Max Zs Values

Max Zs Values

Zs Values 18th Edition BS 7671

0 ratings
29 reviews
$9.99

Price history


Details

  • Released
  • Updated
  • February 12, 2012
  • July 29, 2025

Features

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About

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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What's New in Max Zs Values

3.1.18

July 29, 2025

29/07/2025 v3.1.18 - UI improvements. - In-app optimisations.

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User reviews

Unhappy long standing customer

Really unhappy that I have purchased this app previously at nearly £10 - had it for years, used it often. Purchased a new phone and I’ve had to repurchase it. Even though I’ve used the same email address to repurchase. I feel like that is unfair.

Rip off

Really poor app

Essential for commissioning.

I have had this app for a few years and the update is amazing!!!! Everything is always up to date, easy to use l. has many variety of MCB, fuses and MCCBs values available.

Well done to whoever made it.

Insightful

No, not Mccb’s but type 4 3871.
Seeing that you had the Mccb’s gave me hope for the 3871’s
Other than that it’s a great app.
Bad mood, sorry for the gut reaction.

Cert Time Saver

Brilliant app. Saves valuable time when fillling out certs especially for MCCB max zs. Awesome.

Developer apps

FAQ

What does the Max Zs Values app do?

The app calculates and allows you to look up the maximum permitted Zs value (earth loop impedance) for electrical installations. It is based on the 18th Edition of BS 7671 and includes important adjustments and data for accurate safety assessments.

What are the key features of this app?

Key features include 100% BS 7671 Zs values, 80% On Site Guide Zs values, support for various disconnection times (0.4s, 0.2s, 5s), calculation for common BS EN devices (fuses, MCBs, RCBOs, RCDs), and MCCB manufacturer Zs charts. It also includes a Zs converter for older values.

How much does the Max Zs Values app cost?

Based on the provided information, the app is a paid application. There are no mentions of in-app purchases or advertisements, indicating a one-time purchase model.

Who is the target audience for this app?

This app is designed for electricians, electrical engineers, and anyone involved in electrical installations who needs to ensure compliance with BS 7671 safety standards. It's particularly useful for calculating and verifying earth loop impedance values.

What are the common use cases for this app?

Common use cases include calculating the maximum permitted Zs value for specific protective devices and ratings, checking compliance with different disconnection times, looking up manufacturer-specific Zs data for MCCBs, and converting older Zs values to the current 18th edition standards.