When to use plenum cable?
It's one of the most common questions in the cabling industry and unfortunately there isn't a simple answer.
To know when a job requires plenum cable instead of riser-rated (also known as PVC cable), the first thing to understand is the difference between the two. In the simplest terms, the difference is in the construction jacket that goes around the copper wires. Riser-rated or PVC Cable (which stands for Poly Vinyl Chloride) is made from a compound of plastics that will release toxic fumes if they catch fire, while a Plenum (sometimes called Teflon or FEP) cable has a jacket made from a plastic compound that won't release toxic fumes when burned. While there is virtually no difference in the electrical properties of say a Cat 5E Plenum and a Cat 5E PVC cable, there is a substantial difference in the cost, with plenum cables usually costing twice as much.
So why would anyone need a plenum cable?
The reason is safety.
If a non-plenum or riser-rated pvc cable (or more likely a bundle of cables) caught fire and released the fumes into the ventilation system within a commercial building, the fumes would affect the entire building. So the basic rule of thumb is that any cable that is going above a drop-ceiling, under a raised floor or into any plenum space (defined as - any part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows) requires a plenum cable.
Sounds simple, right?
It's not.
One reason is that different municipalities can have different fire codes. Some cities or counties require plenum cable in all commercial buildings and if the local fire inspector finds PVC-rated cable in a plenum-designated area, the contractor will likely be required to tear it out and replace it at his expense.
Also, some places, require that all cable be run through pipe, which means that any fumes would stay in the pipe and therefore not reach the ventilation system, so PVC cable is perfectly acceptable.
Additionally, plenum cable is rarely required for residential applications, so if your wiring a home office go ahead and save yourself some money by going with a PVC Jacket. However, on the commercial side of the business, you are always safe by installing plenum cable. It costs a little more, but you'll sleep easier knowing that you won't have to tear it out!
For more questions about low-voltage cabling or for pricing on cable and connectivity products, contact Diversified Wire & Cable at http://www.dw-conline.com
Article Source: http://EzineArticles.com/?expert=Todd_F_Lorenz
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