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Wednesday, February 15, 2023
Question:
Hello CQD, with the increased use of network connected equipment, the demand for network cabling installations is higher than ever. Does the NEC® have rules restricting how many CAT 6 cables can be installed in a conduit? Thanks, Samuel Noren
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Answer:
Hi Samuel, great question. Yes, the NEC® does indeed provide guidelines for installing cables in conduits and raceways. Assuming that the “conduit” you are referring to in the question is EMT, Section 358.22 provides the general rule for EMT fill. This Section points to Chapter 9 for conductor/cable and fill. Table 1 establishes the maximum cross-sectional area that can be filled for conduit or tubing based on the number of conductors or cables installed:
- 1 Cable – 53%
- 2 Cables – 31%
- Over 2 – 40%
Assuming there will be more than two (2) CAT 6 cables installed, the EMT could be filled up to 40% of the EMT cross-sectional area.
The area of CAT 6 cable is not provided in the Tables in the NEC®. The Table Note (5) states when the area of conductors or cables are not included in the Chapter 9 Tables, the actual size of the conductor or cable shall be used. The actual size of a CAT 6 cable can be found in the manufacturer’s literature or on their website.
Another consideration is also Section and Table 725.144 which provides additional requirements for the transmission of power and data on the same cable or PoE. When a data cable will also be transmitting power, there are bundling limitations to prevent excessive heat.