Ethernet cables generally maintain full speed up to 328 feet (100 metres), the industry-standard maximum distance for reliable signal transmission before issues like signal loss and interference become significant. This matters for anyone installing home or office networking, as choosing the wrong cable category for a given run length or target speed can lead to unexpected slowdowns or errors, particularly as households upgrade to faster-than-gigabit internet plans.

The rules vary by cable category: Cat5e and Cat6 both support 1 Gbps up to 328 feet, but Cat6 only sustains its full 10 Gbps rating up to around 180 feet, dropping off unpredictably beyond that rather than gradually. Cat6a, by contrast, supports 10 Gbps across the full 328 feet, making it the better choice for longer high-speed runs. For distances beyond 328 feet, the article recommends adding a network switch midpoint or switching to fibre optic cable rather than simply using an extra-long copper cable, and notes that Power over Ethernet (PoE) installations need particular care, as long runs may fail to deliver sufficient power even if data transmission holds up.