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I’ve been reading about the right way to install Ethernet cable at home (1) (2) (3) (4) and my requirements are:

  • Category 6A cable for future-proofing (as of 2019, this seems better than Cat 6).
  • Shielded F/UTP cable for robustness to EMI/Radio Frequency Interference. (5)

I have a run in the basement that would be above a drop ceiling, but the drop ceiling is not currently used as a plenum space— as far as I know. There are returns and supplies that are ducted to the finished basement, but they appear to be sealed. This home is located in the USA.

Question 1: Plenum Fail

Some of the articles here and on Wikipedia make it sound as though you need to plan for space above dropped ceiling to be Plenum in the event of a ducting failure or if something gets disconnected in the future.

This would push me to 6A-FUTP-CMP which is pretty expensive cable (let’s say $4-600 per roll) and hard to find besides. Is this warranted: do you need to treat above-the-dropped-ceiling space as potential plenum space, or only if you know it is a plenum?

Question 2: Unfinished Portion Basement

If I run cabling in the unfinished portion of the basement, do I need to use CMP grade cable just in case a future renovation adds a ceiling that would invalidate the cable?

Or do I expect that a future renovator (me) would locate all the cable that’s about to be covered up and rip it out and replace it? Or is this moot because single-family home basements typically don’t use drop ceilings as plenums and you don’t have to treat them that way?

  • Where are you located in the world? – Ed Beal Oct 21 at 4:03
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    If it is cheaper, U/UTP is likely fine in domestic. It's not so good when you have bundles of several cables tied fairly tightly and alien crosstalk becomes an issue, like in commercial. – Someone Somewhere Oct 21 at 6:50
  • In the U. S. A. Question updated, thank you! – whiskeychief Oct 21 at 10:05
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The purpose of plenum rating is that if the wire is overheated (e.g. from fire), it won't emit chemicals which will blind, stupefy, poison, or incapacitate people trying to escape from aforementioned fire. This matters in spaces where air is handled.

Maybe a drop ceiling won't be air handling space unless a duct is damaged, but consider the probability of the duct damage and the overheating of the wire being caused by the same event.

  • Good thoughts. I’ll go ahead and get Plenum then. It’s not that much more money in bulk (especially with my free labor to install). – whiskeychief Oct 22 at 14:12

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