Quick answer: Use exterior speaker cable with a UV-stabilised jacket, moisture-resistant insulation and a burial rating if it goes underground. Keep gauge at 14 or 12 AWG for long runs, seal every connector, and leave a drip loop before the cable enters a building.
Exterior Speaker Cable: UV, Burial and Temperature
Exterior speaker cable fails for reasons that have nothing to do with sound. Sunlight breaks down ordinary PVC, water enters a cut jacket and corrodes the copper, and freeze-thaw cycles crack a stiff insulation. The electrical specification still matters, but the jacket and the connectors decide whether the cable survives three summers. A cable rated for indoor use can work for a season and then turn brittle, which is why outdoor runs need a different product rather than a longer warranty.
Jacket and UV Resistance
Sunlight contains ultraviolet radiation that attacks the polymer chains in ordinary PVC, making the jacket brittle and chalky. An exterior cable uses a UV-stabilised PVC, polyethylene or a rubber compound that resists this breakdown. Black jackets are common because carbon black absorbs UV, but colour alone is not a rating. Look for a product description that states outdoor or UV-resistant, and prefer a cable with a thick jacket rather than a thin zip cord.
PVC, PE and Rubber
Polyethylene has good moisture resistance and is common for burial. UV-stabilised PVC is flexible and adequate for exposed runs. Rubber jackets resist cold and abrasion but cost more. The datasheet should state the intended environment.
Colour and Heat
A black jacket absorbs heat, which can soften PVC in direct sun. A light-coloured jacket stays cooler but shows dirt. In hot climates, route the cable in shade or conduit rather than across a sun-exposed roof.
Burial and Moisture
Direct burial requires a cable rated for underground use, usually with a polyethylene jacket and a moisture barrier. Ordinary speaker cable will absorb water through nicks and at the ends, and the copper will corrode. Run burial cable in conduit where possible, and seal the ends with heat shrink or a gland. If the cable enters a building below grade, leave a drip loop so water runs off before it reaches the entry point.
Direct Burial Ratings
A cable marked for direct burial has a jacket tested for soil contact and moisture. If the marking is absent, use conduit. Do not bury zip cord, even in conduit, unless the jacket is rated for the location.
Drip Loops and Sealing
A drip loop is a low point in the cable before it enters a wall or a box, so water drips off instead of running into the building. Seal connectors with self-amalgamating tape or a gel-filled connector.
Temperature and Movement
Outdoor cable expands and contracts with temperature, and PVC becomes stiff in cold weather. A cable installed tight in summer can pull on its connectors in winter. Leave a service loop at each end and avoid stapling the cable so tightly that it cannot move. In freezing conditions, do not flex a cold PVC cable sharply, because the insulation can crack. Rubber and PE jackets tolerate cold better than standard PVC.
Cold Weather
Below freezing, PVC stiffens and becomes brittle. Install with a larger bend radius and avoid sharp turns at the connector. If the cable must be moved in winter, warm it first or wait for milder weather.
Expansion and Support
Support the cable at regular intervals and leave a small slack at each end. A tight run across a wall can pull the connector out of the speaker when the cable contracts. Use clips that do not crush the jacket.
Gauge and Connector Protection
Long outdoor runs need heavier gauge because the distance is often greater than an indoor run. A 30 m run at 8 ohm should use 14 or 12 AWG to keep resistance under 5 percent. Use connectors rated for outdoor use, or seal standard connectors with adhesive heat shrink and tape. Keep connections above ground where possible, and inspect them annually for corrosion and water ingress.
Gauge for Distance
A patio run of 20 to 30 m at 8 ohm is comfortable with 14 AWG. For 4 ohm outdoor speakers, use 12 AWG or shorten the run. The cost difference is small compared with trenching.
Sealing Connections
Water enters at the connector, not through the jacket. Use gel-filled connectors, adhesive heat shrink or a sealed junction box. Re-inspect after the first winter, because freeze-thaw opens small gaps.
Exterior speaker cable ratings
| Rating | UV | Burial | Cold | Best use |
|---|---|---|---|---|
| Indoor CL3 | No | No | Moderate | Inside walls only |
| Outdoor PVC | Yes | No | Moderate | Exposed walls |
| Direct burial PE | Yes | Yes | Good | Underground runs |
| Rubber jacket | Yes | Some | Excellent | Cold climates |
| Plenum CMP | No | No | Moderate | Air-handling spaces |
Real-World Application Scenarios
A patio install uses 14 AWG outdoor-rated cable in conduit, with a drip loop before it enters the house and gel-filled connectors at the speakers. A garden run of 35 m uses direct burial cable in conduit, because the trench is deep and the cable must survive soil moisture. A coastal balcony uses silver-plated copper cable and sealed connectors to resist salt air corrosion. A pool area uses a rubber-jacketed cable in conduit and keeps the connectors above the splash line, because chlorine and sun are both hard on PVC. A garden office uses direct burial cable for the last 10 m and transitions to indoor CL3 at the building entry.
Related Guides on This Site
For in-wall ratings and boxes, read the in-wall speaker outlet box guide and the speaker wire wall plate guide. Gauge selection is covered in the speaker cable types guide.
Frequently Asked Questions (FAQ)
Q: Can I use indoor speaker cable outside?
A: For a short exposed run it may work for a season, but ordinary PVC becomes brittle in sunlight and cracks in cold. Use a UV-stabilised outdoor jacket for any permanent exterior run.
Q: Does exterior speaker cable need to be buried in conduit?
A: Direct burial cable can go in soil, but conduit protects it from digging, rocks and rodents. If the cable is not rated for burial, conduit is required. Either way, seal the ends.
Q: What gauge for an outdoor speaker run?
A: 14 AWG suits most 20 to 30 m runs at 8 ohm. Use 12 AWG for longer runs or 4 ohm speakers. The extra copper is cheap compared with reopening a trench.
Q: How do I stop water getting into the connectors?
A: Use gel-filled connectors or adhesive heat shrink, keep the connection above ground, and form a drip loop before the cable enters a building. Inspect after winter.
Q: Why did my outdoor cable turn brittle?
A: UV exposure broke down the PVC jacket. The cable was not UV stabilised. Replace it with an outdoor-rated cable and route it in shade or conduit where possible.