Fault Current Calculator (PFC) vs JG Underfloor
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Fault Current Calculator (PFC)
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.
- 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
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Fault Current Calculator for iPhone and iPad is a fast, free tool for electricians, contractors, and engineers. Calculate Prospective Fault Current (PFC), Prospective Short-Circuit Current (PSCC), and Prospective Earth Fault Current (PEFC). Enter any two known values - voltage, loop impedance (Zs/Ze), or fault current - and the app instantly calculates the third. KEY FEATURES: PSCC and PEFC calculations: Calculate prospective short-circuit current for L-N or L-L faults and prospective earth fault current for L-E faults. Single-phase and three-phase support: Perform fault-current calculations for both system types. Automatic calculations: Enter any two known values to auto calculate the third. Loop-impedance calculator: Calculate Zs or Ze from voltage and prospective fault current. Formula display: See the formula used for each calculation so you can understand and verify the result. Works offline: Use the app in roof spaces, basements, plant rooms, and other locations without a signal. Dark mode and light mode: Maintain a clear display in different site conditions. 16 languages: Fully translated for electricians worldwide (af, ar, de, es, en, fr, hi, id, it, ja, ko, nl, pl, pt, ru, zh). Fast and free: A clean interface designed to deliver results without unnecessary steps. DEFINITIONS: AIC (Ampere Interrupting Capacity), often written as kAIC for kilo-Amperes, is a specific rating for protective devices that open a circuit, such as circuit breakers and fuses. SCCR (Short-Circuit Current Rating) is the maximum fault current that a complete piece of equipment or electrical assembly (like an industrial control panel, switchboard, or HVAC unit) can safely withstand without causing a hazard. Electrical calculations should be independently verified before safety-critical work. Ensure the calculated prospective fault current does not exceed the protective device's rated breaking capacity. For additional tools, upgrade to Electrical Tools & Reference, which includes calculators for kVA, Max Zs, cable sizing, and more. Pro Certs Software - trusted by electricians since 2011.
JG Underfloor
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.
- Connect to John Guest thermostats
- Manage timers
- Zone control
- Configure RF systems
- Configure hard-wired systems
- Intuitive user interface
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The JG Underfloor APP is designed to be an easy to use, intuitive solution for connecting to the John Guest range of thermostats and timers. Used for both RF and hard wired systems the app provides the user with ultimate zone control and ease of configuration.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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 September 24, 2026 respectively.
| Parameter | Fault Current Calculator (PFC) | JG Underfloor |
|---|---|---|
| Price | Free | Free |
| Rating | 1.0 (2 ratings) — better | — |
| Positive reviews | 33.3% of reviews — better | 0.0% of reviews |
| Number of ratings | 2 — better | — |
| Update frequency | Every 14 months | Every 14 months |
| Ads | Yes | No — better |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 15.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 10 MB | 177 MB |
| Age rating | 4+ | 4+ |
| Developer | Pro Certs Software Ltd | Reliance Worldwide Corporation aust. Pty. Ltd. |
Customer experience
Fault Current Calculator (PFC)
JG Underfloor
In-app purchases
Fault Current Calculator (PFC)
No in-app purchases
JG Underfloor
No in-app purchases
Questions
Is Fault Current Calculator (PFC) free?
Is JG Underfloor free?
Do Fault Current Calculator (PFC) or JG Underfloor have ads?
Which is updated more often, Fault Current Calculator (PFC) or JG Underfloor?
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