Earthing tab contains earthing parameters associated with the system and has three sections:

  • Earthing conductor

The user can define an earthing conductor by ticking the use tick box and selecting a cable type, an installation method, a cross-section area by using the associated drop-down lists. In case of a parallel arrangement, number of conductors can be set by using the up and down arrows next to Parallel text box. The length can be modified by typing in the required length into the Length text box in metres.

ElectricalOM will display the tabulated current carrying capacity and impedance parameters of the conductor below the settings.

    • Earthing conductor size check

ElectricalOM can check the size of the earthing conductor either based on the Adiabatic equation or based on Table 54.7 of the BS7671. The user can select the required option by using the radio buttons next to each option.

  • Resistance of the earthing electrode (Ω)

ElectricalOM has a built in earth electrode resistance calculator. Although it is a basic calculator and not intended for complex earthing arrangements, it may help the user to estimate the earth resistance electrode in case of a simple installation. The user can select the electrode type and ground type using the drop-down lists, and define required parameters by typing in the values into the text boxes. ElectricalOM will calculate the resistance and display it below.

This value will contribute to various parameters of a TT system and affect the disconnection times during an earth fault.

Once all the parameters are set, ElectriclaOM will display the earth fault current at the origin, at the bottom of the window.

  • Main protective bonding conductor

The user enable and define a main protective conductor by using the Use tick box and the drop-down list. ElectrcialOM has a guidance window for reference, this can be access by clicking on the Guide link. The earthing system can be selected by using the tabs.

In case of TN-C-S system, the user can select the required conductor size directly by clinking on one of the links.