The method matters.
Ampxa applies engineering relationships to user-supplied project data. Each calculator displays its equation, units and scope beside the result. Arithmetic validation does not establish installation compliance.
Region settings
Every calculator uses US values and units for every visitor: 120 V, 240 V or the NEC motor-table voltages, 60 Hz, feet, AWG and kcmil. A Metric switch changes only how lengths, areas and volumes are shown. The region setting adapts invoices and estimates; outside the United States, calculator pages add a notice that the tools follow US NEC practice.
| Region | Invoice and estimate defaults |
|---|---|
| United States | USD · Sales tax · Letter paper |
| United Kingdom | GBP · VAT · A4 paper |
| Canada | CAD · GST / HST · Letter paper |
Detection and adoption
When explicitly enabled on a trusted host, country detection uses an edge-provided country header. Otherwise browser locale and recognized timezones suggest a region. An inconclusive result uses International, and a saved manual selection always takes priority.
NEC editions are adopted locally, and states and cities may amend them. The calculators follow US (NEC) practice only; other countries' wiring rules are not covered. Check the edition and amendments that apply to the project before designing.
What is validated
The project includes independent numerical cases for Ohm’s law, voltage drop, motors, transformer sizing, conduit geometry, fault energy, unit conversion and invoice totals. Every formula calculator is also checked for a finite default result, input bounds and unique routing. No licensed electrical review has been completed for this rebuild.
Code tables and complex tools
Copyrighted code tables are not reproduced. Users enter verified ampacities, correction factors, fill limits and disconnection data. Busbar sizing, motor connection schemes, surge risk and emergency-lighting design are clearly marked reference workflows instead of issuing unsupported ratings.
Engineering and invoice sources
- Schneider Electric — voltage drop relationships
- Schneider Electric — short-circuit impedance method
- GOV.UK — invoice information
- Canada Revenue Agency — invoice information for input tax credits
- NFPA — NEC adoption map
Source review: 14 October 2026. Invoice tax rates are user-entered; the app never infers tax registration or liability from a country.
See numerical validation cases →Corrections
Report the tool, all inputs and the expected answer with a source through Contact. A confirmed issue should receive a regression case before release.
36 calculators · 6 templates · 55 quick tools · 18 references. Calculators are the full, indexed calculator pages; quick tools are simpler, generated calculators.