Confined Space Entry


A confined space can be defined as a " tank, process vessel, underground vault, tunnel, duct, or other enclosure, not intended for human occupancy except for the purpose of performing work:

  • that has a limited number of openings for entry and exit
  • that has poor natural ventilation
  • in which there may be an excessive oxygen atmosphere
  • in which there may be an airborne hazardous substance

Confined spaces can present safety and health hazards under the following circumstances:

  • Oxygen deficiency or excess oxygen
  • Excessive concentrations of hazardous chemicals
  • Excessive concentrations of flammable gases or vapors or combustible dusts
  • Introduction of liquids or gases during employee occupancy
  • Activation of electrical or mechanical equipment during occupancy
  • Slips and falls while entering and exiting the confined space


Air contaminants - Substances in the air which may be harmful to health. Five major types of air contaminants are Dusts, Mists, Fumes, Gases and Vapors.

Atmospheric testing -
The testing of the atmosphere within the confined space with approved test equipment.

Blank -
A solid plate installed through the cross section of a pipe, usually at a flanged connection.
Blind - A blank installed at the end of a pipe, which has at that point been physically disconnected from a piping system.

Breathing apparatus -
Consists of a breathing mask, air supply lines complete with an escape pack, and air tanks that are stored outside the confined space, or self-contained breathing apparatus complete with an alarm.

Combustibles -
Gases contained in the atmosphere that can be ignited given the proper concentration.

Communication -
Continuous contact between a worker in a confined space and a worker outside the confined space whereby the worker outside the confined space is aware of activity by the worker inside the confined space.

Confined space - A space which, because of its construction, location, contents, or work activity therein:

  • Provides limited means of entry or exit
  • Has poor natural ventilation
  • Contains or may develop a dangerous atmosphere
  • may require the use of protective equipment including a capability of immediate rescue of a worker who enters

Enclosed space - Any enclosed area, other than a confined space, in which ordinary job hazards may be intensified.

Hot Work - Any work which produces a source of ignition.

I.D.L.H. - (Immediately Dangerous to Life and Health) A level of exposure to air contaminants which cause a person without respiratory protection to be fatally injured or would cause irreversible and incapacitating effects on that persons health.

L.E.L. -
(Lower Exposure Limit) The concentration of a gas or vapor below which a flame does not occur on contact with a source of ignition.

Lifting device -
A mechanical device designed specifically for the purpose of lifting (removing) workers from confined spaces.

Lock out -
Stopping and securing a machine, process, or system to protect workers from danger due to unexpected start up or the release of hazardous energy.

Operation or repairing equipment -
Includes operation valves or switches, tightening bolts, replacing parts or any operation that includes disturbance of the facilities in the confined space.

Oxygen deficient atmosphere -
An atmosphere where the oxygen content is less than 18 percent.

Oxygen enriched atmosphere -
An atmosphere where the oxygen content is more than 23.5 percent.

P.P.M. -
(Parts Per Million) A unit of measurement that refers to the parts of contaminated material. Often used as a unit with gases or vapors in air. 10,000 P.P.M. equals one percent

Permissible Concentration (P.C.) -
The concentration of an airborne substance to which a worker is permitted to be exposed by regulation.

Purging -
Displacement of an atmosphere in a confined space by a fluid or gas.

Rescue equipment -
Consists of a shoulder lifting harness and a non-combustible, static-resistant lifeline (for lifting).

Respirable (compressed) air -
Compressed breathing air that meets the requirement of CSA Standard CAN 3 Z 180.1 "Compressed Breathing Air", or other standard acceptable to the WCB

Safe atmosphere -
An atmosphere that is free of combustibles, toxic gases, and is not oxygen deficient.

Standby person -
A person trained in emergency procedures and assigned to remain immediately outside a confined space and in communication with the person(s) inside.

Toxic atmosphere - An atmosphere which contains levels of an air contaminant greater than the permissible concentration.

