Low Voltage – LV

Low Voltage – LV

Low voltage is an electrical voltage that is referred to in the consumer segment as the main voltage used for commercial electrical appliances and lighting in homes and industry. Electrical voltages that do not exceed the specified limit values ​​are referred to as low voltage. Electrical safety codes define “low voltage” circuits that are exempt from additional protection required at higher voltages. These definitions vary by country and specific codes or regulations. Low voltage represents a significant risk of electric shock, which must be minimized by technical measures ( insulation, closure, grounding), but a small risk of electric arc in the air. The term low voltage is used to distinguish it from high voltage, which requires a higher degree of protection.

• According to the ANSI C84.1-2020: low voltage is between 240 to 600 V.
• According to the IEC: low voltage is the voltage between 50 – 1,000 volts of alternating current and between 120 – 1,500 V of direct current.

Classification of Voltage Levels

The electric power can be generated, transmitted, and utilized in different voltages. We must note that different definitions are used in electric power transmission and distribution compared with electronics design. In addition, different voltages and different grid frequencies are used in the world. In the United States, the National Electrical Code (NEC) and the National Electrical Manufacturer’s Association (NEMA) have guidelines and standards that cover all voltage classifications. The American National Standards Institute (ANSI) oversees the creation, promulgation, and use of thousands of guidelines and standards that affect businesses.

NOTE: This page is for informational use only. Always consult with a certified professional when designing and working on electrical equipment. Never work on energized circuits or perform duties that you are not qualified for.

Classification of Voltage Levels- ANSI

In the United States, the American National Standards Institute (ANSI) establishes nominal voltage ratings for 60 Hz electric power systems over 100 V. Specifically, ANSI C84.1-2020 defines:

• low voltage as 240 to 600 V
• medium voltage as 2.4 to 69kV
• high voltage as 115 kV to 230 kV, 
• extra-high voltage as 345 kV to 765 kV, 
• and ultra-high voltage as 1,100 kV.

Classification of Voltage Levels – BS 7671

British Standard BS 7671:2008 defines high voltage as any voltage difference between conductors that is higher than 1000 VAC or 1500 V ripple-free DC, or any voltage difference between a conductor and Earth that is higher than 600 VAC or 900 V ripple-free DC.

Classification of Voltage Levels- IEC

In the context of building wiring and the general use of an electrical apparatus, the International Electrotechnical Commission defines:

• high voltage as more than 1,000 volts (V) of alternating current (AC) and above 1,500 V of direct current (DC). 
• low voltage as the voltage between 50 – 1,000 volts of alternating current and between 120 – 1,500 V of direct current.
• extra-low voltage as lower than 50 V of alternating current and 120 V of direct current

110V vs. 220V – Where and Why – Difference

The difference is that the higher the voltage, the more power can be available with the same amperage as with a low voltage. The equation is as follows: Power = Voltage x Current. When 220V wiring is used, less current is required than with 110V wiring. This is the main advantage of 220V. Moreover, 220V is less wasteful. DC power conversion requires less heat at this voltage because there are fewer amps to do the same work.

On the other hand, 110V is considered safer if you get shocked by it due to the fact that your body has a greater chance of resisting the shock at this voltage. It’s true that all things being equal, amps are more dangerous than volts as far as killing you goes, but 220V has a greater chance of pushing those amps into your body than 110V does. Although it’s true that 220V requires less current to provide the same amount of power, 110V can still carry a relatively high current and poses a higher risk of serious injury.

The American continent uses a voltage of 110 to 120 volts (AC) while Europe, Asia, and Africa use 220 to 240 volts (AC). If you’re a frequent traveler, you need to understand how the different voltage increments can affect your devices. However, most travel electronics are rated for dual voltage use and wouldn’t require a converter. When the voltage reading is listed as a range of numbers, like 110V–220V or 100-240V and 50 – 60 Hz, the device can handle AC voltage outlets from all over the world. This is considered a “dual-voltage” or “worldwide voltage” device.

When you’re traveling with dual voltage devices, all you’ll need to pack is your travel adapter. 

Cell phones, tablets, and laptops are typically dual voltage devices, while hair dryers, mixers, and curling irons are typical single voltage devices.

Typical voltages

To help compare different orders of magnitude, the following list describes typical voltage levels.

• 1.5V (DC) – A common open circuit voltage for non-rechargeable alkaline batteries (e.g. AAA, AA, and C cells). 
• 3.8V (DC) – Almost all smartphone batteries work at 3.8 volts. In order to make current flow from the charger to the battery, there must be a potential difference. Therefore battery chargers or USBs for almost all smartphones provide a voltage of 5V.
• 12V (DC) – A common voltage for automobile batteries is 12 volts (DC).
• 110 – 120V (AC) – The most common electrical outlet in any home. The American continent uses a voltage of 110 to 120 volts (AC) while Europe, Asia, and Africa use 220 to 240 volts (AC). 
• 3kV – Voltage required to generate every 1mm of an electric arc. Air is a very bad conductor of electricity and has high dielectric strength. The dielectric strength of air is nearly 3000V/mm.
• 110kV – The voltage in electric power transmission lines used to distribute electricity from power stations can be several hundred times greater than consumer voltages, typically 110 to >500 kV (AC).
• 300 MV – A typical lightning flash is about 300 million Volts and about 30,000 Amps.