Calculation of Maximum and Minimum Short-circuit Currents
The calculation of maximum and minimum short-circuit currents as per IEC 60909 is based on the following assumptions. No change in the type of short circuit involved, that is, a …
Determining the required sizes of earthing conductors and earth electrodes
The sizes of earth conductors and earth electrodes are almost always chosen from typical sizes as provided by a particular project standard. If using non-typical sizes can extensively impact the …
IEC Equipment Voltages
There are two (2) voltage levels used in IEC, low voltage ( < 1000 V ) and high voltage ( > 1000 V ). Medium voltage, inspite being oftenly used …
Resistance of Earth Electrodes in Parallel
In previous articles Single Earth Electrode and Earthing Resistance Calculation, I have presented methods of calculating the earth resistance using IEEE or IEC methods. AS 1768 Appendix C recommends that …
Resistance of a Single Earth Electrode
The resistance of a single earth can be calculated if the soil resistivity is known. An earth rod driven vertically, the electrode resistance can be calculated using the following formula. …
Isolation of Neutral Conductor in Hazardous Areas
IEC 60079-14 (2007) Clause 8.2 Electrical isolation, states that: To allow work to be carried out safely, suitable means of isolation (for example isolators, fuses and links) shall be provided …