Friday, April 19, 2019


The Equipment Classes Considering the Insulation Level to Protect Electrical Shock

It is almost impossible to go the end of a list where electricity is necessary in our life today, and we everybody will agree that electricity is the closest friend in our daily-life.
Yes, electricity is very close friend and helping us every moment; but don’t forget, it will make no mistake to injure you even to kill by shock if you are not alert before it getting the chance.
Bearing in mind the electrical shock, a safety measure must ensures in our electricity operated home appliances and equipment. Electricity shock protection procedures are different depending on the tentative shock level.
Considering the electric-shock preventive insulation level the equipment are classified on three types as follows:

Electrical Safety
  • Class-I Equipment;
  • Class-II Equipment;
  • Class-III Equipment.

Class-I Equipment

The electrical equipment which includes a means for connection of Exposed Metallic Parts (EMP) of the equipment to the Earth Conductor (EC) to provide protection against electric shock in case of failure of the basic insulation of the equipment or other fault condition.
Simply, the equipment which body is earthed or connected to the ground or earth through earth conductor is known as Class-I Equipment.
In this case if electrical connection go wrong and equipment body become electrified then connected earth wire drain down the current to ground and protect from dangerous electric shock if touch the equipment anyone.
The equipment like electric-heater, electric motor, electric iron etc. are under Class-I equipment.

Class-II Equipment

The electrical equipment which does not include a means for connection to an Earth Conductor (EC), but provides supplementary insulation in addition to the basic insulation of the equipment is known as Class-II equipment. This equipment also known as double insulated equipment.  
The equipment like electric hair-drier, electric hair trimmer etc. are under Class-II equipment.
To get details specifications for Class-II Equipment you can check in British Standard BS2754.

Class-III Equipment

The electrical equipment in which protection against electric shock relies on supply at Separate Extra Low Voltage (SELV) system is the source of power that shall not exceed extra low voltage (50V ac or 150V dc) between conductors or to earth, also  the voltages higher than SELV are not generated in the equipment is known as Class-III Equipment.
To get more details about Class-III equipment you can check British Standard BS2754.
Bathroom wiring and water pool wiring is followed ELV and SELV system.

Considering over all insulation level the equipment are classified on five types as follows:

  • Class 0
  • Class I
  • Class 0I
  • Class II
  • Class III
Where Class I, II & III already described, now we will explain the Class 0 and 0I:

 Class 0: The appliances those have no any protective-earth connection and used only a single level of insulation between live parts and exposed metallic parts for safety purposes. This Class 0 equipment is produced to use only for dry area, not for in wait weathered area. A single fault may cause a major electric shock or dangerous damages man or property without using the automatic operation of any fuse or circuit breaker. The country like UK  and New Zealand has prohibited to sale such insulation class equipment by their law. Only 110 V using countries are allow to use this class of equipment other wise most of 220 V using developing countries are using this Class 0 equipment,whether permitted officially or not.

Class 0I: Where the chassis of equipment is connected to earth with a separate terminal, not via the mains cable; that type of electrical equipment is described as Class 0I insulation equipment.The effect in this case provides the same automatic disconnection as Class I, for equipment that otherwise will be Class 0.


Hope the that made sense about 'The Equipment Classes Considering the Insulation Level to Protect Electrical Shock', if you have more information to share others. You may put below.

01. IEC 61140: Protection against electric shock — Common aspects for installation and equipment. International Electrotechnical Commission. 2001. (formerly: IEC 536-2: Classification of electrical and electronic equipment with regard to protection against electric shock, 1992);
02. BS 2754 : 1976 (1999): Memorandum. Construction of electrical equipment for protection against electric shock;
03. Wikipedia, https://en.wikipedia.org/wiki/Appliance_classes;

04. WAZIPOINT, wazipoint.blogspot.com

1 comment:

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