I'm looking to install POE security cameras. Due to the long runs outdoors the cable needs to be UV resistant. This usually means that cable has to have a sheath that is unrated (CMX) and can't be run for long distances inside a structure. NEC allows for 50 feet indoors provided its terminated inside an "enclosure" or "primary protector".

enter image description here


I believe the logic behind this all comes down to fire. If lighting or a large voltage is applied to the exterior of cable it could ignite the sheath and start a fire inside the home. However, I don't know how i'm able to reasonably terminate multiple runs coming into a structure from various sides/distances all in enclosures grounded enclosures.

In my state that involves a low voltage 06 licence which means your basically an electrician. 4000 hours apprenticeship + certs, licence, bond all of it.

This could get pretty expensive and is well beyond the scope of what most home owners are expecting for security camera installs.

That said, I want to do these jobs right and was wondering what common practice is here.


1 Answer 1


Type CMX is not "unrated", so that Code section does not apply

Your confusion here stems from a misunderstanding of what the Code means by an "unrated" communications cable. You seem to be under the impression that it's referring to all communications cables that do not have a special rating (such as plenum or riser), but that's not the case. Instead, an "unrated" cable has no NRTL listing or associated labeling/markings whatsoever, which means that it is not assigned a type for NEC purposes, and is restricted in its use within structures by the Code section you cited. These cables are used by telephone utilities for service drops because the utility has its own specifications (Telcordia/Bellcore and so on) for cabling plant and doesn't want to spend the extra time and money making utility cable makers get NRTL listings to prove that the cable has properties the utility is already satisfied about.

Instead, the permitted usage of your type CMX cable is governed by NEC 800.113(L), which permits permits the use of any length of type CMX cable less than ¼" in diameter within a one or two-family dwelling. If your cable is too fat to fall under that rule, you can sleeve it in any Chapter 3 raceway in order to comply with the NEC. (ENT aka "smurf tube" is the cheapest and easiest choice for this.)

  • 1
    I fully agree and know of no requirement even in my state that licenses most everything except communications cables for residential buildings below 3 stories above grade. +
    – Ed Beal
    May 30, 2020 at 1:25
  • 2
    Thank you for the response. This was really helpful. I mistook CMX for unlisted because a cable vendor insisted it was the case. It looks like the 2020 NEC has removed the term CMX and replaced it with "limited use cables". Is that the same thing? Also, it look like in buildings that are not dwellings you are only allowed 10 feet of exposed length in a non-concealed space. So, if this were a commercial building, how would i get the cable in from the outside through the wall? Does the wall itself count as a concealed space?
    – Cggart
    May 30, 2020 at 7:02
  • @Cggart -- I suspect "limited use" is indeed the same as CMX, and in a commercial space, you'd use a Chapter 3 raceway (conduit) for the job, such as the "smurf tube" I mention in my post May 30, 2020 at 14:55
  • @ThreePhaseEel — Thanks so much for the information. Typically, with POE camera installations, we drill a hole through an exterior wall and place bushings (grommets) around the wire on either side of the wall. The wire runs wild through the hole (perpindicular to the wall itself). This is the way I've always seen it done on smaller jobs. However, the wall interior is an "concealed space" (even though we are only running through 4-6 inches of it. Is this a violation? Does it not count if we are running perpendicular through the wall?
    – Cggart
    May 31, 2020 at 17:38
  • @Cggart -- do you have some local code amendments that further restrict how communications-type (LV) cables can be run? I don't see how what you're describing could ever be a violation of the NEC, provided the cable meets the correct rating criteria.... May 31, 2020 at 17:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.