Recommended Ethernet Cable Lengthsby David Lipscomb
Ethernet cables, like all copper wires, have a maximum transmission length. Although there is some leeway in using a cable run longer than recommended, inconsistent Internet or network performance may result. Regulating the lengths of each individual channel and link in the network is a way to help ensure the data arrives intact, and prevents a possible bandwidth bottleneck.
The total Ethernet run from the distribution or patch panel to the end component is the baseline environmental expectation in the design of Ethernet cables. In these cases, the maximum recommended link for a Category 5e Ethernet cable is 100 meters, roughly 330 feet. The cables used for this are assumed to be 22- or 24-gauge unshielded twisted pair Ethernet wires. Remember the 100-meter total includes jumper cables from wall plates to computers, and those have their own max length specifications.
Crosslinks are jumper cables, linking routers and switches. In this case, the recommended cable length is limited functionally to roughly 20 feet. This is rarely needed, since most of these devices are located in close proximity to one another. These distances are supported by the fact most of these devices have some degree of signal boosting and equalization. In all cases, using the shortest possible cable is recommended to retain flexibility in runs from these devices to the individual computers on the network.
Patch cords from the wall jack to the individual networked devices should remain under 3 meters, or 10 feet. Consider the location between the computer and wall jack when installing the cables and jacks, attempting to keep all within the 100-meter window. It is recommended you record and consult the initial Ethernet run from the patch panel to your local wall jack, adding this figure to the length of cable from the jack.
Ethernet cables should always be twisted fully up until the final inch of the end of the cable, as it enters the RJ-45 jack. Inconsistencies in this configuration will result in intermittent or failed network performance. Do-it-yourselfers need to remember these cables must be properly terminated using an RJ-45 connector with the appropriate modular crimping tool. All Ethernet cables must remain nick-free. Use of shielded twisted pair cables is recommended when the cables run next to AC power lines or other electronic devices, minimizing external interference.