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BCC Ruling No. 95-54-474

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IN THE MATTER OF Subsection 24(1) of the Building Code Act, 1992.

AND IN THE MATTER OF Article of the Revised Regulation of Ontario 1990, Regulation 61, as amended by O.Regs. 400/91, 158/93, 160/93, 355/94 and 20/95 (the "Building Code").

AND IN THE MATTER OF an application by Mr. Peter brown, Project Manager of Pratt & Whitney Canada Inc. for the resolution of a dispute with Mr. Agris Robeznieks, Chief Building Official, City of Mississauga, concerning whether the FT4 cables and smoke detectors that would shut down the HVAC units installed within the air-return plenum space in an office extension in lieu of FT6 cables will provide sufficiency of compliance with Article of the Building Code, at Pratt & Whitney, Mississauga Plant, 1801 Courtney Park Drive, Mississauga, Ontario.


Mr. Peter Brown
Pratt & Whitney Canada Inc.
Longueuil, Quebec


Mr. Agris Robeznieks
Chief Building Official
City of Mississauga


Mr. Roy Philippe, Chair
Mr. Demir Delen
Mr. Rick Florio


Toronto, Ontario


November 14th, 1995


Mr. Leszek Muniak, Principal
Larden Muniak Consulting Inc.
Toronto, Ontario
For the Applicant

Mr. Barclay Steen
Manager of Mechanical Engineering & Inspection
City of Mississauga
For the Respondent


  1. The Applicant

Mr. Peter Brown, Pratt & Whitney Canada Inc., is the holder of a permit under the Building Code Act, 1992 to construct an addition to an existing second floor office space at Pratt & Whitney, Mississauga Plant, 1801 Courtney Park Drive, Ontario.

  1. Description of Constrution

The subject building functions as a manufacturing, assembly and testing repair facility for aircraft engines and components. It is classified as a Group F, Division 2 major occupancy. The building is a two storey, fully sprinklered structure, facing 3 streets.

At the east end of the manufacturing plant exists an office space that has undergone an expansion. Additional area has been added to the second floor of the office space.

The ceiling return-air plenum system in the new expansion space has been equipped with FT4 cable.

The office expansion area has 3 HVAC units which re-circulate air within its own confined space. Air is not re-circulated beyond the smoke compartment.

  1. Dispute

The dispute between the Applicant and Respondent concerns sufficiency of compliance with the technical requirements of Article of the Building Code. At issue is whether FT4 cables and smoke detectors that would shut down the HVAC units may be installed within the air-return plenum space in the office extension in lieu of FT6 cables.

  1. Provision of the Building Code

Article Plenum Requirements

  1. The concealed space between the ceiling and floor or ceiling and roof used as a plenum need not conform to Sentence and Article provided

    1. all materials within the ceiling space have a flame- spread rating of not more than 25 and a smoke developed classification of not more than 50, except for

i. tubing for pneumatic controls,

ii. ptical fibre cables and electrical wires and cables that exhibit a flame-spread of not more than 1.5m (4 ft 11 in), a smoke density of not more than 0.5 at peak optical density and a smoke density not more than 0.15 at average optical density when tested in conformance with the Flame and Smoke Test in the Appendix to CSA C22.2 No. 0.3, "Test Methods for Electrical Wires and Cables" (FT6 Rating),

iii. optical fibre cables and electrical wires and cables that are located in totally enclosed noncombustible race-ways, and

iv. single conductor electrical wires and cables that exhibit a vertical char of not more than 1.5 m (4 ft 11 in) when tested in conformance with the Vertical Flame Test - Cables in Cabletrough in Clause 4.11.4. of CSA C22.2 No. 0.3, "Test Methods for Electrical Wires and Cables" (FT4 Rating), and

    1. the supports for the ceiling membrane are of noncombustible material having a melting point not below 7600C (14000F).

  1. When the concealed space referred to in Sentence (1) is used as a return-air plenum and incorporates a ceiling membrane that forms part of the required fire-resistance rating of the assembly, every opening through the membrane shall be protected by a fire stop flap which shall

  1. stop the flow of air into the concealed space in the event of a fire,
  2. be supported in a manner that will maintain the integrity of the ceiling membrane for the duration of time required to provide the required fire-resistance rating, and

  1. conform to CAN4-S112.2-M, "Standard Method of Fire Test of Ceiling Firestop Flap Assemblies".

  1. Asbestos paper shall not be exposed in supply and return-air systems.

  1. Applicant's Position

The Applicant submitted that sufficiency of compliance would be achieved as follows:

  • smoke detectors would be installed within the plenum space for each of the three HVAC units; and,

  • the HVAC units will be interconnected, therefore, the shut down of one will cause all systems to shut down. Once a smoke detector is activated, the air system no longer functions as a return-air plenum.

The Applicant also submitted that the Building Code would permit an FT4 classification of cable in a ceiling space which is not used as a return-air plenum

  1. Chief Building Official's Position

The Respondent submitted that a second storey office addition has been constructed over an existing shop area which has also been renovated to create office space. FT4 cables have been installed in the ceiling spaces of both storeys which are used as return air plenums.

The Respondent submitted that Article of the Building Code allows only single conductor wires and cable to have an FT4 rating. All other exposed cables require an FT6 rating.

The Respondent submitted that there is approximately 100,000 lineal feet of FT4 cable installed at this project contrary to Article The Building Code does not provide for the installation of smoke detectors as an alternate to FT6 rated cable.

  1. Commission Ruling:

It is the decision of the Building Code Commission that the installation of FT4 cable in the plenum space provides sufficiency of compliance with Article of the Building Code provided duct type smoke detectors connected to the fire alarm system are installed within the return air space which will shut down all the H.V.A.C. units within the second floor addition on activation.

  1. Reasons:

i. The air handling system serves only the second floor addition.

ii. The building is sprinklered.

iii. Evidence indicates only 25% of the communications cable are not enclosed in a conduit or metallic raceway.

Dated at Toronto, this 14th day, in the month of November, in the year 1995, for application number 1995-63.

Roy Philippe

Demir Delen

Rick Florio