We are building a new house and I plan to run a Fiber Patch Cable - LC to LC OM3 10Gb/Gigabit from the server room to the office. The low voltage person suggest that I get something that is CMR or FT4 rated?!

I looked but I couldn't find more information on this. I can find details for ethernet but not fiber. Is this even a thing? I was looking at this https://www.amazon.ca/gp/product/B01C5HH6IO/ref=ppx_yo_dt_b_asin_title_o01_s02?ie=UTF8&th=1 will it work.


  • For a home, copper is definitely easier to work with and is capable of 10Gbps. You can buy SFP+ to RJ-45 transceivers that will use 10Gbps over CAT6/CAT6a or greater. – Sam Forbis Aug 6 '20 at 14:34

CMR refers to a communications cable meeting the UL 1666 flame test. CMR is a type that must include conductors, so normal fiber optic cable would be a different type, OFNR.

FT4 refers to the flame test defined by UL 1685/IEEE 1202. The FT4 flame test is less stringent than that defined by UL 1666, so any product meeting the UL 1666 flame test would also pass the FT4 flame test.

The product you linked to mentions UL 910, which is a historical reference to the plenum flame test now defined by NFPA 262. This flame test is even stricter than UL 1666, so this product would certainly meet the UL 1666 and FT4 flame tests. Fiber optic cable meeting the plenum flame test would be referred to as OFNP.

  • 1
    Ah man - thank you for such a well constructed response! – pookieman Aug 7 '20 at 4:11

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