Standard Ethernet Cables Work Outdoors but Degrade Quickly, Report Warns

Outdoor temperatures and rain accelerate the problem, and the copper in an Ethernet cable lacks proper protection from lightning strikes and other elements, Engadget reports. For outdoor runs, the report recommends using a cable specifically rated for outdoor exposure, such as a direct-burial-rated cable for an in-ground run across a yard. Direct-burial cables are designed for long-term exposure to moisture and the physical pressure of soil, and the rating is printed clearly on the cable jacket. The report also advises installing surge protection on either end of any cable run.

There is a difference between direct-burial and outdoor Ethernet cables. Outdoor cables typically use a more weather-resistant polyethylene jacket, such as LLDPE or PE, instead of the standard PVC jacket, according to Engadget. These materials resist UV exposure, moisture, and wild temperature swings better. Direct-burial cables may use water-blocking tape, powder, or gel to keep the wire dry even if the outer jacket is damaged. Local ordinances may regulate buried wire, so the report says to check rules on conduit, depth, and permitted cable types.

For a short exterior run to an outdoor access point, a Cat6 outdoor-rated Ethernet cable is appropriate, the report says. Exterior cable runs should be secured with cable clips to avoid abrasion, and the cable should never be sharply bent. As an alternative to running copper outdoors, outdoor-rated fiber optic cables can avoid the risks, though any equipment exposed to the elements would still be at risk, Engadget notes.

To identify an outdoor-rated cable, users should check the printing on the cable itself, not the color or category label, according to the report. Terms like CMX, OSP, UV-resistant, sunlight-resistant, or simply outdoor are what to look for, along with jacket materials such as PE, HDPE, or LLDPE. The National Electrical Code requires communications cables installed in buildings to be listed and marked, and UL guidance notes that cable evaluated for outdoor use is marked outdoor or outdoor use, the report says. Documentation that comes with the cable will state whether it is approved for direct burial or wet locations.

The report also cautions that an outdoor-rated cable does not necessarily meet indoor fire safety requirements. An unlisted outdoor cable generally cannot run more than 50 feet inside before it needs to terminate and transition to an indoor-rated cable, and shorter is better, according to Engadget. Users unsure about local codes should check them, especially for permanent installations, the report advises.