atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring strain relief

but unless it is CM or better it is a violation of 800.154(C)(3). In this application, CMX will not cut it in lengths >10'.

That doesn't apply to wiring that is not premises wiring within or attached to the structure. This would actually be considered a patch cord. SO cord is not riser rated.

-Hal

Hal,
Can you cite the NFPA 70 section that gives the OK to installing any type of communications cable in a commercial building if it's not rated at least CMX? The only case I can think of is when an OSP cable enters a building and then is subject to the "50-foot rule". As far as I know, SO cord isn't generally considered to be a communications cable, so I don't see the correlation.

Can you cite the NFPA 70 section that gives the OK to installing any type of communications cable in a commercial building if it's not rated at least CMX?

No, and you won't find too many places where the NEC says anything is OK. If something is not prohibited then it must be OK. That's the way the book is written and should be interpreted.

A patch cable that extends from a wall jack to a PC is not considered premises wiring and does not have to be listed as anything. NFPA 70 only covers LV wiring installed within the building structure- IE- floors, walls and ceilings. With few exceptions, wiring what is run outside of the building both aerially or buried or wiring used to connect equipment to a jack (as long as it is not fastened in place) is not covered.

With the exception of some parts of Article 725, the only main concern the NEC has with LV and communications wiring (Art 800 on) is the spread of fire and generation of toxic gasses and smoke caused by the material it's constructed with. This is unlike Chapter 3 wiring methods where current handling capacity, temperature, insulation resistance, installation etc are all factors. That's because Chapter 3 wiring handles voltage and current that has the potential to cause serious injury, property damage or death. Communications wiring handles little if any voltage and current.

My point about SO cord is that Chapter 3 wiring methods are inherently suitable for where it is installed. Type MC or NM (Romex) cables for instance have no riser or plenum versions. All can be run vertically but you can't use romex in a plenum space. Type SO, like all flexible cordage cannot be used for building wiring- within walls, floors ceilings. One of the reasons for that prohibition is that it does not meet smoke emission standards and pass the vertical flame test. Yet there is no prohibition against using it dropped vertically from a ceiling receptacle like our patch cord.

-Hal