Max Zs Values vs SpanSet
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Max Zs Values
This app calculates and displays maximum permitted Zs values for electrical installations, adhering to the 18th Edition of BS 7671. It includes 80% temperature adjusted values and manufacturer charts for MCCB devices, along with a converter for older Zs values.
- 100% BS 7671 Zs Values
- 80% On Site Guide Zs Values
- Adjustable disconnection times (0.4s, 0.2s, 5s)
- BS EN Device Zs calculation
- MCCB 60947-2 Zs charts
- Zs Converter for 18th edition
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Calculate and look up the maximum permitted Zs value ( earth loop impedance ). Max Zs Values also includes the 80% temperature adjusted values and a some MCCB 60947-2 manufacture Zs charts. - 100% BS 7671 Zs Values - 80% On Site Guide Zs Values - 0.4 (s) second disconnection times - 0.2 (s) second disconnection times - 5 (s) second disconnection times - Common BS EN Devices: Scroll through the list of protective devices and select the device rating to calculate the maximum permitted Zs value for your selected protective device and rating combination. - 60947-2 MCCB's Zs Tables: Look up the maximum permitted Zs tables for a selection of MCCB manufacture devices (some). - Maximum Zs Features: + Maximum Disconnection Times + BS 7671 18th Edition Zs Tables + Fuse's + MCB's + RCBO's + RCD's in TT earthing systems + Max REC Ze values + 100% values + 80% values + 0.4 second disconnection times + 0.2 second disconnection times + 5 second disconnection times + Uo 55v (U 110v) single phase and Uo 63.5v (three phase) Zs values + BS EN 60947-2 MCCB manufacture device charts (some) There is now a new "Zs Converter" to convert old Zs values to the new 18th edition 230v Cmin Zs values. Check out our collection of electrical apps such as the "Pro Certs" Electrical Certification App for iPad.
SpanSet
An interactive guide for inspectors of height safety equipment. It provides detailed information on harnesses, lanyards, and connectors to ensure proper inspection procedures.
- Interactive guide
- Height safety equipment inspection
- Harnesses
- Lanyards
- Connectors
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The SpanSet interactive guide for inspectors of height safety harnesses, lanyards and connectors.
Screenshots
Verdict
The clearest difference is price: SpanSet at Free against Max Zs Values's $9.99. SpanSet also leads on review sentiment (71% vs 55%) and iOS requirement (6.0 vs 11.0). Max Zs Values's advantage is update cadence (every 4 months vs every 27 months). On ads, 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
SpanSet is free to download; Max Zs Values costs $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Max Zs Values ships an update every 4 months, SpanSet every 27 months. The most recent releases landed on October 26, 2026 and October 7, 2026 respectively.
| Parameter | Max Zs Values | SpanSet |
|---|---|---|
| Price | $9.99 | Free — better |
| Positive reviews | 55.2% of reviews | 71.4% of reviews — better |
| Update frequency | Every 4 months — better | Every 27 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 11.0 | 6.0 — better |
| Further details — not scored | ||
| Size | 15 MB | 24 MB |
| Age rating | 4+ | 4+ |
| Developer | Pro Certs Software Ltd | Optical 3D Ltd |
Customer experience
Max Zs Values
SpanSet
In-app purchases
Max Zs Values
No in-app purchases
SpanSet
No in-app purchases
