# Voltbox: Electrician Toolbox > Wire, breaker & conduit calculators plus a full multimeter guide. Offline. Canonical page: [https://chrome-stats.com/d/com.tapforgestudios.voltbox](https://chrome-stats.com/d/com.tapforgestudios.voltbox) ## Overview - **ID:** `com.tapforgestudios.voltbox` - **Platform:** Android - **Type:** Android app - **Status:** Available - **Publisher:** TapForge Studios - **Category:** PRODUCTIVITY - **Downloads:** 7 - **Version:** 2.3.6 - **Last updated:** 2026-08-19 - **First published:** 2026-07-12 - **Publisher country:** US - **Size:** 6.76 MB - **Data as of:** 2026-09-08 - **Store listing:** [Google Play Store](https://play.google.com/store/apps/details?id=com.tapforgestudios.voltbox) - **Website:** [http://tapforgeapps.com](http://tapforgeapps.com/) - **Privacy policy:** [https://tapforgeapps.com/uploads/voltbox-privacy-10e4708e.html](https://tapforgeapps.com/uploads/voltbox-privacy-10e4708e.html) ## Description Voltbox is the field toolbox for electricians, apprentices, and serious DIYers — a
fast, offline set of calculators and references built by someone who's actually run
pipe and pulled wire. No sign-in, no clutter, no ads on your calculations. Just the
numbers you need, on the job, in your pocket.

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WHAT'S INSIDE
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⚡ WIRE & BREAKER SIZING (new)
Enter a load in amps — or watts and voltage — and Voltbox returns the minimum
conductor, the standard breaker (NEC 240.6), the largest breaker that conductor may
legally carry, and the equipment ground from Table 250.122. A breaker-to-conductor
quick chart for 60 °C and 75 °C terminations and a common-circuits reference come
built in.

🔌 MULTIMETER GUIDE (new)
Learn to use your meter the right way, written around the Fluke meters most techs
actually carry — the 115, 116, 117 and 87V, plus the clamps. Safety and CAT ratings,
the live–dead–live check, input jacks, symbol legend, voltage, continuity and
resistance, ghost voltage and low-Z, and the mistakes that cost fuses. Advanced
sections cover current measurement, capacitance, diode, frequency, temperature,
microamp flame-rod testing, and a full field-procedure playbook.

📐 CONDUIT BENDING
90° stub, back-to-back, offset, three-bend saddle, four-bend saddle, and rolling
offset. Enter your numbers and get exactly where to mark and how far to bend — marks
shown as tape-measure fractions with the decimal underneath.

🧮 OHM'S LAW
Enter any two of volts, amps, ohms, or watts and Voltbox solves the other two, with
the formulas shown so you can check the work.

🧵 CONDUIT FILL
Add your conductors by type, size, and quantity, pick the conduit, and get the
smallest trade size that stays within NEC Chapter 9 fill percentages.

🎨 RESISTOR COLOR CODE
A 4, 5, or 6-band picker with a live-drawn resistor and computed value, tolerance,
and temperature coefficient.

📊 WIRE AMPACITY
NEC 310.16 copper and aluminum ampacities at 60/75/90 °C with the small-conductor
rules built in.

📉 VOLTAGE DROP
Single- and three-phase voltage drop in volts and percent, with a 3% pass/fail check.

📦 BOX FILL
NEC 314.16 box-fill volume from conductors, devices, clamps, and grounds.

🔋 POWER & MOTOR
kVA to volts to amps (single and three-phase), plus a horsepower–kilowatt converter.

🌎 GROUNDING
Equipment grounding conductor (250.122) and grounding electrode conductor (250.66)
sizing.

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WHY VOLTBOX
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• Works 100% offline — in the panel, the attic, the crawlspace, no signal needed.
• No account and no personal data collection. Your calculations never leave the phone.
• Clean, readable, one-handed layout that works with gloves on.
• Light and dark themes that follow your system setting.
• Built and maintained by a working-trade developer, not a content mill.

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FREE & PRO
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Most of Voltbox is free, including Ohm's law, resistor codes, conduit fill, ampacity,
grounding, the everyday conduit bends, the Wire & Breaker sizer at standard
conditions, and the core of the Multimeter Guide.

Voltbox Pro is a one-time purchase — no subscription. It unlocks the advanced conduit
bends, Voltage Drop, Box Fill, Power & Motor, the Wire & Breaker derating engine
(ambient temperature, raceway bundling, termination ratings), and the advanced half
of the Multimeter Guide — and it removes the single banner ad.

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Voltbox is an estimating and reference aid. Always verify against the edition of the
National Electrical Code (NFPA 70) adopted in your jurisdiction, and follow your
employer's safe-work practices and NFPA 70E. Work de-energized whenever possible.

NEC® and NFPA 70® are registered trademarks of the National Fire Protection
Association. Fluke® is a registered trademark of Fluke Corporation. TapForge Studios
is not affiliated with, sponsored by, or endorsed by the NFPA or Fluke.

Questions or a feature request? contact@tapforgeapps.com ## Rankings - #2,881,336 — Overall ## Permissions and access ### Permissions - `android.permission.ACCESS_ADSERVICES_AD_ID` - `android.permission.ACCESS_ADSERVICES_ATTRIBUTION` - `android.permission.ACCESS_ADSERVICES_TOPICS` - `android.permission.ACCESS_NETWORK_STATE` - `android.permission.FOREGROUND_SERVICE` - `android.permission.INTERNET` - `android.permission.WAKE_LOCK` - `com.android.vending.BILLING` - `com.android.vending.CHECK_LICENSE` - `com.google.android.gms.permission.AD_ID` - `com.tapforgestudios.voltbox.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION` ## Similar extensions and apps - [VOLTS: Electrical Reference](https://chrome-stats.com/d/com.corzohub.volts) — 35 users - [Voltix Electrical Calculators](https://chrome-stats.com/d/com.christhrower.voltix) — 23 users - [VoltWise - Electrician Toolkit](https://chrome-stats.com/d/com.developermcd.voltwise) — 8 users - [Electrician Calculator Pro 26](https://chrome-stats.com/d/com.flysky.electriciancalc) — 15 users - [VoltTool Electrical Calc](https://chrome-stats.com/d/com.dhgdevtools.volttool) — 147 users - [ProVolt: Electrical Calculator](https://chrome-stats.com/d/com.integratedapps.provolt) — 6 users - [VoltCraft Calc](https://chrome-stats.com/d/com.misbar.voltcraftcalc) - [Electrician ProCalc](https://chrome-stats.com/d/com.fieldcalc.electrician_procalc) — 63 users - [Voltkit: NEC Conduit Fill Calc](https://chrome-stats.com/d/com.chora.Voltkit) — 15 users - [Fieldwatt Electrician NEC Calc](https://chrome-stats.com/d/com.fieldwatt.app) — 23 users - [Electrician Calculator +](https://chrome-stats.com/d/com.electriciancalculatorplus) — 7 users - [ElectriCalc: Electrician Calc](https://chrome-stats.com/d/com.electricalc.android) — 51 users --- Source: [Chrome-Stats](https://chrome-stats.com/d/com.tapforgestudios.voltbox)