# Lineman's Reference - XFMR LAB — Transformer Training Simulator

> Interactive transformer lab simulator for learning and testing electrical connections. (iPhone/iPad app by Digital Apprentice LLC.)

- Source: https://appshunter.io/ios/app/linemans-reference-xfmr-lab/id1583878194 (this page in markdown: same URL + `.md`)
- Developer: [Digital Apprentice LLC](https://appshunter.io/developer/1565687382)
- Category: Education, Entertainment
- Price: $19.99
- Rating: 4.50/5 from 270 App Store ratings · 45 written reviews indexed
- Age rating: 4+
- Requires: iOS 16.0 · 65 MB
- Languages: American English
- Released: 2021-09-12
- Data updated: 2026-08-26
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/linemans-reference-xfmr-lab/id1583878194/reviews.md

## What is Lineman's Reference?

Learn it. Wire it. Energize it. Check your work.

Built by a working journeyman lineman for linemen and their apprentices. The XFMR Lab simulates distribution transformer banks driven by your own wiring — the metering, fusing, and faulting all behave the way you'd expect in the field.

NEW IN 2.0 — BUILT-IN TRANSFORMER TRAINING (Replacing XFMR INFO)

Six guided lessons take you from "what's a transformer?" to wiring a 3-pot bank:
• Start Here — What is a Transformer?
• Dual H Bushings — The Two Wirings & the Nameplate
• The Tap Changer — One Pot, Multiple System Voltages
• Three-Phase — The Three Phases and How They're Related
• Bank Identification — Delta or Wye, Open or Closed
• Your First Bank: Delta-Wye Closed (120/208)
• More lessons on the way!

Work the lessons in order, or jump straight to the labs.

ALSO NEW IN 2.0

• The Sandbox (Beta) — wire anything from scratch in a COMPLETELY-customizable lab, with live, vector-based voltage and fault logic baked in.
• Death Traps — scenario-based transformer traps linemen run into — and how to navigate them safely.
• A brand-new look across every lab — new graphics, sharper, faster, & easier to read in the field.
• Voltmeter you can now drag with two fingers; readings update as the leads move.
• Parallel the secondary coils by hand in wye secondary labs
• Stats that track lab completions, quiz scoring and for-fun stuff like the number of fuses you've blown.
• User Customizations - the user can now alter the spec of their labs; from grounding to parallel coil cutover-direction, requiring the 4th cutout, tap changer implementation and more.
• 2.0 is FREE for everyone who already owns XFMR Lab — thank you for years of feedback and encouragement.

WHAT YOU GET

Single Phase — Single Bushing · Dual Bushing
Three Phase (closed) — Delta-Delta · Delta-Wye · Wye-Delta · Wye-Wye
Three Phase (open) — Open Delta-Delta · Open Wye-Delta
Misc — Paralleling · 4th Cutout · Death Traps (6 Scenarios)
Advanced — Straight 480 · 240/480 · 277/480 · Corner-Grounded 240/480 · Wye-Wye 5-Wire (120/240 + 120/208) - all now able to be wired up Wye AND Delta on the topside
The Sandbox (Beta)
EVERY FUTURE UPDATE IS FREE - THE APP IS A ONE-TIME PURCHASE. I'm always working on new updates.

TOOLS & REFERENCE

• Volt, ohm and rotation meters with real behavior
• Nameplate, secondary coil and tap changer animations
• Reference diagrams for every standard bank

Learning Mode walks apprentices through every wrong-connection check. Journeymen and experienced users can keep this turned off if they'd like.

QUIZZES

• Classic Quiz — Select each lab you want in your quiz - with graded scoring across each lab.
• Advanced Quiz — You're provided with the job-site info and need to pick the right nameplate and coil setup, then wire it.
• Bank ID - A beginner's quiz tied into the new XFMR Training lesson plan. The user is provided with different primary and secondary wirings and must correctly identify them.

Used by 30,000+ linemen since 2021.

