Can I run telephone cables and standard UTP CAT5/6 in the same conduit? Will it cause any interference or cross-talk?

3 Answers 3


You can mix UTP cable categories in the same conduit. The real reason not to is that it is harder to maintain because all the cable types exit the same place, and you need to separate them after they exit the conduit.

Be sure to maintain a fill ratio of no more than 40% to allow proper firestopping. There are calculators and tables for the National Electric Code to determine the number of cables you can fit in a particular size conduit to maintain the proper fill ratio.


I believe Cat5 and Cat6 are properly shielded (or can be, guess it depends on what you buy?) where Cat3 is not. You shouldn't experience cross-talk between the cable types.

  • Category cable is specifically UTP (Unshielded Twisted Pair). The immunity from noise is delivered by the cable twists, not shielding.
    – Ron Maupin
    Jul 25, 2017 at 15:16

Yeah, you can use UTP cat5/6 in the conduit. Use one of the existing Cat5/6 cable to carry the audio to the speakers in various locations throughout the house. So in this case, the very same cable that's carrying ethernet is carrying amplified audio. The cross-talk would not happen.

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