Max Zs Values

Maximum permissible Zs values for MCB’s, Fuses and MCCB’s, along with RCD’s and RCBO’s. Earth fault loop impedance values for protective devices.

Electrical Apps for iPhone
Android Electrical Apps
PC Version
max zs values
  • RCBO & RCD Max Zs
  • MCB & Fuses Max Zs
  • MCCB Zs Values
BS 7671 maximum Zs values calculator
Max Zs Values

Protective device maximum Zs values in your pocket.

Optimised for iPad, iPhone, Android Phones and Android Tablets

App Store
Play Store
  • max zs values calculator based on bs 7671

    • MCB’s, RCBO’s and Fuses Max Zs

    • Max Zs > Common BS EN Devices

    The common BS EN devices section contains the most commonly found protective devices.

    Using the Device list select a protective device, using the Rating list select a device rating.

    • BS EN 60898 MCB’s.
    • BS EN 60947-2 MCB’s.
    • BS EN 61009 RCBO’s.
    • BS 3871 type 1, 2, 3 and B, C and D.
    • BS 88 gG, gM and aM cartridge fuses.
    • BS 1362 and BS 1361 (types 1 and 2) cartridge fuses.
    • BS 3036 semi-enclosed fuses.

    BS EN 60947-2 MCCB’s Max Zs

    • Max Zs > 60947-2 MCCB Devices

    This app also contains a selection of BS EN 60947-2 MCCB maximum Zs tables from a variety of manufactures.

    This demo video may not reflect the latest version for the app.

    Demo video
    mccb zs tables
    TT RCD max zs calculator

    Other Sections

    In addition to the max Zs calculator and MCCB Zs tables, there are a few more additional tools and tables included as well.

    • MCCB settings table.
    • Maximum disconnection times table.
    • DNO maximum Ze values.
    • RCD’s in TT earthing systems max Zs.
    • Uo 55v (110v) and 63.5v max Zs values.
    • Max Zs converter, (convert old Zs values to Cmin Zs values).

    What people think about this app…

    • Great App

      Great app to have handy on site. Helps with odd Mccb sizes.
      Keith Fredericks
      Android

    • Amazing!!!!

      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.
      Tigga man
      iOS

    • Recommended ++++

      Useful app, saves thumbing through the regs books. Recommended ++++
      Clive Blunden
      Android

    • Handy pocket guide

      Great app!!! I have been using this app for a few years now and I can not fault it, it’s easy and convenient to use and rather than having to overthink and take you away from the everyday job it saves time.
      Ryan ‘hamster’ Hamdy
      iOS

    • Very useful

      Found this app very useful for getting mccb’s disconnection times
      martin henningham
      Android

    Summary of Features

    • Fuses max Zs
    • MCBs max Zs
    • RCBOs max ZS
    • RCD Max Zs for BS EN 61009, 61008, BS 7288, BS 4293 and BS 7071 in TT systems
    • MCCB max Zs tables
    • Pre Cmin Zs values converter
    • DNO max Ze
    • 110V (Uo 55V) max Zs
    • TT earthing system max Zs values

    Max Zs values for all common (and some not so common) protective devices.

    Get the App

    Download the Max Zs Values app to start looking up your protective device Zs today.

    Electrical Apps for iPhone
    Android Electrical Apps
    PC Version