both designed to require a minimum of category 5 cable and also specify a maximum cable length of . Category 5 cable has since been deprecated and new installations use Category 5e. Shared cable 10BASE-T and 100BASE-TX require only two pairs (pins 1–2, 3–6) to operate. Since common Category 5 cable has four pairs, it is possible to use the spare pairs (pins 4–5, 7–8) in 10- and 100-Mbit/s configurations for other purposes. The spare pairs may be used for power over Ethernet (PoE), for two plain old telephone service (POTS) lines, or for a second 10BASE-T or 100BASE-TX connection. In practice, great care must be taken to separate these pairs as 10/100-Mbit/s Ethernet equipment electrically terminates the unused pins ("Bob Smith Termination"). Shared cable is not an option for Gigabit Ethernet as 1000BASE-T requires all four pairs to operate. Single-pair In addition to the more computer-oriented two and four-pair variants, the 10BASE-T1, 100BASE-T1 and 1000BASE-T1 single-pair Ethernet physical layers are intended for industrial and automotive applications or as optional data channels in other interconnect applications. The single pair operates at full duplex and has a maximum reach of (100BASE-T1, 1000BASE-T1 link segment type A) or up to (1000BASE-T1 link segment type B) with up to four in-line connectors. Both physical layers require a balanced twisted pair with an impedance of 100 Ω. The cable must be capable of transmitting 600 MHz for 1000BASE-T1 and 66 MHz for 100BASE-T1. 2.5 Gb/s, 5 Gb/s, and 10 Gb/s over a 15 m single pair is standardized in 802.3ch-2020. As of 2021, the P802.3cy Task Force is examining having 25, 50, 100 Gb/s speeds at lengths up to 11 m. Similar to PoE, Power over Data Lines (PoDL) can provide up to 50 W to a device. Connectors 8P8C modular connector: For stationary uses in controlled environments, from homes to datacenters, this is the dominant connector. Its fragile locking tab otherwise limits its suitability and durability. Bandwidths supporting up to Cat 8 cabling are defined for this connector format. M12X: This is the M12 connector designated for Ethernet, standardized as IEC 61076-2-109. It is a 12 mm metal screw that houses 4 shielded pairs of pins. Nominal bandwidth is 500 MHz (Cat 6A). The connector family is used in chemically and mechanically harsh environments such as factory automation and transportation. Its size is similar to the modular connector. ix Industrial: This connector is