Electrical power is generated at a very high voltage and is then transformed along the UK power distribution network into lower voltages that we connect to for everyday purposes. High and low voltages are essentially different forms of electricity and are used for different applications which are largely commensurate with the requirement for powering large and small devices. This is one key difference between low and high voltages, but there are many others.
What is high voltage?
High voltage can be defined as a form of electricity that has high potential energy and is used for powering large devices such as industrial machinery. High voltage systems are more dangerous if not handled correctly and therefore require stricter safety control measures. As you would expect, there is more energy required to produce high voltages, so they are more expensive to produce than low voltages. Typical applications for high voltages include power generation, transmission, distribution applications, and equipment such as motors and transformers. You would typically see high voltages used in factories and production plants, sub-stations and power plants.
What is low voltage?
Low voltage is a form of electricity with lower potential energy than high voltage. Low voltage will typically power small devices like a radio or a toaster, or in an industrial environment, a hand tool such as a hand grinder. So, devices using low voltage are less dangerous, but at the same time are less powerful. You see low voltage systems in automotive vehicles and in telecommunications, but also in audio visual equipment, security systems and household appliances.
What voltage ranges are low and high voltage?
There are different definitions of this, but a widely accepted indication of each form of electricity is:
- Low voltage – Anything from 0 to 1000 volts
- Medium voltage – 1001 volts to 45 kV
- High voltage – 45 kV to 230 kV
Other differences between low voltage and high voltage
Safety – The higher the voltage in a wire or cable, the more intense the energy is, so low voltage electricity is less likely to cause damage or injury to a person, but the user should still ensure that basic safety precautions are made, and an item or equipment is safe to use, ie. an item has been PAT tested, or an installation has been tested and inspected, and there are no damaged or exposed wires. High voltage wires and cabling are more dangerous due to the intensity of the electricity, so you should take the same precautions as above, but should also wear appropriate personal protective clothing to avoid all contact with the electrical current.
Arcing – High voltage can cause arcing, which is when electricity jumps from one conductor to another due to gaps in the electrical path, or the voltage is too high for the system. Arcing can cause explosions and fire, but only occurs with high voltage, not with low voltage.
Cabling – Low voltage cabling tends to be thinner and easier to install. Think about a mobile phone charging cable or a laptop cable, compared to the thick and robust, heavy-duty cabling used for large electrical panels or an EV charger, for example. This makes low voltage systems much easier to install and therefore much cheaper.
Please note that this section is for information purposes only. Anyone using equipment referred to in this section must be suitably qualified and/or experienced within the respective field. If in doubt before use, please consult a qualified electrician or engineer & thoroughly read all instruction booklets.