There are different electrical systems-based voltage, types of current, frequencies, and other factors.

In this article Can Electrical Ltd, electrical service department will give you brief information about each of those systems and their main functions and applications.

  • Based on Voltage:
  • Low voltage (CEC2018-Sec-26-235)
  • Medium voltage (CEC2018-sec-26)
  • High voltage/ Extra high voltage (CEC2018- Sec36)
  • Ultra-high voltage (CEC2018-Sec36)


  • Current Types:
  • AC (CEC2018-12-2110)
  • DC (CEC2018-10-200)


  • Frequencies: (CEC2018-60-704)
  • 50 Hz system
  • 60 Hz system
  • Custom frequency systems


Can Electric ltd, our Edmonton electrical service department provide efficient and professional electrical services with Edmonton electricians for all types of electrical systems, please feel free to contact us for a free estimate.

Electrical systems based on voltage

Voltage is electrical charge (energy potential) which is generated in the form of power and its measured with v (volts). (V= W/I). This classification is done to make electricity generation, transition and consumption most efficient and safe as following 4-levels:

  • Low voltage
  • Medium voltage
  • High voltage/ Extra high voltage
  • Ultra-high voltage


Low voltage (LV)

It’s (12V-to-600V), called utilization voltage used at the end points for power usage, equipment’s, appliances, and lighting and other purposes and it is secondary distribution lines and connected to the main utility transmission lines with main electrical service entrance.

The low voltage distributed to residential buildings is 120V to 240V volts and the low voltage distributed to commercial buildings is 120/208V to 277/347/480/600V.

Commercial examples of low voltage are fire alarms, sound systems, security system, control and communication systems, regular utility power  and residential examples are doorbells, garage door openers, thermostat, and regular utility power  are examples of low voltage and it has a lot of application in industrial.


Medium voltage (MV)

It’s the voltage range between (0.6KV to 36KV and in some systems it goes up to 110KV), which is altered and changed by using of transformers, this voltage level is mostly used for primary distribution lines.


High voltage (HV)/ Extra high voltage (EHV)

Its standard transmission voltage in both forms of AC and DC and it starts from 110KV to 800KV. most transmission networks voltage is 110KV and higher. HVDC recently has become very important and essential to large and long-distance power transmissions.


Ultra-high voltage (UHV)

It is power transmission voltage and it starts from 800KV and up.

Note: this classification might be different in different countries and for different applications and the terms “MV” and “HV” have been interchangeably used based on standard and electrical code and regulations. for example, according to CEC anything above 750V is considered high voltage.

Our Edmonton electricians will provide electrical service based on your systems voltage, to best serve you and your business, contact electricians in Edmonton for your electrical system upgrade and evaluations.

Electrical systems based on current types

There are 2-types of electrical currents, AC (alternating current) and DC (direct current), most utility currents that are used for residential and commercial buildings is AC, which is very flexible to change its voltage for transmission and distribution.


Electrical Current

Its flow of electricity from source to point of consumption and its measured and calculated with Ampere, it’s made of moving electrons, which are charged with electromagnetic load (electromagnetic forces) and engage on electricity (I= W/V)


AC current

Its most common electrical current used in power generations, transmissions and distributions for residential, commercial and industrial usage.

It changes direction periodically that causes the voltage level and current direction to change and revers. compare with DC it’s easier to transmit and change the voltage, cheaper to generate, and has lower transmission losses but when the distance is 1000Km or more DC current can be more efficient and have less losses.

Main character of AC current, is that it alternates its directions every 50 seconds on (50 Hz) and 60 seconds on (60 Hz) that create periodic back and forth and this process create current flow from source to electrical load and point of consumption.

Most electrical grids are AC current and including their end users for industrial, commercial and residential applications. and most devices that have an AC adapter built in on them or as accessories that convert alternating current to direct current. Advantage of AC current:

  • Cost effective and cheaper to generate
  • Easy and efficient on voltage changes (step up and step down)
  • Lower maintenance and operation costs in most cases
  • Easier to interrupt and control


DC current

Its one- direction flow of current from source to point of consumption. unidirectional which means that voltage and current magnitude can change but the direction of current flow does not change, and voltage magnitude is most stable and fixed.

Its current that flows in one constant direction which its main difference between DC and Ac currents. you can convert AC to DC by using Rectifiers and DC can be converted to AC by using Inventors. DC is used in most electronic devices including your laptop and computer and in long distance and large amount of power transmission and almost all digital electronics use power in the form of DC.


High-Voltage Direct Current (HVDC)

HVDC It is most efficient ways for power transmission in long distances, but they are more costly compared with AC systems.

Power: Its electricity (voltage and amperage) also called energy and its measured with watt (joules/second) (W=VI)

Electrical systems based on frequencies:

  • 50 Hz system
  • 60 Hz system
  • Custom frequency systems

What is frequency?

Its AC current alteration to number of cycles per second in the form of sin waves it also when current changes its directions per second or complete a its cycle in a second and its measured by Hertz (Hz) and every Hz is equal to one cycle per second and it is called after German physicist (Heinrich Rudolf Hertz) because he was the first person  that discovered radio waves.

It’s important to know that frequencies that are discussed here are utility frequencies which are being used for power and called utility or grid frequencies.

Only AC has frequency or oscillations and the most common frequency in the world is 50 Hz, except in America and part of Asia it is 60Hz and these two frequencies are standardized for utility power all over the world. and with these two main frequencies each come with special end point distribution power voltage which is 100-to-120 volts for 60Hz and 220-240 volts for 50Hz.

Some countries like Japan use both frequencies. and systems frequency can change based on its load when the load is high the frequency will decrease and when electrical system is operating in lower load the frequency will increase. this fluctuation is very small and not noticeable on stable power systems.

Another difference between 50 Hz and 60 Hz is the speed of generator or induction motor that the power is generated from. for example, when frequency of power generated is 50Hz, the RPM will be 1500 and 60Hz will need 1800 RPM. The equipment used to help use 50Hz equipment with 60 Hz is called VFD.


Custom frequency systems

This is frequency that is used in stand-alone systems and they are not connected to larger grids and power distribution networks. for examples some ships, airplanes might use 300, 400, or 500 Hz systems.

Our Edmonton electrical service department offer timely and professional electrical services for all your electrical needs please contacts us for free electrical consultation and estimates by our Edmonton electricians.

Electrical Terms:

  • IEEE: Institute of Electrical and Electronics Engineers
  • IEC: International electrotechnical commission
  • CEC: Canadian Electrical Cod
  • LV: Low voltage
  • MV: Medium voltage
  • HV: High voltage
  • EHV: Extra high voltage
  • UHV: ultra-high voltage I: Current (Amperage)
  • P: power (wattage)
  • V: volt (voltage)
  • R: resistance (Ohms)
  • Hz: Hertz
  • KVA: kilovolt-ampere
  • RPM: Revolutions per minute
  • VFD: Variable Frequency Drive





IEC (International electrotechnical commission)

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