Questions? Suggestions? Reach me at info@digitalapprentice.net

## Key features

- Transformer connection simulation
- Volt, ohm, and rotation meters
- Abnormal voltage and fuse explosion simulation
- Transformer nameplate and coil inspection
- Quick reference diagrams
- Informational reading material
- Quiz and advanced quiz modes

## Chart rankings

- #7 in Top Paid · Education (US App Store)
- #126 in Top Paid (US App Store)

## What do users think of Lineman's Reference?

Overall sentiment: mixed

**Pros**

- 👍 Great for learning
- 👍 Helpful for apprentices
- 👍 Useful practice tool
- 👍 Good concept
- 👍 Excellent labs and sandbox
- 👍 Helps memorize bank building
- 👍 Great training reference
- 👍 Awesome app

**Cons**

- 🐛 Too many bugs
- 🐛 App is clunky
- 🐛 Wiring issues
- 🐛 Incorrect diagrams
- 🐛 Incorrect quiz answers
- 🐛 Voltmeter not working
- 🐛 Limited transformer options
- 🐛 Confusing connection requirements

**Commonly reported bugs**

- Tutorial loop
- Lines not connecting
- Cannot wire up all banks
- WYE Delta is wrong
- Cannot bus secondary x2 to x2 bushing for delta secondaries
- Cannot select subtractive transformers
- Wiring on X bushings not to exact phase
- H2 to neutral connection issues
- WYE Delta bank gives wrong voltage read
- Fuse blows when attaching case grounds in delta secondary
- Wrong wiring in diagram for 277/480 Wye/Wye bank
- HV on transformer name plate is wrong
- Shows wrong connection with right hook up
- Paralleling cans connection issue
- Voltmeter does not work
- Cannot drop leads to voltmeter on bottom two phases
- No option to select transformers
- No option for primary voltage
- No 277/480 option
- No additive/subtractive options
- Cannot pick secondary and primary side voltages
- App tells user bank is wrong when it's correct
- App incorrectly identifies bank type
- Cannot put voltmeter on C phase secondary leads in horizontal screen
- Cannot create 277/480 and straight 480 banks
- Cannot manually parallel secondary windings
- Lines too close to bottom of screen
- Cannot look back at bank during quiz
- High side H2 tied to ground in WYE delta
- Only allows 120/240 or 120/208 hookups
- Voltmeter not reading correctly when paralleling
- App says something is wrong but doesn't specify correction
- App keeps blowing doors on a correct connection

**Most requested features**

- Ability to build own banks
- Add tap changer settings
- Add vector charts
- Add more labs with different scenarios
- Create your own bank option
- Add a WYE bank that stays in series
- Add hints button
- Add power banks
- Add single bushing pots
- Add 480 banks
- Include transformers of different polarities
- Add 4th cutout to WYE delta banks
- Add additive and subtractive transformers
- Select transformers from a list
- Tie three phase secondary legs on open secondary lines
- Add lighter bank category
- Expand into metering
- Add open delta WYE bank
- Practice drawing vectors
- See vectors for transformers
- Ability to cut over pots
- Add 240/480/277 and 277/480 options
- More in-depth internals

## Recent user reviews (10 of 45)

All indexed reviews: https://appshunter.io/ios/app/linemans-reference-xfmr-lab/id1583878194/reviews.md

### 1/5 — Tutorial

*2026-07-23, version 2.0.3*

Will not let me out of the tutorial I have completed it multiple times I just want to practice on banks and the different kind paid $20 and I can’t do anything but a tutorial over and over again

### 5/5 — Great for storm

*2026-07-11*

Excellent labs and sandbox, has literally everything

**Developer response:** Thanks for the review!

### 2/5 — Great concept but to many bugs

*2026-05-14, version 1.3.02*

App is far to clunky, not worth using when you can only wire up 1/3 of the banks due to the lines not connecting.

### 5/5 — Very useful!!!

*2026-01-22*

I’m a co-op student and I play around with this app a lot! It’s definitely going to help a lot in the future!!

**Developer response:** Thanks for the review! I'm glad you find it helpful!

### 5/5 — Good app

*2025-12-03, version 1.3.02*

Learning a lot from this app. Only problem I’ve come across is how to tie the H1/H2 bushings to the tank ground and neutral

### 4/5 — WYE Delta is wrong

*2025-11-20, version 1.3.02*

Your eye delta is wrong. Other than that good app.

### 4/5 — Needs a bug fix

*2025-09-17*

Great app just noticed that on some of the banks you can’t bus the secondary x2 to x2 bushing for delta secondary’s.  It use to work but if the developers can fix that then it would get that 5th star in my book

**Developer response:** Why would you want to bus Delta secondaries across X2's? Delta secondary connections can only have one neutral reference. Unless I am misunderstanding you, which may be the case. Please reach out to me at info@digitalapprentice.net!

