Quick answer: Indoor PVC cable is not made for weather. Outdoors it needs a UV-stable jacket, protection from standing water, and mechanical support that does not crush the pairs. Use gel-filled direct burial cable underground, UV-rated cable in conduit or on a catenary above ground, and fit surge protection at both ends of any run that leaves a building. Keep the 100 m channel limit including the outdoor section.
The failures are predictable: the jacket chalks and cracks in sunlight, water enters a nick and travels by capillary action, and a lightning strike nearby induces a surge on the copper. Each has a specific remedy, and none of them is a better grade of indoor cable.
What the environment does
Sunlight and temperature
Ultraviolet light breaks the polymer chains in a standard PVC jacket, which turns it brittle within a season. A UV-stabilised jacket, usually black polyethylene, resists this. Thermal cycling also works the cable: expansion and contraction at a connector can loosen the termination, which is why outdoor runs should have a service loop.
Water
Water in a cable raises capacitance and eventually corrodes the copper. Gel-filled cable blocks longitudinal water travel, and a flooded design is the only reliable option for direct burial. Conduit helps but does not guarantee dryness, because condensation forms inside it.
Choosing the right construction
| Route | Cable | Protection |
|---|
| Direct burial | Gel-filled, UV jacket | Sand bedding, warning tape |
| In conduit | Standard or gel-filled | Drainage, pull cord |
| On a catenary | UV-rated, messenger wire | Support every 50 cm |
| Between buildings | Fiber preferred | Surge isolation |
Surge and grounding
Copper running between buildings carries a difference in earth potential and picks up induced surges. Fit surge protectors rated for Ethernet at both ends, bonded to the local earth, and prefer fiber for the crossing if the distance or the exposure is significant. A surge protector that is not earthed does nothing.
PoE complicates this: a protector must pass the voltage and current without dropping too much, so choose one rated for the power level rather than a telephone protector.
Installation details that decide life span
Keep the bend radius at four times the cable diameter, support it so its own weight does not hang on a connector, and leave a drip loop where the cable enters a building so water runs off before it reaches the hole. Seal the penetration, and use an outdoor-rated enclosure for any connector that remains accessible.
For the indoor tail, transition to a normal patch lead at a Ethernet wall plate rather than running the outdoor cable to a device. Where the run exceeds 100 m, the fiber to RJ45 converter route removes the distance limit, and the Cat6a cable option gives margin for 10G indoors.
Practical scenarios
- Shed or garden office, 40 m: gel-filled cable in conduit, surge protectors at both ends, drip loop at each entry.
- CCTV camera on a pole: UV-rated cable with a service loop, and a PoE surge protector rated for the camera’s power.
- Two buildings on one site: fiber between them, copper only within each building.
- Temporary event run: use a ruggedised catenary cable and test it before the event, because a crushed jacket fails in the rain.
FAQ
Can I bury ordinary indoor cable?
It will work for a while and then fail. The jacket is not rated for soil contact or UV, and water will enter any nick. Direct burial needs a gel-filled, flooded construction; conduit reduces the risk but does not eliminate water.
Does outdoor cable need to be shielded?
Not necessarily. Shielded cable helps with induced noise and with lightning, but the shield must be bonded correctly at both ends. For long outdoor runs, fiber removes the problem rather than managing it.
How far can an outdoor run go?
The same 100 m channel limit applies, and the outdoor section counts towards it. If you need more, put a switch or a media converter in a weatherproof enclosure partway along, or use fiber.
