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Can I-Line busway be installed in a plenum?

Assembly/Installation, Application

Product Line:

UL 857, CSA C22.2 No. 27-1973, NFPA 70 Art. 368

Space restrictions in building construction can drive the desire to locate busway in extraordinary locations.

Article 368.10 paragraph B of the National Electrical Code applies:
(B) Behind Access Panels.   Busways shall be permitted to be installed behind access panels, provided the busways are totally enclosed, of non ventilating-type construction, and installed so that the joints between sections and at fittings are accessible for maintenance purposes. Where installed behind access panels, means of access shall be provided, and either of the following conditions shall be met:
  • (1)  The space behind the access panels shall not be used for air-handling purposes.
  • (2)  Where the space behind the access panels is used for environmental air, other than ducts and plenums, there shall be no provisions for plug-in connections, and the conductors shall be insulated.
We do not recommend installation of busway product in any plenum used for environmental air, as a failure of the product would typically release smoke and gases, and this is not something desirable in an HVAC system. 

Also, please consult the local authority having jurisdiction on this issue.
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