National Electric Code Compliance when Installing Wi-Fi and
Wireless Networks in the Above Ceiling (Plenum) Space
Cabling and Wireless Installation Articles 1-28-2014
Facilities operators, particularly in hospitals, schools, government and other public
buildings, are strict adherents to the National Fire Protection Association’s National
Electric Code (N.E.C). Data network installers are keenly aware of the N.E.C. due to
the requirements for type and rating of cabling, fire-stopping, grounding, wire trays,
etc. Of particular concern is installation of cabling in the air-handling or plenum
space. Due to the critical role of the air-handling space in fire and smoke suppression
and containment, installers are diligent in N.E.C. compliance, and Authorities Having
Jurisdiction (AHJs) are aggressive in enforcement of the code.
Although it may be counter-intuitive, wireless infrastructure often requires installation of more horizontal cabling. By virtue of the fact that the ideal location for
wireless access points and antennas is in the ceiling, horizontal cabling is generally
run through the above ceiling (plenum) space. Additionally, the access point itself
may be installed in, or above, the suspended ceiling, requiring consideration of N.E.C.
requirements related to equipment installation in the ceiling.
Oberon’s Model 1052 series ceiling wireless enclosures can simplify compliance with
National Electric Code. Specify products which are UL listed, and constructed of steel
and UL specified plastics to maintain the ceiling systems burn rating.
Copyright 4-28-2012
www.oberonwireless.com
The NFPA updates the N.E.C. every two years. In prior years, there has been
confusion related to the definition of “plenum” space, and what was permitted, and
prohibited, in the “plenum” space. The 2011 N.E.C. reconciles the terms “plenum”
and “air-handling space” as follows:
- Article 300.22(C) “Other Spaces Used for Environmental Air (Plenums). This
section shall apply to spaces not specifically fabricated for environmental airhandling purposes but used for air handling purposes as a plenum.
- Article 300.22(C) Informational note 1 “The space over a hung ceiling used
for environmental air-handling purposes is an example of the type of other space
to which this section applies
In essence, the N.E.C. is saying that (in most cases) “plenum” space and “airhandling” space is the same thing: the space above the suspended ceiling where
cabling is run and wireless access points are often installed. Furthermore, the NEC
states the following:
- Article 300.22(C)(3) “Electrical equipment with a metal enclosure, or
electrical equipment with a nonmetallic enclosure listed for use within an airhandling space……. shall be permitted to be installed in such other space unless
prohibited elsewhere in this Code
- Article 300.23 “cables, race-ways and equipment installed behind panels,
including suspended ceiling tiles, shall be arranged and secured so as to allow
removal of panels and access to the equipment.”
When installing wireless access points and networking equipment in the above ceiling
(plenum) space, the installer should verify the following:
1. There should be no “non-plenum rated” equipment or cabling in, or above,
the ceiling, unless it is within a metal enclosure
2. There should be no unfilled penetrations in the ceiling
3. The metal enclosure shall have a solid, non-ventilated back box to retain the
2 or 4 hour burn rating of the ceiling system, and to act as a barrier to the
spread of smoke
4. The metal enclosure shall include a UL listed fire stop to fill in the openings for
cable egress
5. The enclosure shall be supported by the building structure, independent of the
suspended ceiling grid work
6. The enclosure should permit secured access to the equipment inside
Oberon’s UL listed, metal ceiling enclosures provide the confidence that the
installation is compliant with N.E.C. 2011 requirements for installation in the above
ceiling space (plenum) space, and will satisfy even the strictest local and regional
code enforcement authorities, regardless of whether AC line power, or Power over
Ethernet (PoE), is used to power the electronics. Certain models feature UL 94-5VA
classified, impact resistant ABS domes. This is the highest rated plastic for fire
resistance, and is essential for the UL listing of the product. Oberon’s ceiling
enclosures all include a fire stop foam cable egress kit.
Additional information on wireless network infrastructure is available at:
http://www.oberonwireless.com/faq-resources.php
Copyright 4-28-2012
www.oberonwireless.com