# NEC Field Calc - Wire & Drop — Offline checks on the job site

> Offline checks on the job site (iPhone/iPad app by 伟英 刘.)

- Source: https://appshunter.io/ios/app/nec-field-calc-wire-and-drop/id6814713397 (this page in markdown: same URL + `.md`)
- Developer: [伟英 刘](https://appshunter.io/developer/1820225818)
- Category: Utilities, Productivity
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English, Chinese (Simplified, China)
- Released: 2026-10-27
- Data updated: 2026-10-31

## What is NEC Field Calc?

「NEC Field Calc」· Offline NEC field calculators for voltage drop, wire size, and conduit fill—built for electricians who work where cell signal dies.

「Numbers you can show on the job—without a subscription.」

「NEC Field Calc」keeps the math on your phone: Ohm’s Law, voltage drop with Pass/Warn, reverse wire sizing, and Chapter 9-style conduit fill checks. Free tools stay free. Pro unlocks the field pack with a one-time lifetime purchase—no account, no ads, no cloud. Results are estimation aids; always verify against the NEC edition your AHJ adopts and manufacturer data before you install.

——— Key Features ———
1  Ohm’s Law
   · Enter any two of volts, amps, and ohms to solve the rest plus watts when you need a quick sanity check on a ladder or in a panel.
   · Large number fields and live results stay readable with gloves so you are not hunting tiny calculator keys mid-task.
   · Save a short history entry or share a one-line summary when an apprentice or inspector asks how you got the number.

2  Voltage Drop
   · Check percent drop and load-end voltage for the wire you already picked, then see Pass or Warn against your limit.
   · Free tier covers common single-phase copper runs with a clear 3% style target so everyday branch checks stay unlocked.
   · Pro adds three-phase, aluminum, power factor, and custom limits when commercial feeders need more than free defaults.

3  Wire Size
   · Reverse-size AWG from voltage, load, one-way length, and max drop so you stop oversizing copper “just to be safe.”
   · Considers ampacity temperature columns and current-carrying count when the pull has more than three current-carrying wires.
   · Result cards show why the size won—voltage drop versus ampacity—so you can explain the pick on a walkthrough.

4  Conduit Fill
   · Check fill percent for EMT and common raceways against Chapter 9 style limits, with Pass/Warn before you jam another THHN.
   · Flip to minimum-size mode: enter wire size and count to find the smallest trade size that still fits.
   · Pro also covers box fill volume, bend mark helpers for offsets and stub-ups, and grounding conductor lookup from OCPD rating.

——— Real-World Scenarios ———
· Long garage or outbuilding feeder: size the wire for voltage drop first, confirm ampacity, and keep the Pass card ready for inspection.
· Crowded EMT pull in a commercial corridor: run conduit fill or minimum trade size offline in a basement where signal dies.
· Apprenticeship study: practice Ohm’s Law and drop checks without paper tables, then share the result text with a mentor.

——— What Users Say ———
· 「Finally an NEC calc that works in the basement with zero bars—drop percent and Pass/Warn are what I show the inspector.」——@field_jman
· 「Lifetime Pro beat another subscription. Wire size plus conduit fill on one screen is what I use every rough-in.」——@copperpuller
· 「Big taps, dark UI, no account. My apprentice gets Ohm’s Law done without borrowing my handheld.」——@panel_foreman

——— Subscription ———
Unlock Pro features with a one-time lifetime purchase. There is no weekly, monthly, or yearly auto-renewing subscription for NEC Field Calc Pro.

Pro Lifetime — $1.99 (one-time)

Payment is charged to your Apple ID at confirmation. Lifetime Pro is a non-consumable unlock; it does not auto-renew. Manage purchases in Apple ID settings. If a trial or promo appears for another product, Apple’s sheet shows terms before you confirm.

Privacy Policy: https://aihejiudeyudaye.github.io/NECFieldCalc/privacy-policy.html
Terms of Use: https://aihejiudeyudaye.github.io/NECFieldCalc/terms-of-use.html
Contact: piaochensuifeng@gmail.com

「NEC Field Calc」——Field math for electricians who need NEC-grounded estimates offline, with Pass/Warn you can stand behind after you verify the code book.
【Download Now】Get the free tools today and unlock Wire Size, Conduit Fill, and advanced Voltage Drop forever when you are ready.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| NEC Field Calc Pro Lifetime | $1.99 | one-time |


## Is NEC Field Calc safe?

Not enough ratings yet to assess NEC Field Calc.

## Is NEC Field Calc legit?

NEC Field Calc - Wire & Drop appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for NEC Field Calc is 65 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 1 release)

### 1.0.0 — 2026-10-27

No release notes.

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All apps by 伟英 刘: https://appshunter.io/developer/1820225818

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*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 2026-10-31.*