220-801 · Question #613
Which of the following cables is fire retardant?
The correct answer is D. Plenum. Plenum-rated cable uses a special low-smoke, flame-retardant jacket designed for installation in air-handling spaces where fire safety codes require it.
Question
Which of the following cables is fire retardant?
Options
- AUTP
- BPVC
- CSTP
- DPlenum
How the community answered
(45 responses)- A2% (1)
- B4% (2)
- D93% (42)
Why each option
Plenum-rated cable uses a special low-smoke, flame-retardant jacket designed for installation in air-handling spaces where fire safety codes require it.
UTP (Unshielded Twisted Pair) describes the shielding type of the cable pairs, not the jacket material, and standard UTP is not inherently fire retardant.
PVC jackets are common and inexpensive but release toxic chlorine gases and black smoke when burned, making them unsuitable for plenum spaces.
STP (Shielded Twisted Pair) describes the presence of foil or braid shielding around cable pairs to reduce EMI, which is unrelated to fire resistance.
Plenum cable is jacketed with materials such as fluorinated ethylene polymer (FEP) or low-smoke PVC that are rated to resist flame propagation and emit minimal toxic fumes when exposed to fire. It is required by fire codes (NEC Article 800) when cables run through plenum spaces - areas used for air circulation in HVAC systems - because a fire there can spread smoke and gases throughout a building.
Concept tested: Plenum cable fire-retardant rating and use case
Source: https://www.nfpa.org/codes-and-standards/nfpa-70-standard-for-electrical-installations/70
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