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Confined space:  A space which, because of its construction, location, contents, or work activity therein provides limited means of entry or exit, has poor natural ventilation, contains or may develop a dangerous atmosphere, and may require the use of protective equipment including the capability of immediate rescue of a worker who enters.

Confined spaces are not meant for continuous occupancy, and are likely to be entered only for purposes such as inspection, maintenance or construction. Limited entry and exit points not only make escape or rescue difficult, but also can restrict natural ventilation.

Enclosed space:  A confined space is different from an enclosed space, which is any area enclosed on all sides and overhead, such as a machinery room, storage facility or boiler room, where workers may find ordinary job hazards intensified. Enclosed spaces may be meant for frequent or lengthy human occupancy, and often have accessible points of entry and exit. Requirements for safe entry to enclosed areas are usually less strict than for confined spaces.


All workers who could be exposed to danger in or around confined spaces will wear appropriate personal protective equipment.

Non-respiratory protective equipment:

  • Hard Hats
  • Hearing Protection
  • Industrial Eye and Face Protectors
  • Safety Toed Footwear
  • Gloves
  • Coveralls

Respiratory protective equipment:

Air Purifying - respirators in which contaminated workplace air is drawn through an air-purifying device into a facepiece worn by the worker.

Atmosphere-Supplied - respirators in which non-contaminated air is provided under pressure to the worker.

Safety harness and lifelines:

Each worker who enters a confined space in which either:

  • a harmful atmosphere could affect the ability of the worker to escape with assistance
  • the worker may become entrapped or entangled
  • the descent is in excess of 10 feet

must wear a safety harness attached to a lifeline, which will permit effective rescue and fall arrest protection.

Written work procedures:

Physical Plant will have Written Work Procedures and workers will be trained to follow them. Effective written procedures will:

  • be written in plain language
  • specify who is responsible for the work
  • define or list the confined spaces to which the procedures apply
  • be followed and applied to the specific circumstances of each confined space

Access and egress:

A safety checklist for access points and the standby area outside will address the following safety questions:

  • Are warning signs, barricades or other means of communication provided to prevent inadvertent entry?
    • by workers
    • by students
    • by visitors
  • Are traffic control measures provided where vehicular traffic could present a hazard?
  • Do fixed ladders, up to and into the confined space, conform to standards acceptable to the WCB?
  • Are temporary ladders positioned and secured properly?
  • Is the access port and standby area provided with necessary guardrails and toeboard?
  • Is the standby location of adequate design and area to permit effective rescue?

Entry procedures:

The procedure for entry into a confined space will depend on the following factors:

  • access and egress to the confined space
  • type of work to be completed
  • potential hazard encountered, e.g. combustible gas, oxygen deficiency, etc.
  • proximity of possible backup assistance

Based on these considerations, three types of confined space entries have been defined.

No presence of harmful gases or oxygen deficiency detected. Inspection and maintenance will not cause the release of harmful substances into the confined space.

No presence of harmful gases or oxygen deficiency. The work may cause the release of harmful substances into the confined space.

Presence of harmful gases or oxygen deficiency detected. Ventilation does not guarantee a safe atmosphere. DANGER - NO ENTRY ALLOWED.

The selection of the procedure shall by determined by the supervisor in consultation with the crew, prior to entry into a confined space by a worker.

The entry procedure to be used is dependant upon the situation encountered, and is not an attribute of a specific facility. If for any reason work is halted, such as a coffee or lunch break, re-testing of the atmosphere and re-classification of the entry procedure must be done before resuming work.

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TYPE A - No presence of harmful gases or oxygen deficiency is detected.

Review procedure - Two workers will be required. The supervisor/lead hand shall review the procedure to be followed.

Safe worksite - The worksite shall be made safe in accordance with accepted industry safe work practices and WCB Health and Safety regulations to protect workers from traffic and to protect other employees, students and visitors from any potential danger. Equipment shall be placed for efficient operation and to prevent danger to workers and others. Ignition sources shall be eliminated.

