OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 5 Confined Spaces

Section 56 Tending worker

With proper communication, work in a confined or restricted space is made easier, safer and in many cases, more productive. Care must be taken when selecting communication equipment for this unique work environment. Confined or restricted spaces are very different from any other work area and must be treated accordingly.

Radio signals do not penetrate metal or concrete reinforced with re-bar, which describes a majority of confined or restricted space environments, creating dead spots or reducing signal strength. Messages can become garbled or are not received. This prevents continuous communication in certain types of spaces.

Radio equipment is extremely effective when used by safety attendants outside spaces to maintain contact with their base or, in the event of a problem, to call for rescue assistance.

The preferred choice for reliable communication in confined or restricted spaces is a hard-line full duplex system, which allows hands-free communication between a tending worker and workers inside the space.

No matter which method of communication is chosen, the equipment selected should be suited to the particular work environment. It should be extremely rugged, resistant to chemicals, environmentally sealed and intrinsically safe if used in a potentially hazardous location.

As required by subsection (3), a tending worker – a competent worker trained in the evacuation procedures in the emergency response plan and who is present outside the confined space, at or near the entrance – is required under the following four conditions:

(a) the oxygen content of the atmosphere inside the confined space is less than 19.5 percent by volume;

(b) the oxygen content of the atmosphere inside the confined space is greater than 23.0 percent by volume;

(c) the concentration of a substance listed in Table 2 of Schedule 1 inside the confined space is greater than 50 percent of its occupational exposure limit; or

(d) a hazard other than one listed in clauses (a), (b) or (c) is identified by the hazard assessment and the hazard cannot be eliminated or effectively controlled.

The role of the tending worker is to monitor the safety of the person(s) working inside the confined space and to take action if an emergency arises. This tending worker must

(a) keep track at all times of the number of workers inside the confined space,
(b) be in constant communication with the workers inside the confined space,
(c) have a suitable system for summoning assistance, and
(d) not leave the area until all workers have left the confined space or another tending worker is in place.

If the four conditions listed above do not apply to a particular confined space, then a tending worker as described above, having the duties described above, is not required. Instead, as required by subsections 56(1) and 56(2), a competent worker designated by the employer must be in communication with the worker in the confined space. In some cases this designated worker may be in a nearby vehicle, or may be at a central dispatch location. The competent worker designated by the employer must have a suitable system for summoning assistance in the event of an incident or emergency.