11. Isolation of Energy and Control of Materials Movement | Confined Spaces Guideline

• Issued: September 2006
• Revised: July 2011
• Content last reviewed: July 2011
• PDF Version [ 343 Kb / 72 pages | Download Adobe Reader ]

Disclaimer: This resource has been prepared to help the workplace parties understand some of their obligations under the Occupational Health and Safety Act (OHSA) and regulations. It is not legal advice. It is not intended to replace the OHSA or the regulations. FOR FURTHER INFORMATION PLEASE SEE FULL DISCLAIMER

What is meant by "isolation of energy"?

Workers must be protected against any hazards associated with the moving parts of equipment or electrical energy inside the confined space by ensuring that they are de-energized or otherwise controlled.

What is meant by "control of materials movement"?

The purpose of this requirement is to ensure that no material or contaminants enters or moves within the confined space through process lines, drains, vents, etc. In addition, employers need to protect workers against any collapse or shift of material.

What is meant by "blanking or disconnecting piping"?

The purpose of this requirement is to ensure that no material or contaminants enters the confined space through process lines, drains, vents, etc.

Blanking is the insertion of a solid metal barrier, called a blank, between the flanges of two sections of pipe. In this instance the confined space extends to the blank. Disconnecting is the removal of a section of piping to ensure that no material can flow into the confined space. Note that care must be taken to ensure that high-pressure or toxic material cannot pass across the disconnected space - for example, high pressure steam can cross between the sections of pipe if the piece that has been removed is in-line with the two sections of pipe. (In this instance, the section removed should be an elbow or other fitting to ensure that the two sections of pipe are not in line).

What is an example of "other adequate means"?

If blanking and disconnecting is not practical in the circumstances for technical reasons, then “other adequate means” can be taken. This may include such measures as a double-block and bleed system or the formation of a properly engineered “freeze plug”, depending on how much protection they actually provide, i.e. the measures must be “adequate”.

The type of substances that may enter the space from piping, drains, vents, etc. would also be a significant factor in determining adequacy and what other means may be taken. For example, a single isolating valve to prevent the flow of toxic substances (e.g., poisonous gas) and substances that may pose a drowning, engulfment, or entrapment hazard, is not adequate, but a double-block and bleed system may be adequate.

In addition, although locking out isolated valves is not specifically referenced in the confined space provisions, it could be a reasonable precaution that could be taken, and should be considered depending upon the substances that may enter the space.

Do all moving parts of equipment inside a confined space need to be de-energized?

No, only equipment that could endanger a worker, such as unguarded equipment, or equipment that may have exposed moving parts or that may create a pinch point, require de-energizing or blocking to prevent movement. For example, a properly guarded pump or fan would generally not need to be de-energized. However, in a confined space in which flammable, combustible or explosive agents might accumulate, the same equipment would be de-energized or designed so that it does not create a spark.

What other means could be used to protect workers from contact with electrical energy?

Measures could include the installation of temporary barriers or shields or, if not practicable, the provision of adequate personal protective equipment.

Note: CSA Standard Z460 Control of Hazardous Energy - Lockout & Other Methods may be considered when developing best practices to comply with this section.

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