Atmospheric testing - Atmospheric testing shall be completed. Tests shall include combustible gas, oxygen content and hydrogen sulfide (H2S). Results of the testing shall be recorded at the time of testing. Initial testing shall be done just below the confined space cover prior to removal to determine whether an oxygen deficient atmosphere exists or whether combustibles or other harmful substances are contained in the atmosphere. If the atmosphere is deemed to be hazardous, remove the confined space cover and ventilate mechanically for ten minutes. Conduct a re-test. Detection of any level of H2S, or more than 20% L.E.L. of combustible gas reading, or an oxygen level of less than 18%, shall require the use of TYPE C entry procedures. If continuous venting causes the atmosphere in the confined space to clear to less than the limits given in the preceding instruction, use TYPE A procedures.

Entry - One worker shall enter the confined space and the other shall remain at the entrance. Communication between the two workers shall be continuous. Visual checking shall also be continuous if possible.

TYPE B - No presence of gas or oxygen deficiency detected. The work may cause the release of harmful substances into the confined space.

Review procedure - A minimum 3-person crew will be required to perform this procedure in addition to a supervisor who will maintain communication with the crew. The supervisor or crew leader will review the procedures and any special equipment requirements. Responsibility for the work, materials, and equipment will be assigned. competency of the workers to use specialized equipment such as atmospheric testing devices, hoisting equipment, harness and respiratory equipment, shall be confirmed prior to the work commencing. Workers shall have the required up-to-date training for any equipment which they are to use.

Safe worksite - The worksite shall be made safe in accordance with accepted industry safe work practices and WCB Health and Safety regulations to protect workers from traffic and to protect other employees, students, and visitors from any potential danger. Equipment shall be placed for efficient operation, and to prevent danger to workers and others. Ignition sources shall be eliminated.

Atmospheric testing - Initial testing shall be done just below the confined space cover to determine whether an oxygen deficient atmosphere exists or whether other harmful substances are present. Further testing shall be conducted above the floor level, midpoint of the height, and just below the ceiling, by the person entering the confined space. A continuous monitor shall be used in the vicinity of the worker while the work in the confined space is being done. Should the continuous monitor indicate that the atmosphere has become unsafe, the worker(s) shall immediately evacuate the confined space. If the atmosphere can not be made safe by continuous ventilation, no OUC employee shall re-enter the confined space. The appropriate Contractor, Utility (ie: B.C.Gas) or emergency authority shall be called.

Entrance cover - The entrance cover shall be removed in such a manner as to prevent sparks.

Water - Excess water shall be removed from the floor of the confined space prior to work commencing.

Ventilation - The confined space shall be continuously ventilated using approved forced-air ventilation equipment to remove combustible, oxygen deficient or stale air. Ventilation shall be carried out for a minimum of 10 minutes prior to entry and continuously during the work process. Ventilation hoses shall be purged prior to insertion into the confined space. The ventilation hose(s) should be placed to circulate air into the corners of the confined space and to ensure complete ventilation.

Ventilation equipment - Ventilation equipment shall be approved and maintained in good working order. Portable ventilation equipment shall be placed a minimum of 3m from the opening. The intake and exhaust outlet shall be positioned such that the exhaust fumes do not blow into the ventilating air intake. Propane and gasoline powered equipment shall be placed such that spillage will not run into the opening of the confined space.

Workers’ responsibility - The responsibilities of each of the 3 employees involved in a confined space entry for operation and maintenance are as follows:

Employee 1

  • Shall be suitably clothed and shall use all personal protective equipment as required.
  • Shall wear a lifting harness complete with lifeline attached to a lifting device. Shall be responsible for atmospheric testing in accordance with WCB regulations.
  • Shall execute activities in the confined space as directed.
  • Shall determine that the atmosphere is safe prior to Employee 2 and/or other employees entering the confined space.

