This article explains why wired Ethernet cabling is limited to a maximum of 100 meters, covering the standards that define the limit, the underlying physical and timing constraints of twisted‑pair transmission, and practical considerations for different cable categories and PoE installations.
This article explains why wired Ethernet cabling—whether Cat 5, Cat 5e, or Cat 6—is limited to a maximum of 100 meters, covering the physical principles, CSMA/CD timing constraints, standards specifications, and practical installation considerations such as PoE and cable quality.
The article explains that the 100‑meter limit for Cat5e (超五类) Ethernet cables stems from voltage‑based binary signaling, copper resistance, characteristic impedance, and practical factors like signal attenuation, capacitance, and installation tolerances, recommending a design margin of no more than 90 meters for reliable performance.
