NEC Code Studio & Tools vs FILL ◦ Conduit Fill Calculator

This app is a visual reference library for electricians, electrical engineers, inspectors, and students — covering the National Electrical Code from the utility service entrance all the way to branch circuits and special systems. Browse 165 hand-picked illustrations organized into 11 categories: Distribution Systems, Service Entrance, Panel Layouts & Schedules, Wiring Diagrams & Floor Plans, Grounding & Bonding, Overcurrent & Motor Circuits, Load Calculations, Low Voltage & Special Systems, Safety & Code Compliance, Fire Alarm Systems, and Building Automation. Search Illustrations Find any diagram instantly across all 11 categories. Search by title, topic, or NEC article — results appear as you type. Recently Viewed Your viewing history appears at the top of Browse so you can pick up right where you left off. No hunting through categories to find a diagram you were just studying. Share Any Illustration Send any wiring diagram, riser, floor plan, or code reference directly from the gallery to colleagues, students, or inspectors. Residential Load Calculator (NEC Article 220) Calculate service load the standard NEC method — general lighting, small appliance and laundry circuits, large appliances, HVAC, and optional loads all in one place. Results update live as you type, with automatic demand factor application, service size recommendation (100A–400A), and conductor sizing for the hot, neutral, and grounding electrode conductor. NEC Reference Requirements Plain-English summaries of key NEC requirements organized by chapter — from working space clearances and conductor terminations to GFCI protection, grounding, and equipment installation rules. Search by article number or topic to find what you need in the field, fast. Illustration viewer features: Swipe left and right to flip through illustrations within any category. Pinch to zoom in for fine detail and pan while zoomed. Double-tap to zoom in, double-tap again to reset. Bookmark any illustration as a favorite for quick access. Works on iPhone and iPad. Full Dark Mode support. A practical field and study companion for anyone working with the NEC.

$7.99 once. No subscription. Try your first conduit fill calculation free, then get unlimited calculations with FILL Pro. US price shown; local App Store prices may vary. FILL helps electricians and apprentices check conduit fill on the job. Enter the conduit and conductors, tap Calculate, and see the fill percentage, wire area and applicable fill limit. No account required. CHECK FILL OR FIND A CONDUIT Check whether your wires fit a selected conduit, or use reverse sizing to find suitable conduit sizes. Review the result against the applicable NEC tables and local requirements. NEC 2023 AND 2026 Choose the edition used for your job. Calculations use Chapter 9 fill data for the supported conduit and wire types. FILL checks conduit fill for the supported catalog. Other installation requirements must be checked separately. SUPPORTED CONDUITS EMT, RMC, IMC, FMC, LFMC, PVC Schedule 40 and PVC Schedule 80. SUPPORTED WIRES THHN/THWN-2, XHHW, RHH/RHW and THWN in the sizes available for each type, plus TFN/TFFN fixture wire in 16 and 18 AWG. The picker shows the supported sizes. SHORT CONDUIT RUNS For qualifying nipples 24 inches or less, select nipple mode to use the 60% fill allowance. KEEP YOUR JOB RECORDS Pro includes calculation history, area labels, and text export and sharing. Completed calculations save when you calculate. Reopen a saved calculation in its original mode and code edition. Export a history backup to a location you choose and restore it on another device. History is stored locally; there is no automatic cloud sync. ONE FREE RESULT Prepare and edit your inputs before tapping Calculate. Your first completed result stays available. Further calculations require the one-time Pro purchase. FILL PRO - Unlimited calculations - Saved job history and area labels - Text export and sharing - History backup and restore - One payment, no subscription No ads. No account required. Light and dark appearance, clear result states and large controls for field use. Calculation math works on your device; purchasing and restoring access require a connection. NEC is a registered trademark of the National Fire Protection Association (NFPA). FILL is not affiliated with or endorsed by NFPA. Always verify results against the published code and local requirements.