### 5/5 — Very helpful

*2025-04-11*

The app has some flaws but nothing you can’t work around. Helped me a lot on learning transformer configurations.

**Developer response:** Please reach out to me at info@digitalapprentice.net with any issues so I can get them corrected. Thanks!

### 3/5 — Good app, but not perfect

*2025-01-23*

I really like this app, I recommend it to my apprentices to learn the concept of banking transformers. What I do no like is that I can’t select to build banks with subtractive transformers. Not every system is less than 8kv. Also, when building a bank, if the wiring on the X bushings is not to the exact phase it’s drawn on the diagrams, it won’t accept the answer.

**Developer response:** Please reach out to me with screenshots of the secondary issues, this should not be the case. info@digitalapprentice.net

Also, a huge update is coming that will allow the users to change system voltage and therefore allow them to work with subtractive transformers.

Thanks!

### 5/5 — Great training reference!

*2024-08-29*

This is a great app, let me just start with that.
It would be great if you could build your own banks and check voltage and what not. The set diagrams are awesome but being able to play around with different connections would make it better. Also tap changer settings and info would also be a great addition.

## Frequently asked questions about Lineman's Reference

### What does the Lineman's Reference - XFMR LAB app do?

This app is a fully functional transformer lab simulator designed for linemen and apprentices. It allows users to study and learn various transformer connections, test their wiring with meters, and understand the consequences of improper connections. It also provides reference materials and quiz modes.

### What are the key features of this transformer simulator?

Key features include interactive simulation of single-phase and three-phase transformer banks, testing connections with volt, ohm, and rotation meters, simulating abnormal voltages and exploding fuses, inspecting transformer nameplates and secondary coils, quick reference diagrams, informational reading material, and quiz modes to test knowledge.

### Is this app free to use?

Yes, based on the provided information, the app is free to use and does not have in-app purchases or ads. The company also offers a 'Company Customized Experience' which may involve separate arrangements.

### What kind of transformer configurations can I learn and test?

The app includes labs for various configurations such as Single Bushing Topside, Dual Bushing Topside, Delta Delta Closed, Delta Wye Closed, Wye Delta Closed, Wye Wye Closed, Delta Delta Open, Wye Delta Open, Paralleling, 4th Cutout, Troubleshooting, Tutorial, Straight 480, 240/480, 277/480, Corner Grounded 240 or 480, and Wye Wye 5 Wire (120/240 & 120/208).

### How does the quiz mode work?

The quiz mode allows you to test your transformer wiring knowledge by completing a predetermined assortment of labs at random. Blowing fuses and attempting to check work will subtract from your overall score out of 100. There is also an 'Advanced Quiz' where you receive job-site information and must choose the correct transformer configuration.

## Version history (last 5 releases)

### 2.0.5 — 2026-08-09

Various Bug Fixes.

### 2.0.4 — 2026-07-28

New
• Amp clamp-on meter in the Sandbox: pull it out of the tool drawer, clamp it on any wire, and read the real current on that conductor. Try it on a loaded secondary leg (~100 A) vs. the primary jumper (~1.7 A), or on a 3-phase-loaded delta corner to catch the √3 between winding and line current.
• Fourth-cutout lab rebuilt as a guided, hands-on walkthrough. You energize the bank with the fourth cutout open and watch the ferroresonance blow happen, instead of just reading about it. Finishes with an unaided practice run you grade yourself.
• New customization option for starting Wye labs with the transformers already cut-over to the direction of your choice.

Improved
• If the app is waiting on Tutorial completion, tapping a locked button now tells you why and that it takes about 5 minutes. Longtime users upgrading from 1.x get a Skip Tutorial option after a quick look at what's new in 2.0.
• Learning Mode warning indicators now update live as you wire: the (!) flags appear and clear while you work, not only when you hit Check Work.
• The voltmeter steps out of the way while you drag a lead or draw a wire, then slides back so the reading stays visible.
• The correct-wiring diagram now shows the high leg on the phase you've actually set, instead of cycling through all three.
• Sandbox vector wheel now reads in the standard orientation (A at the 8 o'clock position) with a phase-displacement readout.
• Sharper splash screen update

Fixed
• Wire delete now works along the full length of every wire, including the ones that used to have dead spots, and no longer fires in the empty corner of an L-shaped run.
• Corner-ground and several banking labs no longer blow a fuse on some correct wirings.
• Voltages across the bank read true after a fuse blows, and a pot with its coils cut to series now reads the correct 240/120/120 split on wye labs.
• Banking nameplate always shows the correct primary voltage.
• Numerous other small bug fixes across each lab

(Existing users: thank you for the reports and feedback!)

