Southwire Cablepull
January 1, 2026
End-to-end development of Southwire's Re3™ Cable Pull Calculator. An engineering-grade web tool used internally and by clients to determine safe cable routing through conduit systems without exceeding tension limits or sidewall bearing pressure.
Overview
Cable pulling sounds straightforward until you're dealing with a long conduit run, multiple bends, and a handful of cables with different jacket materials. The friction builds up fast, and if you exceed the sidewall bearing pressure limit or pull too hard, you've damaged insulation you can't see and won't know about until something fails later.
Southwire wanted a web app that could do this math accurately, handle real-world installation complexity, and work on a phone at a job site. Before Re3™, crews were either using Excel or handing work to competitor tools. Southwire needed something of their own.
My Role
I led the full build, from architecture to production. Worked closely with Southwire's engineering team to make sure the calculation logic matched NEC and NFPA 70 standards. Getting the math right mattered more than anything else on this one.
Technical Approach
State management was the hard part. Changing one input, say the conduit material or a bend angle, ripples through every downstream calculation immediately. Redux kept that manageable. The state tree maps directly to the calculation graph, so it's clear what depends on what and easy to trace when something looks off.
Metric and imperial support was trickier than expected. The fix was keeping all internal state in SI units and converting at the display layer only. That way rounding errors don't compound through five steps of calculation before you see a number.
TypeScript helped a lot with the friction coefficient tables, which vary by conduit material and cable jacket type. Modeling them as typed lookup structures meant bad combinations got caught at compile time rather than returning garbage at runtime.
Key Features
- Multi-cable pull configuration per conduit run
- Conduit fill percentage per NEC Chapter 9
- Sidewall bearing pressure monitoring (1,000 lbf/ft² limit)
- Jam probability for multi-conductor configurations
- 2D visualization of pull geometry with bend angles and segment lengths
- Metric/imperial toggle with SI-native calculation engine
- 15+ conduit types: EMT, PVC, HDPE, IMC, GRC, flex, cable tray