While it may be tempting to avoid using so many posts and simply run your cable railings as long as you wish, there are safety limits and building code mandates to abide by. Such regulations are in place to ensure your cable railing system maintains the proper tension and is safe for anyone in its vicinity.
Maximum Cable Run Guidelines
Multiple factors will influence how far you can run cable railing. On average, you can expect anywhere between 4 feet to upwards of 75 feet (for straight runs), so long as you’re using intermediate posts and/or spacer bars.
Of course, the length of your runs will depend on the following:
The above factors — along with the specs of your particular project and the cable railing system you’re using — will also influence how far you can run your cable lines. For residential cable railing that runs horizontally, we recommend a maximum cable run of 20 feet from one post to another to ensure proper tensioning.
3 Factors Influencing Your Maximum Cable Run
1. Post Spacing
Without secondary support from intermediate posts or spacer bars, you should distance your posts approximately four feet apart. You can always space your posts beyond four feet, but you’ll likely need extra support for your toprail and to prevent cable deflection.
2. Cable Thickness
Did you know that the material and thickness of your cables directly impact how your cable runs stretch and whether they will lose tension over time? Choose high-quality, stainless steel cable with low stretch capability yet great flexibility to accommodate your customized project.
3. Tensioning
As a general rule, the further apart you space your posts (without intermediate posts or other stabilizers), the less tension you’ll experience. The problem is that your cable railing becomes unsafe without proper tensioning, as it likely won’t pass the 4-inch Sphere Rule required under the International Residential Code (IRC). If your cable railing is unsafe, you won’t be able to use it, and you’ll be required to bring it up to Code.