In the event of a fire in an office building, which of the following cable types should be installed to prevent toxic gas from burning PVC cable coatings?

CAT6a is a performance specification describing bandwidth and crosstalk characteristics; CAT6a cable is available in both standard PVC and plenum-rated jacket versions, so the category alone does not ensure fire safety.

Standard PVC cable jackets release toxic hydrogen chloride gas and dense smoke when burned, which can be deadly in enclosed spaces. Plenum-rated cable uses FEP (fluorinated ethylene polymer) or low-smoke PVC compounds that produce minimal toxic fumes and are self-extinguishing. Building codes such as NEC Article 800 mandate plenum-rated cabling in air-handling spaces where combustion products could circulate through a building's ventilation system.

A crossover cable is a twisted-pair cable with a specific pin-out wiring pattern used to connect similar devices directly; it is not a cable type defined by its jacket fire-resistance properties.

STP (Shielded Twisted Pair) refers to the addition of metallic shielding around cable pairs to reduce EMI, and is unrelated to the fire-resistance or toxicity of the cable's jacket material.