Wiring – Is it safe to have a POE switch in an attic

Since you are in a one-family dwelling, there is really only one important article to be aware of.

800.26 Spread of Fire or Products of Combustion. Installations of communications cables and communications raceways in hollow spaces, vertical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased. Openings around penetrations of communications cables and communications raceways through fire-resistant-rated walls, partitions, floors, or ceilings shall be firestopped using approved methods to maintain the fire resistance rating.

FPN: Directories of electrical construction materials published by qualified testing laboratories contain many listing installation restrictions necessary to maintain the fireresistive rating of assemblies where penetrations or openings are made. Building codes also contain restrictions on membrane penetrations on opposite sides of a fire resistance–rated wall assembly. An example is the 600 mm (24 in.) minimum horizontal separation that usually applies between boxes installed on opposite sides of the wall. Assistance in complying with 800.26 can be found in building codes, fire resistance directories, and product listings.

In a one- or two-family dwelling, you can use general type cable (CM, CMG, CMX) anywhere other than where plenum cable is required.

800.154(B)(3) One- and Two-Family Dwellings. Type CM and CMX cable shall be permitted in one- and two-family dwellings.

Or, under carpets.

800.154(C)(6) Under Carpets. Type CMUC undercarpet communications wires and cables shall be permitted to be installed under carpet.

I own a cape with two finished bedrooms upstairs. We have knee-walls like you, as well as a cap space above the rooms (your upper attic).

We had both the crawl spaces (lower attic) and cap insulated. At the time, we were told there are two types of attic insulation: hot roof and cold roof. In a hot roof, the insulation is attached against the roof between the rafters and the air in the attic is considered warm. On a cold roof, the floor of the attic is insulated, making a warm ceiling, and ventilation and circulation occur in the attic itself (air comes in through the soffit and rises to a ridge vent or other ventilation device).

Ventilation is important for your attic and roof, so you'll want to be careful what you block up.

In my house, we used blow in insulation on the floor of the cap, and we used batting and foam board in the crawl space. You'll want to setup a ripping station outside, and you'll cut the foam board into lengths that fir through your crawlspace door. You carry them in in pieces, nail them to the rafters with special nails, and then use insulating/foil tape to seal the seams.