Electrical Voltage Classification
On the basis of different criteria, we can classify electrical voltages into many classes based on different standards. Then, below table is a general classification of voltage classes and range:
IEC 60038: IEC standard voltages:
In many discussions on the classification of AC Voltages, like ELV, LV, MV, HV & EHV, we can get:
| IEC voltage range | AC RMS voltage (V) | DC voltage (V) | Defining risk |
|---|---|---|---|
| High voltage | > 1 000 | > 1 500 | Electrical arcing |
| Low voltage | 50 to 1 000 | 120 to 1 500 | Electrical shock |
| Extra-low voltage | < 50 | < 120 | Low risk |
Low Voltage system are power socket, lighting… thus the risk of shock is death.
Moreover, extra low voltage system are CCTV, MATV, Fire Alarm, PA … hence the death risk is low in ELV system.
Other Voltage Ranges
Based on IEC 60038, in its Section-2.
Tables of Standard Electrical Voltage Classification, gives only the following:
-Table 1 – AC systems having a nominal voltage between 100 V and 1 000 V inclusive and related equipment.
-Table 2 – DC and AC traction systems
-Table 3 – AC three-phase systems having a nominal voltage above 1 kV and not exceeding 35 kV and related equipment.
-Table 4 – AC three-phase systems having a nominal voltage above 35 kV and not exceeding 230 kV and related equipment.
-Table 5 – AC three-phase systems having a highest voltage for equipment exceeding 245 kV.
-Table 6 – Equipment having a nominal voltage below 120 V AC or below 750 V DC.
-In fact, in the entire pages of IEC 60038, there is no terminology like Medium Voltage, High Voltage or Extra High Voltage. And the terminology “Low Voltage” is used only once as a foot-note to Table 1 of Section 2, to describe the limits of voltage variation.
-Thus, it is grossly incorrect to quote that IEC 60038 has given the classifications of LV, MV, HV & EHV.
