Feb 1, 2002 12:00 PM
What's with Plenum?
[In reference to Steve Filippini's column, “Defensive Strategies,” in the October 2001 issue,] it seems to me the jacket on plenum wire tears more easily. Also, I thought plenum was used for the non-toxic rating that designers look for, not for fire resistance.
The author responds:
Plenum cable was designed for use in the plenum spaces of a building. This plenum space is used for air circulation in heating and air conditioning and is also used as a way to route telephone and low-voltage communication cables throughout a building. Plenum cable has an additional fire-resistant coating (Teflon is one common example) that slows down the rate at which the cable will burn. This coating does not give off toxic fumes as it burns, which is what you need in areas of air circulation. The outside jacket of plenum cable is typically rugged, quite durable, and will withstand common tears and splitting. What has occurred in some installations is that the cable loops and twists as it is pulled, causing tension on the jacket when the loop tightens. As the tension mounts, the harder outside jacket won't give as easily as soft rubber insulation, and it will split. As with any wire installation, proper pulling and unspooling techniques need to be used to avoid cable damage.
Thanks to Kruglak
I found the timing of the December 2000 “Feedback Forum” ironic. Just last week, I won a bid by offering a project discount to lower the overall price without compromising my normal pricing. I had planned to e-mail you with my success story when I read the disbeliever in your letters column. Thanks for the good advice; and thanks for the advice last year to raise my hourly service rate. Not only did I not hear a single negative comment from any client, I also [quickly] recovered the cost of [Alan Kruglak's] book that I purchased. Talk about quick return on investment!
Harvey Electric and Sound
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