Support & help
Need help, found a bug, or want a calculator added?
The fastest way to reach me is email. I read every message.
Please include your device model, iOS version, the app version (Settings → About), and the numbers you entered. For a calculation that looks wrong, the inputs matter most — that is usually enough to reproduce it straight away.
Electrical Pro Toolkit is a set of twelve calculators for electricians, solar installers and engineers.
| Tool | What it works out |
|---|---|
| Voltage Drop & Cable Sizing | Drop across a run for 1-phase, 3-phase and DC |
| Cable Ampacity & Derating | Capacity after ambient, grouping, insulation and install method |
| Motor Sizing | Full load amps and inverse-time breaker size |
| Short Circuit | Fault current at a transformer secondary |
| Conduit Fill | Maximum conductors for a conduit |
| Earth Conductor | Protective conductor by table and adiabatic equation |
| Power Factor Correction | Capacitor bank size to reach a target cos φ |
| Lighting | Fixture count by the lumen method |
| PV String Sizing | Modules per string inside the inverter DC window |
| Solar Yield | Monthly and yearly production via PVGIS |
| Battery Bank | Off-grid capacity from load and autonomy |
| Ohm's Law | V, I, R and P from any two |
Because the app checks two limits, not one. A cable must both stay within the voltage drop target and carry the current without overheating. Many calculators only check voltage drop.
The app sizes to whichever limit governs and says which one it was, in the breakdown under the result. If the thermal limit is driving it, look at your ambient temperature and the number of grouped circuits — derating there is often the reason.
You should not. Comma and point decimals are both accepted, so 2,5
and 2.5 mean the same thing in every language. If you see otherwise,
please email me the exact input — that is a bug worth fixing quickly.
DC has no standard nominal voltage. A 12 V battery bank and a 600 V PV string are both DC, and guessing between them would change the percentage by an order of magnitude. Enter the actual bus or string voltage and the percentage appears.
The drop in volts is always shown, since it does not depend on system voltage.
They are widely published reference values for common cable constructions, following the IEC 60364-5-52 derating method. They are a convenience, not a substitute for your cable's data sheet.
Always verify against the manufacturer's rating and the standard that applies in your jurisdiction before installing.
Both, in different places. Cable sizing, ampacity and earthing follow IEC 60364 practice. Conduit fill and breaker selection follow NEC tables. Each screen notes the basis it uses. Check that the convention matches your jurisdiction.
Yes, apart from one tool. Eleven of the twelve calculators run entirely on your device. Only the Solar Yield estimator needs a connection, because it queries the PVGIS service for irradiation data at your coordinates.
PVGIS does not cover the entire globe. If it rejects your location, the coordinates are likely outside its dataset. The other eleven calculators are unaffected.
Please ask. Requests from people doing the work are the best guide to what belongs in the app, and several tools exist because someone asked.
English, Spanish, French and German. Change it under Settings → Language. If a translation reads badly to a native speaker, I would genuinely like to know.
Results are estimates for planning. Verify them against the applicable standard, the manufacturer's data and local regulations before installing anything. The app states its assumptions on screen so you can judge whether they hold for your situation.