Employee 2

  • Shall enter the confined space when employee 1 declares it safe to enter or, if it is a one-man job.
  • Shall be in radio communication with Employee 1 and Physical Plant dispatch.
  • Shall be stationed at the entrance to the confined space to maintain communications with Employee 1 and shall maintain visual contact if possible and be prepared to initiate the confined space rescue procedure.
  • Shall be in radio contact with employee/and Physical Plant dispatch.
  • Should the Outside Employee have to initiate the confined space rescue procedure, he/she shall immediately contact Physical Plant Dispatch by two way radio and request on-site first-aid, fire department and ambulance.
  • Shall, with assistance and under the direction of first-aid attendant and/or emergency authority, attempt to retrieve Employee 1 by activating the winch.
  • Shall stand by the confined space entrance at all times.
  • Shall wear suitable clothing.
  • Shall have up-to-date first aid training.

Person in Charge:

  • Shall supervise the work activities and shall be responsible for adherence to all safe work practices and conformance to the entry procedures.
  • Shall be stationed at the winch of the lifting device.
  • Shall tend the winch to assist in lowering or hoisting the entry worker.
  • Shall remain at the hoist at all times. Shall have up-to-date first aid training.
  • Shall maintain two-way radio communication with those in the confined space and physical plant dispatch.
  • Shall request first aid, fire, ambulance and police assistance if an emergency develops.
  • Shall notify the safety office and senior supervisor(s) of the status of the emergency activities.
  • Shall give all possible assistance to the emergency authorities (fire, ambulance, and police).

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Rescue Procedures - Additional Employees:

If more than one entry employee will initially be entering the confined space, one more surface worker will be required to man the hoisting device for each additional entry worker.

Rescue procedures shall come into effect when communications with the person(s) in the confined space cease or when visual checking indicates that the person(s) in the confined space is disabled.

Specific rescue procedures will be prepared prior to any confined space entry and shall follow the general procedures outlined below:

  • The person in charge shall report to Physical Plant dispatch, or other office employees that a confined space rescue procedure is in effect and request additional assistance (first aid, fire, rescue, ambulance).
  • Physical Plant dispatch shall inform the emergency authorities that a "confined space rescue" is needed.
  • The Outside Employee shall commence lifting Employee 1 from the confined space while another Employee attempts to guide Employee 1 (by means of lifeline) through confined space entrance.
  • If the disabled worker can not be removed by the lifting device, the person in charge shall contact Physical Plant Dispatch.
  • Physical Plant Dispatch will contact the emergency authority and upgrade the status.
  • Any other employees who were in the confined space to assist in the rescue shall exit immediately following the rescue. Absolutely no remedial action shall be taken in the confined space.
  • The worksite shall be cleared if the danger continues. The person in charge shall initiate an accident investigation.

TYPE C - Presence of combustible gas, harmful substances or oxygen deficiency is detected. Ventilation does not guarantee a safe atmosphere. DANGER - NO ENTRY ALLOWED.

Review procedure - The supervisor shall assess the situation to determine:

  • Is the work essential? Can it be rescheduled?
  • Is the situation a utility responsibility, ie. natural gas leak? Are emergency authorities required?
  • What special equipment is required?
  • Are the workers to be involved fully trained and competent in the work to be performed?
  • Should a qualified contractor be brought in?

Confined Space Entry Summary:

  • Ensure that all the required safety related equipment is set up and fully operational.
  • The atmospheric testing device is charged, calibrated and fully functional prior to entry.
  • Discuss the entry and rescue techniques. Also discuss the work that is to be done. This will ensure that everyone understands the task and their individual responsibilities.
  • Test before entry. Enter only when you are sure that the atmosphere is safe.
  • Do not trust your senses.
  • Wear and use fall arresting equipment and other P.P.E. where required. Fall arresting equipment must be used when the descent is over 10 feet.
  • Continuously monitor the atmosphere while in the confined space.
  • Immediately leave the confined space when the testing device indicates that a harmful atmosphere is developing or when the tester alarms.
  • Re-test the confined space to ensure that a safe atmosphere exists after coffee breaks, lunch, etc.
  • Mechanically ventilate the confined space for a full 10 minutes prior to, and during entry.

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