Resources
Free tools. No login. No upsell.
The same NEC-compliant calculators we built for our platform, available to everyone, no account required. Use them on the next job. No watermarks, no rate limits, no “upgrade for full results” nonsense.
Conduit Sizing Calculator
Determine proper conduit size based on NEC fill requirements.
Load Calculator
Residential and commercial service load calculations to NEC Article 220.
Voltage Drop Calculator
Wire sizing and voltage drop across distance, AC and DC.
Fault Current Calculator
Available fault current at the end of a conductor run.
Row Spacing Calculator
Solar panel inter-row spacing to avoid winter-solstice shading. Latitude, tilt, azimuth.
Guides
Reference articles for the rules behind the tools.
The NEC sections, design conventions, and inspection checks that drive what the calculators output. Bookmark for the next plan check or AHJ conversation.
NEC Compliance
NEC Service Disconnect Locations
NEC 230.70 / 230.71 / 230.85 / 705.11 walked through the way an inspector reads them — with the common rejection causes called out.
Solar Design
Solar Wiring Diagram Guide
What every PV (and PV + storage) wiring diagram needs: single-line vs three-line, conductor schedule, OCPD, EGC, AC disconnects, and the labels every AHJ checks.
Solar Design
Solar Panel Row Spacing
How inter-row spacing is computed at the worst-case sun angle of the year, with a live 3D viewer that rotates as you change azimuth and tilt.
Beyond the calculators
These tools are part of a bigger platform.
The same calculations run live as you design plansets in Solar Design Lab. AHJ rules check your design in real-time. Stamping from $150 per planset. Revisions included.