### 2.0.3 — 2026-07-04

XFMR Lab 2.0 — the biggest update since launch.

NEW: Built-in Transformer Training (replaces XFMR Info). Six guided lessons take you from "what's a transformer?" to wiring a 3-pot bank — Start Here, Dual H Bushings, The Tap Changer, Three-Phase, Bank Identification, and Your First Bank: Delta-Wye Closed. More lessons on the way. More lessons on the way soon!

NEW: The Sandbox (Beta) — wire anything from scratch in a fully customizable lab, with live, vector-based voltage and fault logic baked in.

NEW: Death Traps — scenario-based transformer traps linemen run into, and how to navigate them safely (3 scenarios with more on the way).

NEW: User Customizations — set the spec of your own labs: grounding, parallel coil cutover direction, requiring the 4th cutout, tap changers, and more.

NEW: Bank ID quiz — a beginner quiz tied to the Training lessons; identify primary and secondary wirings on sight.

NEW: Stats — track lab completions, quiz scores, and for-fun numbers like how many fuses you've blown.

ALSO:
• A brand-new look across every lab — new graphics, sharper and easier to read in the field.
• Tap changer, nameplate, and secondary coil animations.
• Parallel the secondary coils by hand in wye-secondary labs.
• Advanced labs can now be wired Wye OR Delta on the topside.
• Voltmeter now drags with two fingers; readings update as the leads move.

2.0 is FREE for everyone who already owns XFMR Lab — and every future update is free, too. One-time purchase. Thank you for years of feedback and encouragement.

### 1.3.02 — 2025-02-10

Fixed a bug where rotation meter sometimes would not work properly.

### 1.3.01 — 2025-02-09

Fixed a minor bug in the Delta Delta Closed Bank lab.

## Apps similar to Lineman's Reference

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [EPA 608 Exam Prep & HVAC Test](https://appshunter.io/ios/app/epa-608-exam-prep-and-hvac-test/id6478236573) | 4.8 (1,618) | Free | Education |
| [Pocket Prep Skilled Trades '26](https://appshunter.io/ios/app/pocket-prep-skilled-trades-26/id1503583993) | 4.7 (699) | Free | Education |
| [Interplay Learning](https://appshunter.io/ios/app/interplay-learning/id1465704946) | 3.9 (48) | Free | Education |
| [IFSTA Instructor 9](https://appshunter.io/ios/app/ifsta-instructor-9/id1604765850) | 3.2 (17) | Free | Education |
| [EveryCircuit](https://appshunter.io/ios/app/everycircuit/id797157761) | 3.0 (65) | Free | Education |
| [ASE Test Prep Auto Exam 2026](https://appshunter.io/ios/app/ase-test-prep-auto-exam-2026/id6744390793) | 4.8 (2,044) | Free | Education |

## More apps by Digital Apprentice LLC

- [Lineman's Reference - URD](https://appshunter.io/ios/app/linemans-reference-urd/id6478995455)

All apps by Digital Apprentice LLC: https://appshunter.io/developer/1565687382

## Related topics

[xfmr lab](https://appshunter.io/ios/topics/xfmr-lab) · [transformer lab](https://appshunter.io/ios/topics/transformer-lab) · [xfmr](https://appshunter.io/ios/topics/xfmr) · [transformer lineman](https://appshunter.io/ios/topics/transformer-lineman) · [transformer labs](https://appshunter.io/ios/topics/transformer-labs) · [lineman's reference](https://appshunter.io/ios/topics/lineman-s-reference) · [transformers electrical](https://appshunter.io/ios/topics/transformers-electrical) · [lineman guide](https://appshunter.io/ios/topics/lineman-guide) · [top hand transformer lab](https://appshunter.io/ios/topics/top-hand-transformer-lab) · [llne man](https://appshunter.io/ios/topics/llne-man) · [lineman](https://appshunter.io/ios/topics/lineman) · [referencesontap](https://appshunter.io/ios/topics/referencesontap) · [welder education](https://appshunter.io/ios/topics/welder-education)

---

*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 2026-08-26.*