How to Hang 20 Ft Outdoor String Lights? | Measure, Anchor, Test

A 20 ft outdoor string light run gets hung by measuring the span, setting anchor points, testing the strand, then supporting the cord — a guide wire takes the load on longer spans.

For the full breakdown, see our best 20 ft String Lights guide.

Does a 20 ft run need a support wire? Not always, but it’s the part that outlasts the lights.

How Do You Plan Anchor Points Before Drilling Anything?

Measure between the two mounting surfaces first, then buy and drill. Measure the span, decide how much the strand should droop, and mark where the anchors go — a perfectly straight line looks stiff and adds tension. Plan for a gentle sag rather than a tight line. Working out hook placement before drilling saves a second round of holes.

Then set the hardware:

• Install hooks, screw eyes, or similar outdoor anchors at the marks.
• Pre-drill pilot holes, especially into deck framing, fascia, or brick.
• Keep the anchors rated for outdoor use and the weight of your strand.

If the anchors are spaced correctly, the strand should hang in a smooth shallow curve, not a taut line.

Should You Test the Strand Before Hanging It?

Yes — plug in and test the full strand before it goes up. Connect the sections and confirm every bulb works while you’re standing on the ground instead of on a ladder.

Start at the power source and work outward. This Old House’s installation walkthrough shows the same order: power source first, then the run. A dead bulb or bad section discovered on the ground saves a full rehang; discovered up high, it doesn’t.

Once the strand checks out, attach it to the anchors, clips, or a support wire. Attach loosely enough that the cord keeps its own slight movement — the tension comes later, if at all.

How Do You Hang a 20 Ft Span Without Stressing the Cord?

Thread the cord through the anchors or clips without pulling it tight. For spans over about 20 ft, add a steel support or guide wire with turnbuckles so the light cord isn’t carrying the whole load.

Home Depot’s guidance and Bob Vila’s how-to both call for reinforcing longer spans with a support wire rather than letting the light cord bear the weight.

For a run near a house, a strand clips to the support wire every few feet so the light cord only carries its own bulbs. Secure the strand every few feet with clips, zip ties, or hooks to cut drooping and the strain that lands on sockets and wire.

Don’t over-tighten. Pulling the strand hard strains bulbs, connectors, and the cord — snug and even beats tight.

Power is the other half of a safe hang. Use outdoor-rated extension cords and weather-resistant outdoor outlets or smart plugs, never an indoor-only cord run through a door gap.

What Separates a Clean Install From a Redo?

The difference is almost always tension and anchoring, not the lights. Here’s how the two common approaches compare on a 20 ft span.

Either way, the same rules apply: outdoor-rated components only, no tugging at the ends, and clips every few feet to keep the droop even. Weather-resistant outlets and cords round out the parts that aren’t about hanging at all.

In short: measure to the two anchor points, set the hardware, test the strand on the ground, then reinforce anything at or beyond 20 ft with a wire, clips, and a light hand on the tension. That gets the lights up once and keeps them up.