SparkRef is a free Progressive Web App. Voltage drop calculator, wire ampacity calculator, conduit fill, and the NEC articles you reach for daily — fast, offline-ready, NEC-cited. Built by a 20-year IBEW journeyman.
Built for IBEW journeymen · Apprentices · Foremen · Electrical contractors
Same NEC-compliant engine that ships in the app. Single- or three-phase, copper or aluminum, 14 AWG through 1000 kcmil. Change a value — watch the result move.
VD = (2 · K · I · L) / CM (single-phase) · VD = (1.732 · K · I · L) / CM (three-phase) · K = 12.9 (Cu) / 21.2 (Al) · NEC 210.19(A) Inf. Note 4: ≤ 3% branch · 215.2(A) Inf. Note 2: ≤ 5% combined.
Half a panel torn open. A conduit run estimated wrong. The foreman waiting. The code book is in your truck. Your phone is in your hand.
SparkRef is on your home screen. Voltage drop in eight seconds. Ampacity table one tap away. The answer cited by article. You finish the run, climb down, walk to the next one.
That's the moment SparkRef was built for. That moment is most mornings.
SparkRef is a free Progressive Web App that gives electricians instant, offline access to NEC code articles and field calculators. It runs in any modern browser, installs from sparkrefapp.com with no App Store, and includes voltage drop, wire ampacity, conduit fill, and box fill calculators with answers cited by NEC article. Built and maintained by Remy Bourgeau, a 20-year IBEW journeyman wireman from Washington State.
Real screenshots. Built for one-handed use on a ladder.
| Question | NEC code book | SparkRef |
|---|---|---|
| Find an article | Index → page → cross-reference | Search, three seconds |
| Voltage drop calc | By hand, on the back of a print | Live, NEC-flagged inline |
| Ampacity at 75°C | Table 310.16, manual derating | Auto-derated, ambient + raceway built in |
| On a ladder | Two hands | One thumb |
| Cost | ~$120 / cycle | Free · ~$19 one-time Pro (planned) |
| Updates | Buy the new edition | Updates with each cycle |
SparkRef Pro adds the complete offline NEC index, calculation history, saved favorites, and a few advanced calculators I'm still nailing down. Estimated $19 one-time. About a sixth of a new code book. No subscription, ever.
Yes. SparkRef v1.0 is free for everyone. A one-time Pro unlock (estimated $19) is planned for v1.1 with optional advanced features. No subscriptions.
Yes. SparkRef is a Progressive Web App. After first launch it caches everything you need locally and works in basements, mechanical rooms, and anywhere signal dies.
The current NEC cycle. When a new code year is published, SparkRef is updated and changes are flagged in-app.
No. SparkRef installs straight from your phone's browser. iPhone uses Share → Add to Home Screen. Android uses the menu → Install app.
Yes — iPhone (Safari), Android (Chrome), and any modern desktop browser. Same install method on each.
No. No tracking, no ads, no data sales. The optional waitlist email is used only to notify you once when Pro launches.
Full offline NEC index, calculation history, custom favorites, and additional advanced calculators. One-time unlock around $19. No subscription.
Costs you nothing.
Install SparkRef →