# Voltbox: Electrician Toolkit — NEC Calculators & Wire Sizing

> NEC Calculators & Wire Sizing (iPhone/iPad app by GABRIELE CHESI.)

- Source: https://appshunter.io/ios/app/voltbox-electrician-toolkit/id6793043903 (this page in markdown: same URL + `.md`)
- Developer: [GABRIELE CHESI](https://appshunter.io/developer/6793043905)
- Category: Utilities
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 15.0 · 21 MB
- Languages: American English
- Released: 2026-07-30
- Data updated: 2026-08-13
- User reviews in markdown: https://appshunter.io/ios/app/voltbox-electrician-toolkit/id6793043903/reviews.md

## What is Voltbox?

Voltbox is a professional calculator toolkit for electricians, built around the NEC (National Electrical Code). Fast, accurate, and yours to own — pay once, keep it forever.

18 CALCULATORS

Fundamentals (free)
• Ohm's Law — voltage, current, resistance, power, series/parallel
• Wire & Cable Sizing — NEC ampacity lookup

Dwelling Load
• Load Calculation — dwelling feeder/service sizing (NEC 220)
• Range Demand — cooking appliance demand load (NEC 220.55)
• Generator Sizing
• Existing Load Evaluation — headroom check for adding new loads to an existing service

Circuit Design
• Voltage Drop — for any run length and load
• Motor / Transformer Sizing — full-load amps per NEC 430
• Grounding & Bonding — NEC 250.66 / 250.122
• EV Charging — NEC 625
• HVAC Circuit Sizing
• Feeder Tap Conductor — NEC 240.21(B)
• Spa Bonding Exemption
• Branch Circuit Sizing

Installation
• Conduit Fill — max conductors per conduit size, including bare wire
• Box Fill — junction box conductor capacity
• Conduit Bending — offset & 90° stub
• Light Meter — jobsite illumination check against OSHA/egress/IES minimums

WHY VOLTBOX
• One-time purchase for Pro — never a subscription, never a recurring fee
• Save and organize calculations by project
• Built for the job site: fast, no clutter, no login screens, works with no signal
• No account required — open the app and start calculating

Ohm's Law and Wire Sizing are free. Unlock Pro once to get every other calculator.

Voltbox is a reference tool based on the NEC. Always verify results against the current code edition adopted in your area and confirm compliance with a licensed electrician or your local inspector before performing any installation.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Pro Unlock | $8.99 | one-time |



## Version history (last 2 releases)

### 1.1.0 — 2026-08-10

9 new Pro calculators: Grounding & Bonding, Conduit Bending, EV Charging, HVAC Circuit, Generator Sizing, Existing Load Evaluation, Feeder Tap, Spa Bonding, and Branch Circuit Sizing.

New: Light Meter — check jobsite lighting against OSHA, egress, and IES minimums right from your phone.

Find tools faster with search and favorites on the home screen.

### 1.0 — 2026-07-30

No release notes.

---

*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-13.*