Kopperfield vs NEC Electrical Load Calculator

Save time and money. Get ready for permits and projects with faster and easier design tools from Kopperfield, including load calcs, line diagrams, panel schedules, and more. Once logged into your Kopperfield account, you'll enjoy our: * Load calculator: Easy-to-use interface pre-loaded with common appliances and their standard output values from the National Electrical Code. Add information on the property and your calculation will automatically update. Supports both commercial and residential calculations, as well as the Standard (NEC Article 220 Part III), Optional (NEC Article 220 Part IV), and 2026 Standard (NEC Article 120 Part III) methods. * Single line diagram tool: Contains dozens of common templates and electrical symbols to make it easy to generate new diagrams and share them with your team. View diagrams from any device and create new templates on tablet or desktop for your whole team to use. * Panel schedules: Includes tools to complete panel schedules and create labels for electrical panels. Drag-and-drop interface makes it easy to arrange and customize circuits for both split-phase and three-phase projects. * NEC chatbot: Custom chatbot with advanced search capabilities to quickly reference specific sections of the 2017, 2020, or 2023 National Electrical Code. Includes the following features: * Fast PDF outputs: instantly generate a downloadable, one-page PDF report of your load calc, line diagram, or panel schedule to share with inspectors and customers * Smart property data: enter the property address and we’ll pull in the square footage for any customer project or electrical load calculation * AI panel photo processing: upload a photo of an electrical panel to automatically add items to your load calculation or panel schedule * Team dashboard: store your team's projects and documents in one place for easier management, access, and review *Single and three phase options: use a variety of nominal voltages for residential and commercial building types, including: 120/240V, 120/208V, 120/240V, 208Y/120V 3Ø, 240V 3Ø Delta, 240V 3Ø Hi-leg Delta, 347V 3Ø Delta, 480Y/277V 3Ø, 480V 3Ø Delta, 600Y/347Y 3Ø, 600V 3Ø Delta. * Standard scenarios: generate load calcs for scenarios including single family homes (standard and optional methods), multi dwelling units (i.e., duplex, triplex, quad), 120/208v (three-phase power) dwellings, accessory dwelling units and additions, commercial occupancy types, and heat pumps * Common appliance defaults: choose from a pre-loaded list of common appliances and standard output values that you can adjust for every load calculation * EV charger inputs: include EV charger values to any load calculation, essential for modern homes

NEC Load Calculator sizes services, feeders, motors, branch circuits, panels and cable tray using the 2023 NEC — and every result shows the article citation, the demand factor table used, and the step-by-step math. Export any calculation as a PDF for permit submission. Built for electricians, electrical contractors, engineers and inspectors who need an answer they can check against the code book — not just a final number. WHAT YOU CAN CALCULATE • Residential service size — dwelling unit load calculation, standard method (NEC 220.40–220.55) and optional method (220.82). General lighting, small appliance and laundry circuits, fixed appliances, dryer, ranges and cooking equipment, HVAC, with 230.79(C) service minimums. • Commercial feeder and service — NEC 220.12, 220.44, 220.60 and 430.24. Lighting, receptacles, motors, HVAC units, sign circuits and demand factors. • Branch circuit wire and breaker size — conductor and OCPD sizing per NEC 210.19, 310.12 and 310.15(B)(1)(a). Continuous loads, conduit fill derating and ambient temperature correction, 120V through 480V. • Motor circuits — conductor, overload and OCPD sizing per NEC 430.22, 430.32 and 430.52, with full motor table lookups by horsepower, voltage and phase. • Panel schedule — circuit-by-circuit panel editor with phase balance, loading percentage and imbalance per NEC 220.40 and 220.87. • Cable tray — tray fill and ampacity derating per NEC 392.22(A) and 392.80(A). Ventilated trough and solid-bottom trays, small-cable fill-area limits and the 90% width rule for large cables. PANEL LAYOUT FROM YOUR LOAD CALC Turn a load calculation into a panel layout: circuit numbers, breaker sizes, two-pole spans and spare spaces, arranged the way a real panelboard is wired. Then fine-tune labels, phase assignment or breaker sizes in the Panel Schedule editor. SHOW YOUR WORK Every result lists the NEC article, the demand table and each step of the math, so you can verify it, explain it to an inspector or teach it to an apprentice. PDF REPORTS Export any result as a PDF for permits, job files or client records. INTERNATIONAL VOLTAGES Supports 220/127V and 440/254V systems (including 127V, 220V, 254V and 440V circuits) alongside standard US voltages, with a reminder to verify against NOM-001-SEDE in Mexico. IPHONE, IPHONE DUO AND IPAD Full-width layouts on iPad and the unfolded iPhone Duo, in any orientation. FREE AND PRO Residential and Branch Circuit calculations are free. A one-time Pro purchase unlocks Commercial, Motor, Panel Schedule, Cable Tray and PDF export. No subscription.