# PP+ Joule Heating vs Lineman's Reference

The clearest difference is price: PP+ Joule Heating at $1.99 against Lineman's Reference's $19.99. Lineman's Reference's advantage is update cadence (every 4 weeks vs every 31 months) and chart position (#10 vs unranked). On ads, in-app purchases and device support there is nothing between them.

PP+ Joule Heating costs $1.99 and Lineman's Reference $19.99 up front. Neither carries in-app purchases, so what you see is what you pay.

PP+ Joule Heating ships an update every 31 months, Lineman's Reference every 4 weeks. The most recent releases landed on November 1, 2026 and November 7, 2026 respectively.

## The numbers

| Metric | PP+ Joule Heating | Lineman's Reference |
| --- | --- | --- |
| Price | **$1.99** | $19.99 |
| Rating | — | **[4.7 (432 ratings)](https://appshunter.io/ios/app/linemans-reference-xfmr-lab/id1583878194/reviews)** |
| Number of ratings | — | **432** |
| Positive reviews | — | 62.2% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 31 months | **Every 4 weeks** |
| Monetization | — | Paid |
| Best chart rank | — | **#10** |
| Size | 125 MB | 65 MB |
| Requires iOS | 18.0 | **16.0** |
| Devices | iPad | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [Polyhedron Learning Media, Inc.](https://appshunter.io/developer/458882328) | [Digital Apprentice LLC](https://appshunter.io/developer/1565687382) |

## What reviewers say

### PP+ Joule Heating

[App page](https://appshunter.io/ios/app/pp-plus-joule-heating/id804719524)

**Features:** macOS Compatibility

**In-app purchases:** none


### Lineman's Reference

[App page](https://appshunter.io/ios/app/linemans-reference-xfmr-lab/id1583878194)

**Currently charting:** #10 Top Paid · Education, #145 Top Paid (US App Store)

This app simulates electrical transformer banks, allowing users to practice wiring, metering, fusing, and faulting. It offers guided lessons for beginners and a sandbox mode for advanced customization and scenario-based challenges.

**Highlights:** Transformer bank simulation, Guided training lessons, Customizable sandbox mode, Scenario-based challenges, Interactive wiring and faulting, Progress tracking and quizzes, Reference diagrams and tools

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 👍 Great for learning
- 👍 Helpful for apprentices
- 👍 Useful practice tool
- 👍 Good concept
- 👍 Excellent labs and sandbox

**What reviewers complain about**

- 🐛 Too many bugs
- 🐛 App is clunky
- 🐛 Wiring issues
- 🐛 Incorrect diagrams
- 🐛 Incorrect quiz answers

**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

**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


## Frequently asked questions

### Is PP+ Joule Heating free?

PP+ Joule Heating costs $1.99, with no in-app purchases.

### Is Lineman's Reference free?

Lineman's Reference costs $19.99, with no in-app purchases.

### Do PP+ Joule Heating or Lineman's Reference have ads?

Neither PP+ Joule Heating nor Lineman's Reference shows ads.

### Which is updated more often, PP+ Joule Heating or Lineman's Reference?

PP+ Joule Heating ships an update every 31 months, and Lineman's Reference every 4 weeks. Most recently, PP+ Joule Heating was updated on November 1, 2026 and Lineman's Reference on November 7, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*