About WireSizes.com

Validation — how we verify each calculator

Before a calculator ships, it’s validated against three independent sources:

1. NEC code text directly — every coded value (ampacity, EGC size, demand factor, FLC) is cross-checked against the printed NEC 2023 article cited in the calculator’s help text.
2. Worked-example inversion — given a known good answer (e.g., from Mike Holt’s NEC instructor materials or a published utility design guide), we run the calculator backward and confirm it reproduces the reference output within rounding.
3. Cross-page consistency — values that appear on multiple pages (e.g., 12 AWG copper at 75°C = 25 A) are scripted-checked across rendered HTML so a typo or off-by-one drift on one page is caught automatically before deploy.

This last check is unique to our build — every page’s NEC table values flow from a single canonical module, so the cross-page consistency check is built-in. It caught two real factual errors during development: an off-by-one column shift in an early version of the wire-sizing-guide AWG table (claiming 14 AWG @ 60°C = 20 A when NEC says 15 A), and an aluminum 8 AWG @ 60°C value of 30 A where NEC says 35 A. Both fixes propagated automatically to every page that referenced them.

Correction policy — when we get something wrong

Despite cross-checks, errors occasionally make it to production. Our policy:

• Reporting: email support@wiresizes.com with the page URL, the field showing the wrong value, and the NEC article that contradicts it.
• Triage: safety-affecting errors (ampacity understated, EGC undersized) are fixed within 24 hours and announced via the page’s dateModified field.
• Non-safety editorial corrections (cost estimates, typical equipment ratings) are batched into the next monthly deploy.
• Backward compatibility: we never silently change a calculator’s output for the same inputs without noting the change in the page commit history (visible via git blame on the source file).
• Audit trail: the canonical NEC reference module is in git; every value has a discoverable commit date and rationale.

Roadmap — what’s coming next

Calculator and content additions on the near-term roadmap:

• NEC 2026 readiness: the next NEC edition publishes mid-2026; we will track the public input phase via NFPA’s document workflow and ship updated calculators within 90 days of publication.
• Per-amperage guides: dedicated “wire size for [30, 40, 50, 60, 90, 125, 150, 400] amp” pages mirroring the existing 100A and 200A guides. Each ~2,000 words with NEC-correct ampacity and EGC values.
• Reverse-lookup guides: “[14, 12, 10, 8, 6, 4, 2, 1/0, 2/0, 4/0] AWG ampacity” pages — what each conductor can actually carry at 60/75/90°C.
• Conductor-type pages: THHN vs Romex (NM-B), THWN vs THWN-2 vs RHW, USE-2 direct-burial, TC-ER tray cable — selection criteria and code restrictions.
• Color-code reference: the canonical wire color chart for ungrounded / grounded / EGC across NEC 200, 210, 250 — a top citation target for AI assistants.
• Specialty calculators: water heater sizing, induction cooktop, mini-split heat pump, generator transfer switch sizing.
• Performance: we are collecting Core Web Vitals data via Vercel Speed Insights and will optimize the slowest calculator pages once we have a stable LCP baseline (3+ months of real-user traffic).
• API access: a read-only JSON endpoint for NEC table values and calculator outputs, intended for educational and integration use.