Comparing Cable Options
The options available for different cable products these days are very abundant. Everyday new options are being introduced into the electrical market. Whether it be from the specifications changing to the different variations, the choices are becoming more and more plentiful as time goes on. One option; however, which is usually the first thing a person takes into consideration when purchasing cable remains pretty constant. This is whether or not the cable to be used will need to be plenum rated or Non-Plenum rated. When we refer to cable as plenum or non-plenum we are not talking about the cable itself. The plenum rating that we are talking about actually refers to the jacket that surrounds the cable.
This is an important issue related to the chemical composition of the cable and your building‘s construction, especially when it comes to your small business phone system and low voltage data/audio cabling.
There are two basic types 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.
Plenum-rated cable actually received this name from an old HVAC term referring to “Plenum spaces”. A “plenum space” is the part of a building that enables air circulation by providing pathways for heated/conditioned and return airflows at a higher pressure than normal. Typically, spaces between the structural floor or a dropped ceiling are considered plenum. Some drop ceilings are actually designed tight enough to where air circulation is restricted and may be considered a non-plenum area. A lot of times when conduit is not installed, plenum cable is required because the cable is “freely installed”