Lineman's Reference Downloads & RevenueLineman's Reference - XFMR LAB · App Store
Lineman's Reference - XFMR LAB is #10 in Education Paid in United States and charting in 1 of 30 countries we track.
Updated 8 Nov 2026 · rankings refresh through the day
DeveloperDigital Apprentice LLC
CategoryEducation
Price19.99 USD
Released
Rating★ 4.7 (429)
Version2.0.8
Age rating4+
First seen by us
24 Sep 2026
24 Sep 2026Installs (est.)10k+ worldwide
Lineman's Reference - XFMR LAB update history & changes
Last change · 10 events since 12 Sep 2021Full timeline ↓📦Updated to version 2.0.8📈New best rank in the overall chart: #101📈New best rank in the overall chart: #106📦Updated to version 2.0.7🆕First spotted by AppInsider🆕Released on the App Store
Full timeline · 10 events
- 📦Lineman's Reference - XFMR LAB updated to version 2.0.8Maintenance update.
- Delta Wye Closed: a long ground strap now clears when the coils are paralleled back.
- Live classes: a queue edit or catch-up from your instructor reaches your phone even if it was asleep. - 📈Lineman's Reference - XFMR LAB new best rank in the overall chart: #101Top Paid · All Apps · US
- 📈Lineman's Reference - XFMR LAB new best rank in the overall chart: #106Top Paid · All Apps · US
- 📦Lineman's Reference - XFMR LAB updated to version 2.0.7What's new in 2.0.7
- Sandbox: the Wye 5-Wire bank now builds a 50 kVA series pot behind the two 25s, the way it goes on the pole, and the ratings panel shows what that pot's two coils can carry. Overload a coil and the risk pill names it.
- Sandbox: a wye bank whose pots were left in series reads its true usable capacity.
- A privacy policy link in Settings.
- Small fixes across the labs and the lessons.… more - 📈Lineman's Reference - XFMR LAB entered the top 100Top Paid · Education · AU
- 📈Lineman's Reference - XFMR LAB charting in a new countryAustralia
- 📈Lineman's Reference - XFMR LAB new best rank in the overall chart: #114Top Paid · All Apps · US
- 🆕Lineman's Reference - XFMR LAB first spotted by AppInsider#6 in Top Paid · Education · United States
- 📦Lineman's Reference - XFMR LAB version 2.0.6No release notes
- 🆕Lineman's Reference - XFMR LAB released on the App Store
Collected from the stores by AppInsider since we first spotted the app. Dates are when we saw each change.
Rating
4.7 ★
429 ratings
Measured
Best rank now
#10
Education PaidMeasured
New ratings a week
13
▼ -23% vs the 2 weeks before
Measured
Lineman's Reference - XFMR LAB on the App Store
App details
App ID
1583878194
Publisher
Digital Apprentice LLC
On the store since
Sep 2021
5 years on the store
Minimum OS
iOS 16.0+
iPhone 8 and later
Devices
iPhone · iPad
Universal purchase
Content rating
4+
Languages
1
EN
Size
68 MB
Also listed in
Entertainment
Lineman's Reference - XFMR LAB downloads
Worldwide, per day, and installs to date. The band is open; the exact number is free with an account.
How this is calculated
Apple publishes no download counts. App Store downloads come from chart positions and daily rating growth per country, calibrated on Google Play install counts; lifetime installs from ratings worldwide × installs per rating. Confidence is the chance the real number is within half to double ours.
Where Lineman's Reference - XFMR LAB's downloads come from Modelled
Last 30 days: organic search, browsing the store, features and paid ads.
Active users
All platforms, worldwide. Free with an account.
Stickiness (DAU / MAU)
how many monthly users open it on a given day
Retention · share of new users still active
Day 1
Day 7
Day 30
Time spent · per daily user
Average time spent Pro
min a day
Sessions a day Pro
Time per session Pro
min
How this is calculated
Monthly users come from lifetime installs across every store, fitted on monthly active user figures companies publish; daily users = monthly × the typical daily/monthly ratio for the category. Confidence is the chance the real number is within half to double ours.
Where it ranks now
Every top chart it appears in across 30 countries.
| Country | Charts | Rank |
|---|---|---|
| United States | EducationPaid | #10 |
Apps near Lineman's Reference - XFMR LAB on the chart
Education Paid, around #10.
Ratings
App Store, worldwide.
Rating
4.7 ★
429 ratings
Measured
Ratings
429
Measured
Review momentum
ⓘ How we measure thisNew ratings a week
13
▼ -23% vs the 2 weeks before
Recent ratings
5.0★
vs 4.7★ lifetime
Review momentum
74/100
faster than 86% of Education apps
Review momentum (0-100) blends how fast the app collects ratings compared with other apps in its category (60%), whether that pace is speeding up (25%) and what recent raters give it (15%; recent stars well below lifetime pull it down). Ratings counts are read daily. A jump usually means a launch, a feature, ads or a new review prompt.
What users say about Lineman's Reference - XFMR LAB
From the 42 most recent App Store reviews in the US.
Users appreciate the app's concept for teaching transformer banking but are frustrated by frequent bugs and rigid validation logic that rejects correct connections. While helpful for apprentices, many feel the experience is hindered by technical errors and a lack of advanced customization options.
Mixed but leaning positive (62% of recent reviews give 4–5 stars). People like it for being useful, and its features and content. The main complaints are about crashes and bugs, and connection and sync problems. Recent reviews are more negative than earlier ones.
What people like
- Useful: “Great app an very very helpful for myself”
- Features & content: “Good learning/practice tool”
- Connection & sync: “This app seems to work pretty good to learn some standard transformer connections”
- Updates: “Any chance there is an update to add single bushing pots for the banks my co op uses them and this would be a great tool?”
Common complaints
- Crashes & bugs: “Good theory, too many bugs…”
- Connection & sync: “Shows wrong connection with right hook up”
About Lineman's Reference - XFMR LAB
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
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
Latest updates
2.0.8
Maintenance update.
- Delta Wye Closed: a long ground strap now clears when the coils are paralleled back.
- Live classes: a queue edit or catch-up from your instructor reaches your phone even if it was asleep.
2.0.7
What's new in 2.0.7
- Sandbox: the Wye 5-Wire bank now builds a 50 kVA series pot behind the two 25s, the way it goes on the pole, and the ratings panel shows what that pot's two coils can carry. Overload a coil and the risk pill names it.
- Sandbox: a wye bank whose pots were left in series reads its true usable capacity.
- A privacy policy link in Settings.
- Small fixes across the labs and the lessons.
2.0.6
