Issue
Cat5e / Cat6 Ethernet cable maximum distance
 
Product Line
Connexium
 
Environment
Ethernet networks
 
Cause
What is the maximum allowed length for a Cat 5e / Cat 6 cable?
 
Resolution
For Ethernet copper cabling when used for 10/100/1000BASE-T, the maximum allowed length of a Cat 5e / Cat 6 cable is 100 meters (328 ft). This consists of 90 meters (295 ft) of solid "horizontal" cabling between the patch panel and the wall jack, plus 10 meters (33 ft) of stranded patch cable between each jack and the attached device.

It must be 100m (328ft) or less in length to be certified. It is possible a longer cable will work, but it is not guaranteed. Shorter Cat 5 cables may also not work if there is a lot of Electromagnetic interference (EMI). Signal attenuation appears to be the limiting factor, too much signal loss and you can't guarantee 100 megabits per second.