A fence is the easiest light surface you will ever hang, and still the one I most often see done wrong. You are not fighting gravity off a gutter, and you are not climbing. But a fence has its own failure mode: sagging wire, cold-brittle plastic, and a cheap connector that ends up in a puddle.

The sag is physics and cold, not the fence

Strands droop within days because the wire sags under its own weight, and cheap clips every 1.5 metres let the whole run pool on the ground. In the cold it gets worse: the wire stiffens and sags harder. The fix is clips every 45 to 50 centimetres with a 6 to 8 mm jaw, and loops through the fence rather than nails.

I pulled a customer's strand off a cedar fence last December. The only broken spot was where a nail had pierced the insulation. The nail, not the bulb, caused the first fault, and the customer spent a week blaming the lights.

On a wide fence, loop the middle too. One loose span between two posts is the difference between a clean line and a pile of light on the grass. I have stood in the cold with long-nose pliers and re-looped an entire run in about twenty minutes. It is the cheapest fix in the whole business.

One more thing about loops: leave a finger of slack. A wire pulled tight across a fence in November is a wire that snaps in January when the temperature drops and the plastic contracts. The slack that looks sloppy to a customer is exactly what keeps the run alive through the cold snap.

The wire is the second failure

Cheap indoor mini sets carry PVC-coated wire that gets brittle at -10 C. PE-coated outdoor wire with an IP67 connector is the one that shrugs off a frosty week. The real killer, though, is UV. I have tested strands that survived a winter fine and then cracked in the following summer. The bulbs die first, the wire lasts, and after three or four seasons the coating crumbles. The 300 LED Christmas Tree String Lights I keep on hand for a fence is outdoor-graded for exactly that reason.

If you are doing a long fence line, a 500 LED Outdoor Christmas Chain Lights with a weatherproof plug is a different animal from a plug-in indoor set. And if the fence is far from a socket, a Solar Fence and Garden String Lights saves you the risk of running an extension cable through a gate or over a path where a mower or a dog will find it.

Spacing is a spec too. Bulbs every 10 centimetres read as a dense, finished line from the street; bulbs every 30 centimetres look like a gap from five metres back. Match the spacing to how far a viewer actually stands, because nobody judges your fence from the other side of the road.

The connector is the third one

IP44 means splash-proof, not pond-proof, and the connector is where nine out of ten fence runs fail, not the bulb. Keep the plug and any splice above the ground line, and check the outdoor rating stamp on the connector, not just the cable. The cheapest 4-pence connector always fails first, within the year.

On the electrical side, run two separate circuits from opposite corners of the fence instead of one long chain down the middle, and keep each outlet under 600 watts. The quality of the IP67 connector matters more than the number of bulbs on the strand.

Finally, label the plug. By mid-December you will have four or five strands on that fence and you will not remember which one is the tree, which is the fence, and which is the one your neighbour asked you to borrow. A scrap of tape and a pencil beat a memory that fails on the coldest night of the year.

Frequently asked

How long does Christmas string lights stay on a fence? With clips every 45-50 cm, outdoor-rated wire, and the plug kept dry, the run holds through the season and often past. The sag is solved by clip spacing, not wire length.
Should I nail Christmas string lights into the wood? No. A nail pierces the wire insulation and is the most common cause of the first fault. Loop the wire through the fence slats and secure it with clips instead.
How many LED strands can I safely connect to one outlet? Three to four 4-watt LED strands is the practical limit, and the outlet's 600-watt rating is the hard cap. Keep the run under that and use outdoor-rated connectors.