With their thin plastic casing, ordinary Ethernet cables will deteriorate quickly when exposed to the elements. For best results, outdoor Ethernet cables should be placed in a conduit and then buried under the ground about 15-20cm (6-8 inches) and at least that far away from power lines or other sources of electrical interference. PVC or other plastic pipe, installed with waterproofing, can work as a conduit. Ordinary CAT5 cable is not designed for outdoor uses, however - extreme temperatures and humidity will shorten the useful lifetime of such an outdoor network.
Special exterior or direct burial CAT5 cables should be used for outdoor runs instead of ordinary CAT5. Direct burial CAT5 costs more, but it is designed specifically for outdoor use. Exterior-grade Ethernet cables are waterproof and thus do not require conduit.
Both ordinary and direct burial CAT5 cables attract lighting strikes to some degree. Simply burying a cable underground does not lessen its affinity for lightning. CAT5 surge protectors should be installed as part of outdoor Ethernet networks to guard against lightning strikes.
A single Ethernet cable, whether indoor or outdoor, is only designed to function over a distance of about 100m (328 feet). Some networks operate successfully with Ethernet cables run 200m or more. When extended past the recommended limit of 100m, Ethernet reliability and performance may suffer, and results can vary from one cable to the next. Active hubs or other repeater devices can be installed with a series of CAT5 cables to greatly extend the range of an Ethernet outdoor network.