Code permit low voltage cables resting on flat roof?

matt810

New User
Location
Hartland, MI
Occupation
Technical Integrator
Hello: I have an installation where I need to add some IP cameras that use Cat 5e cables to the exterior of a commercial building with a flat roof. It would be much easier to just lay the outdoor rated cat5 on the flat tar roof, and bring all the cables to a central point in the rear of the building and have them enter in one place. Can anyone think of any building or electrical code that would prohibit this? Or even just a general safety opinion. I do wonder if it might be a trip hazzard - though they will be lose enough that they should not really grab your leg if you didn't see them but got underneath one. The other concern I have is if each one would have to be grounded in some way. Thanks!
 

egnlsn

Senior Member
Location
Herriman, UT
Occupation
A/V/Security Technician
Hello: I have an installation where I need to add some IP cameras that use Cat 5e cables to the exterior of a commercial building with a flat roof. It would be much easier to just lay the outdoor rated cat5 on the flat tar roof, and bring all the cables to a central point in the rear of the building and have them enter in one place. Can anyone think of any building or electrical code that would prohibit this? Or even just a general safety opinion. I do wonder if it might be a trip hazzard - though they will be lose enough that they should not really grab your leg if you didn't see them but got underneath one. The other concern I have is if each one would have to be grounded in some way. Thanks!
Put them in conduit (UV resistant PVC) to protect the cables from sun exposure, and weather in general. Sun, snow and ice wreaks havoc on cable.
 

tom baker

First Chief Moderator
Staff member
There are NEC rules on cat 5e cables for lightning protection when the cables are outside
And I agree this is not a really great installation method, esp if for security cameras. Even if the cables are rated for outdoor use, weather conditions will eventually damage the cables. And what will happen when the roof is repaired
PVC is a poor choice as it will expand and contract and not do well. EMT is a better choice.
For your grounding question, look at Art 725, these are probably Class 2 systems if its a IP application, so you should be familiar with those rules.
 

cabledawg

Member
Location
Boise, Idaho
Occupation
cable dude
There are NEC rules on cat 5e cables for lightning protection when the cables are outside
And I agree this is not a really great installation method, esp if for security cameras. Even if the cables are rated for outdoor use, weather conditions will eventually damage the cables. And what will happen when the roof is repaired
PVC is a poor choice as it will expand and contract and not do well. EMT is a better choice.
For your grounding question, look at Art 725, these are probably Class 2 systems if its a IP application, so you should be familiar with those rules.
Roger that...Will be more specific nexttime. And thank you very much. Wished I would of remembered this website sooner :)
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
There are NEC rules on cat 5e cables for lightning protection when the cables are outside... For your grounding question, look at Art 725, these are probably Class 2 systems if its a IP application, so you should be familiar with those rules.
I disagree. (I even looked at the 2017 Code after having to figure out where the OP is and what code Idaho is on because nobody gives that information anymore). Anyway, you wont find anything in 725 regarding grounding. That would be in Art 800, 810 and 820.

A protector is only required when a cable enters a building from either another building, outside plant or an antenna structure. A cable originating in a building and running around on the outside (roof or not) is not considered in that category. That's not to say that a protector wouldn't be prudent though.

Since you may be using POE look at Art 840 starting with 840.160. 840.180 talks about grounding if required.

IMO the proper way to do this is to run your cables inside then "pop" out where the cameras are located. Of course I have no idea what this job looks like.

-Hal
 
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