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I am considering running a low voltage cable (probably Cat6, but maybe fiber) up inside an exterior wall, between studs, from basement to 2nd floor in an existing home in the US. I should get riser- (or plenum-)rated cable due to the vertical aspect, right?

Would the cable need to be secured somehow inside the wall? If so, how? If not, can it just hang there for the vertical portion of the run?

Would I need to plug any horizontal things I drill through, e.g. the floor, say for fire stoppage? I'd want any modifications to be "up to code".

  • Exact code varies by where you are - at minimum, is this US, somewhere in Europe, Britain, etc.? – Joe Jul 3 '15 at 19:58
  • I'm in the USA. – cp.engr Jul 3 '15 at 21:15
  • Plenum rated cable is only necessary for a space, usually above a ceiling or below a floor, that can serve as a receiving chamber for air that has been heated or cooled to be distributed to inhabited areas. You should be fine with riser rated cable unless you're pulling it through an area that is designed as an air return. – mjohns Jul 3 '15 at 21:42
  • On my 2nd paragraph, if I'm reading NEC 300.19 right, in this case, a cable in a vertical raceway would only need to be supported near the top. I'm not sure if/how that applies if I have no raceway, though. – cp.engr Jul 4 '15 at 5:26
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Cable Rating

Plenum rated cable is only necessary for a space, usually above a ceiling or below a floor, that can serve as a receiving chamber for air that has been heated or cooled to be distributed to inhabited areas.

You should be fine with riser rated cable unless you're pulling it through an area that is designed as an air return or supply.

Securing Low Voltage Cable(s)

If you are pulling these cables in new construction, you would want to use low voltage staples to attach your cables every few feet to a stud or other framing member. Obviously in existing construction, unless you remove a bunch of drywall, this isn't feasible. It is acceptable to use the hole(s) in your studs, top plate, bottom plate, etc. to support the cable run. The NEC makes this exception even for electrical cable in remodel work:

NEC 334.30(B)

(B) Unsupported Cables. Nonmetallic-sheathed cable shall be permitted to be unsupported where the cable:

(1) Is fished between access points through concealed spaces in finished buildings or structures and supporting is impracticable.

Fire Block Penatrations

If you are drilling through a designated fire block (horizontal piece of framing in a stud wall), yes you are supposed to fill the hole with fire proofing caulk or spray foam. This might also apply to the top/bottom plates on the walls, but I do not know this for sure. Hopefully someone else here can shed some light on this. If you have enough access to caulk/foam the points where you drill holes, you could go ahead and do it for good measure.

In general, I'm not sure that much of NEC Article 300 even applies to low voltage installations. I recommend doing some reading related to NEC Article 725 or 800 where you will find the applicable references back to other articles, namely Article 300.

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