When & Why do I Need Plenum Rated Cable

When & Why do I Need Plenum Rated Cable

This is an important issue related to the chemical composition of cable and your building’s construction.

There are two basic type of building construction as it regards the movement of heating, air conditioning and ventilation through office buildings.  In newer construction and in most high rise construction the architects save space and the cost of expensive sheet metal return air ducts by simply drawing the air back to the heating/air condition unit through the open spaces above the ceiling and between the walls.

Now, let’s discuss the basis of the problem.  Standard cable is jacketed in PVC (Polyvinyl Chloride), with the Chloride element causing the trouble.  When PVC burns or smolders it releases toxic fumes into the air (Hydrocloric Acid and Dioxin).  A plenum air return would unknowingly circulate toxic air throughout an office.

Since both you and the Fire Department don’t want you to die from breathing in toxic fumes from your cabling, code requires Plenum Rated cable installed through any plenum air return space.  Our Installation Team is required run Plenum Rated cable if they determine the air space in not ducted.

How do I determine if my building uses Plenum Air Return? 

  1. If you have a large wall or ceiling return air grate; remove and see if there the air is channeled through sheet metal ducting.  If there is no sheet metal duct;  just the open ceiling or wall space, then you are required by law to use Plenum Rated cable.
  2. If there is no wall or ceiling return air grate; look closely at your fluorescent lighting fixtures to see if there is a gap around the edge of the fixtures and put your hand over the gap and you can feel air movement.  Obviously your air conditioner should be running at the time!  The lack of wall or ceiling return air grates is usually a sure sign that you require Plenum Rated Cable.
  3. Computer Rooms typically use a raised flooring system for the server racks.  This allows intensive cooling to be pumped through the space under the floor to cool the servers, switches, routers, etc.  Cabling between the many devices and to the users runs through this open floor space.  This by definition is a Plenum Air space and requires Plenum Rated Cable.

Now you know the whole story!

If you still have questions, give us a call at 800-390-1200.


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