# Fault Current Calculator (PFC) vs JG Underfloor

The clearest difference is monetization model: JG Underfloor at free against Fault Current Calculator (PFC)'s paid. JG Underfloor also leads on ads (none vs shown) and iOS requirement (12.0 vs 15.0). Fault Current Calculator (PFC)'s advantage is review sentiment (33% vs 0%). On price, update cadence, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Both ship on a similar rhythm, roughly every 14 months. The most recent releases landed on October 14, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | Fault Current Calculator (PFC) | JG Underfloor |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[1.0 (2 ratings)](https://appshunter.io/ios/app/fault-current-calculator-pfc/id577611194/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | **33.3% of reviews** | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | Every 14 months | Every 14 months |
| Monetization | Paid | **Free** |
| Size | 10 MB | 177 MB |
| Requires iOS | 15.0 | **12.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Pro Certs Software Ltd](https://appshunter.io/developer/444429696) | [Reliance Worldwide Corporation aust. Pty. Ltd.](https://appshunter.io/developer/1638011999) |

## What reviewers say

### Fault Current Calculator (PFC)

[App page](https://appshunter.io/ios/app/fault-current-calculator-pfc/id577611194)

This app calculates prospective fault current (PFC) in kA and Amps for single and three-phase circuits. It allows users to input any two values (voltage, earth loop impedance, or PFC) to determine the third, aiding in selecting appropriate circuit breaker ratings.

**Highlights:** Calculate PFC from Zs/Ze and Voltage, Calculate Zs/Ze from Voltage and PFC, Calculate Voltage from PFC and Zs/Ze, PFC calculation in kA and Amps, Single and three-phase support, Input any two values to calculate the third

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

**In-app purchases:** none


### JG Underfloor

[App page](https://appshunter.io/ios/app/jg-underfloor/id1638011997)

Control your home's underfloor heating system with this intuitive app. Manage thermostats and timers for ultimate zone control and easy configuration of both RF and hard-wired systems.

**Highlights:** Connect to John Guest thermostats, Manage timers, Zone control, Configure RF systems, Configure hard-wired systems, Intuitive user interface

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Fault Current Calculator (PFC) free?

Fault Current Calculator (PFC) is free to download, with no in-app purchases.

### Is JG Underfloor free?

JG Underfloor is free to download, with no in-app purchases.

### Do Fault Current Calculator (PFC) or JG Underfloor have ads?

Fault Current Calculator (PFC) shows ads; JG Underfloor does not.

### Which is updated more often, Fault Current Calculator (PFC) or JG Underfloor?

Fault Current Calculator (PFC) ships an update every 14 months, and JG Underfloor every 14 months. Most recently, Fault Current Calculator (PFC) was updated on October 14, 2026 and JG Underfloor on October 10, 2026.

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