or process system. The location at which the work is to take place must then be isolated from the flow and the isolation secured in accordance with section 215.4.

Energy-isolating devices

Before carrying out the work, all energy-isolating devices that control an energy source and will be involved in the isolation must be located. This may include isolation points in different areas e.g. material conveyor that runs through two operating units. Examples of an energy-isolating device include

(a) a manually operated electrical circuit breaker,
(b) a disconnect switch,
(c) a line valve, and
(d) a block or similar device that blocks or isolates energy.

Push buttons, selector switches and other control circuit type devices are not energy-isolating devices.

Cord-connected and permanently connected electrical equipment

When work is done on cord-connected electrical equipment e.g. repairing a radial arm saw, changing the blade on a circular saw, cleaning a delicatessen’s meat slicer, etc., a worker can isolate the equipment by securing an isolating device to the electrical plug or, more practically, rendering the equipment inoperative. An acceptable approach to rendering the equipment inoperative is for the worker doing the work to

(a) disconnect the plug from its electrical supply,
(b) keep the plug in sight and within reach so that no one else can accidentally plug in the equipment, and
(c) keep the plug under his or her exclusive and immediate control at all times while working on the equipment.

If the worker leaves the equipment unattended and the work is incomplete, then the worker must verify that the plug is disconnected from its electrical supply before the worker resumes work on the equipment. The worker must then follow steps (b) and (c) as described above. In the case of permanently connected electrical equipment, the worker must secure the equipment’s energy-isolating device(s) e.g. circuit breaker, disconnect switch, etc. before proceeding with the work.

Securing devices

To ensure that there is no inadvertent release of energy or energization, the energy-isolating device(s) must be physically secured in the isolating position. A securing device is anything such as a personal lock that holds an energy-isolating device in its off or safe position (see Figure 15.1). The device must be “positive”, meaning that once secured into position, it cannot fall off or allow the energy-isolating device to move from its off or safe position. A dowel rod placed in a valve handle, duct tape across a circuit breaker or a sign placed above a box containing fuses that have been removed form an electrical panel would not be “positive” securing devices. The securing device or mechanism must be strong enough to withstand inadvertent opening without the use of excessive force, unusual measures, or destructive techniques e.g. metal-cutting tools.

Figure 15.1 Examples of securing

In some situations, several energy-isolating devices may be locked near one another and must be secured at the same time. One approach is to use a personal lock to secure each energy-isolating device in its off or safe position. Also acceptable is the practice of running a cable, bar or chain through the lock points of the energy-isolating devices (once they are in the off or safe position), then securing the cable, bar or chain against removal with a personal lock. If this approach is used, the following conditions apply:

(1) the strength, diameter and routing of the cable, bar or chain must be sufficient to keep the energy-isolating device in the “off” or “safe” position; and
(2) the construction and strength of the securing devices must be sufficient to prevent their removal without tools.

There is no limit on the length of cable, bar or chain that is acceptable, or the maximum number of energy-isolating devices that may be secured at one time. The system must provide a level of worker protection that is at least as good as if there was an individual securing device on each energy-isolating device.

Use of warning tags

While there is no requirement in the OHS Code to use a warning tag, if one is used it should indicate that the machinery, equipment, or powered mobile equipment to which it is attached is not to be operated until the tag is removed.

If used, such a tag should be securely fastened to the energy-isolating device. If the warning tag cannot be attached directly to the energy-isolating device, it should be located as close as safely possible to the device, in a position that will be immediately obvious to anyone attempting to operate the device.

Warning tags should be standardized so that their meaning is immediately clear to all workers. This may include standardizing colour, size, shape, and the format and type of information printed on the tag.

Hazardous energy control in electric utility industry

The electric utility industry must follow two different safety regulations when dealing with the control of hazardous energy – Alberta’s Electrical and Communication Utility Code (ECUC) and the OHS Code. The requirements of the ECUC apply to electric utility systems operating at voltages greater than 750 V i.e. generation, transmission and distribution systems, and to the auxiliary, metering and control circuits operating at lower voltages that affect or influence these high voltage systems. Strict adherence to the requirements of the ECUC ensures the safety of workers working on such systems and circuits. This is achieved through the use of elaborate procedures involving an operator-in-charge, voice commands, non-personal locks and/or warning tags.

For voltages and systems other than those described above, the electric utility industry must meet the requirements of this Part of the OHS Code.