an onsite picture of a SITA employee carrying a white tube under his arm and checking plans on his tablet phone

March 25, 2019

Balancers are sometimes required to perform TAB work in confined spaces. A confined space is one that has a limited means of entry and/or exit, is large enough for a worker to enter, and is not intended for regular/continuous occupancy. Examples of confined spaces include steam or equipment pits, equipment enclosures (built-up air handling units), equipment mezzanines or interstitial areas and underground vaults.

The Occupational Safety & Health Administration (OSHA) categorizes areas of confined space as either construction work or general industry work. Confined spaces are then defined further as either a “permit-required confined space” or a “confined space.” Typically, for confined spaces identified as general industry work, the safety procedures and permit requirements are already defined by the owner.

This isn’t the case for construction work, which must be evaluated on a project-by-project basis.

An employer (TAB Agency) whose workers (TAB Technicians) are engaged in either construction or general industry work must comply with OSHA Requirements CFR Title 29, Labor, Part 1926, revised July 1, 2015 for confined space work.

Permit-Required Confined Space

A permit-required confined space (permit space) means a confined space that has one or more or the following characteristics:

  1. The space has a potentially hazardous atmosphere.
  2. Contains a material that has the potential for engulfing an entrant.
  3. Has an internal configuration (piping, conduit, ductwork, etc.) such that an entrant could be trapped or asphyxiated.
  4. Contains other recognized serious safety or health hazards.

OSHA requirements make the “controlling contractor” (usually the general contractor) in construction work the primary point of contact for information about permit spaces at the job site.

The “host employer” (usually the owner/government) must provide information it has about permit spaces at the work site to the controlling contractor, who passes it on to the “employers” (TAB subcontractor) whose “employees” (TAB Technicians) will enter the space.

The controlling contractor is also responsible for making sure employers outside a space know not to create hazards in the space — such as motor-driven generators placed at the entry of a confined space — and that other employers working in a confined space at the same time do not create hazards for other workers.

Before employers can work at a construction site, each employer must ensure that a competent person identifies all confined spaces where one or more of their employees may work, and identifies each space that is a permit space,

through consideration and evaluation of the elements of that space, including testing as necessary.

Only workers who have been assigned and trained to work in a permit space may do so. Before workers can enter a permit space, the employer must write a permit that specifies the safety measures that must be taken and who can go in.

Typically, the host employer or controlling contractor sets the training requirements for entrants. Training requirements can range from a minimum of a 10 hours to a maximum 30 hours OSHA classes. Two online sources for this training are and

The confined space permit should identify the project supervisor, number of entrants, and any specialized training required. The permit shall include site location, purpose of entry and estimated duration of occupancy.

Communication and rescue procedures should also be identified as well as any special safety equipment including ventilation air, body harnesses, winches, protective clothing, fire extinguishers, etc.

Air monitoring for hazardous gases may be required depending on site conditions. The following gases are typically monitored before and during entry along with the lower flammable limit:

  • Percent oxygen
  • Carbon monoxide
  • Aromatic hydrocarbon
  • Hydrogen cyanide
  • Hydrogen sulfide
  • Sulfur dioxide
  • Ammonia

OSHA has regulations as to the acceptable level and duration of exposure to these gases.

A safety standby person (attendant) is required for all confined space work. The attendant responsibilities include:

  1. Must be familiar with the hazards that may be faced during entry.
  2. Communicates with the authorized entrant.
  3. Assesses activities and conditions inside and outside the space.
  4. Summons rescue and other emergency services as required.

Case Study – “Permit-Required Confined Space” This project involved balancing manual circuit setters on condenser well field loops for a geothermal heat pump system. The well field loops were manifolded in underground vaults. There were five vaults with as many as 30 well loops tied into the manifold for each vault.

The vaults were concrete construction, 6 ft. in diameter, horizontally installed with two 30 in. manholes on either end. There were no ladders, lights or sump pumps installed in the vaults.

The vault and well field plans were shown on the civil site construction plans with no coordination between the civil and mechanical plans. Balancing of the well field vaults was not included in the TAB scope or specifications.

At the completion of construction of the well fields, vaults, and condenser water system piping into the building, we were asked to provide a change order price by the well field contractor to balance the circuit setters inside the vaults.

After much discussion, it was agreed that the vaults were a “permit required” confined space. The permit procedures requirements were written by the general contractor and were made part of the change order documents for pricing.

The entry permit required gas test monitoring prior to — and during — entry, ventilation, lighting, rescue retrieval (harness and winch), two-way communication, an attendant, and 10 hours of OSHA training in confined spaces for the entrant.

An equipment rental package was put together and priced by a local rental company. The rental package included a gasdriven generator, ventilation fan and flexible duct, gas tester, retrieval winch and body harness. Cost was approximately $750/week. When the rental equipment was delivered to the jobsite, it was noted that the gas detector was not in calibration which delayed the project three weeks while waiting for calibration.

After the vault proved negative for hazardous gases, initial entry into the vault indicated 12 to 15 in. of water in the bottom of the vault. Additional time was lost waiting for the water in the vault to be pumped out. Our balancing production time was almost double the amount of time to balance the same number of circuit setters in a normal mechanical room. There was also the additional cost of an attendant.

Case Study – “Confined Space”

This project involved balancing existing VAV boxes where the controllers were replaced with new ones. The facility was a research lab and the VAV boxes were in an interstitial space between floors. The building had three floors with three wings per floor. The interstitial space was also open between wings. The building was of sufficient size such that there was no clear

line of sight from one side of the building to the other or from one wing to the next. The areas were dimly lit and there were no exit signs on the perimeter walls. Due to the high concentration of piping, conduits, ductwork and equipment, there was no cell phone coverage.

This space was considered a confined space but did not meet the requirements for a permit-required confined space because it was ventilated and had no known source of hazardous materials. However, safety protocols were needed for technicians working in the space. An overview of the safety protocols are as follows:

  1. All technicians had to sign-in and sign-out with the general contractor to enter or exit the space on a daily basis.
  2. All work had to be done with a two-man crew.
  3. Each technician was required to have two sources of battery-powered lights (usually a head-lamp attached to the hard hat and a hand-held light).
  4. Two-way radio communication was required between the two technicians.
  5. It was established that the fastest and safest way to exit the space was to find the nearest perimeter wall and follow the wall to the nearest exit. This could take up to 20 minutes depending on your location in the space.
  6. A “point of rescue” was established at each exit door on each wing in the interstitial space.


Confined spaces are not easily identified by a plan review, especially permit-required confined spaces. TAB technicians need to be trained and have the proper safety equipment to enter and work in a confined space. Additional planning, manpower, and equipment are required. Production rates should be adjusted accordingly.

If for any reason you think your work area has a confined space, a Request for Information (RFI) should be written and sent to the host or controlling contractor to identify the area.

If confined spaces are not noted, you should quantify your bid and state that no additional time or expense has been included in your price for working in a confined space. On existing facilities, if possible, attend a pre-bid meeting at the facility to identify any confined spaces and work conditions.