Low voltage vs high voltage

There are two different voltage ranges. Low voltage and high voltage. Surprisingly some electrical professionals do not know the differences between them. Below I compare these two voltage ranges and give you the differences between them.

Differences between low voltage and high voltage

The followings are the differences between low and high voltage.

Definitions

According to ANSI C84.1-1989 and IEE 141-1993 standard, voltages 600 V and below are referred to as low voltage. According to IEC 60038 voltages, 1000 VAC and below are referred to as low voltage.

Note: The 2014 National Electrical Code has ushered in a change to the definition of low voltage. The NEC elevated the maximum voltage threshold for this category from 600 V maximum to 1000 V maximum. This was done to accommodate the growing solar market where voltages up to 1000 V are becoming more commonplace.

According to ANSI C84.1-1989 and IEE 141-1993 standard, voltages from 600 V-69 kV are referred to as medium voltage.

According to ANSI C84.1-1989 and IEE 141-1993 standard, voltages from 69 kV-230 kV are referred to as “high voltage” and voltages 230 kV-1,100 kV are referred to as “extra-high-voltage,” with 1,100 kV also referred to as “ultra-high voltage.” According to IEC 60038 voltages above 1000 VAC are referred to as “high voltage,”

Usage areas

Low voltage can be used in most domestic, commercial, and industrial applications. Plugs, sockets, lighting, heating, home appliances can be supplied with low voltage in domestic applications. The typical home has wiring in the 100 to 240 VAC standard. Commercial examples of low voltage are fire alarms, sound systems, security systems, control and communication systems.

The high voltage range is where you will find the overhead distribution networks or specialized industrial applications. It is also used in cathode ray tubes, to generate X-rays and particle beams, to produce electrical arcs. (Landmark chemistry and particle physics experiments and discoveries.)

Transmission

Electricity is transmitted with high voltage. The reason for transmitting with high voltage is to increase efficiency. Entry to the high voltage area will be strictly restricted and controlled. Using transformers high voltage can be reduced to low voltage for home-usage.

Danger and arc generation

High voltage is more dangerous than low voltage because it carries a higher degree of voltage. High voltage is classified as having the potential to cause injury or harm. The high voltage generates more electrical arc in a possible arc fault and it is extremely dangerous for the people and the systems. High voltage electrical discharges can produce small quantities of toxic gases, which can be a health hazard.

Remember: Low voltage is also dangerous for everybody. It is only called low voltage because it is a lower voltage compared to high voltage. But low voltage is easy to control compared to high voltage.

Cables and equipment

The diameters of high voltage cables are bigger than low voltage cables. Besides, high voltage equipment such as motors, breakers, isolators is much bigger in size compared to low voltage equipment. High voltage equipment should be isolated carefully.

Cost

The cost of high voltage equipment and switchgear is more expensive than low voltage equipment and switchgear.

Voltage ranges according to ANSI C84.1-1989 and IEE 141-1993 standard

Voltage ranges according to IEC 60038 standard

Standard IEC 60038 defines a set of “standard” voltages to be used for creating AC and DC power and it refers to two voltage ranges: LV and HV.

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