What Is a Class 2 Electrical Equipment? Symbol, Examples

Class 2 electrical equipment – electrical equipment where basic protection and fault protection are provided by double insulation or reinforced insulation [defined in the IEC 60050-195:2021].

The definition given gives a general description of Class II electrical equipment from the point of view of providing protection against electric shock during its operation. Live parts of Class II electrical equipment must have basic insulation which provides basic protection and additional insulation which provides fault protection. That is, Class II electrical equipment must have double insulation or the equivalent reinforced insulation which provides both basic protection and fault protection.

With Class II electrical equipment, protection against electric shock involves the use of protective provisions used to provide basic protection and fault protection.

Class II electrical equipment has basic and supplementary insulation (i.e. double insulation) or reinforced insulation of its hazardous-live-parts. Touchable conductive parts of the specified electrical equipment, if any, are not connected to the protective conductors of the electrical installation of building in order to provide protective earthing.

Under normal conditions, when the double or reinforced insulation is intact, the hazardous-live-parts of Class II electrical equipment must not be touched. Hazardous-live-parts cannot be short-circuited to touchable conductive parts of class II electrical equipment. Therefore, touchable conductive parts are not live and do not present a hazard to humans or animals.

Under single fault conditions, when the basic insulation of a live or partially hazardous-live-part has been faulted, the extra insulation and the intact part of the reinforced insulation prevent an electrical connection between that live part and the touchable conductive part of Class II electrical equipment. Therefore, no voltage that would be hazardous to humans or animals can appear on the touchable, conductive part.

Thus, basic protection and protection against damage are provided by the protective provisions that are implemented in Class II electrical equipment. No additional electrical protective measures are therefore necessary when Class II equipment is used in the electrical installations of buildings.

Class 2 Electrical Equipment Symbol & Marking

Class II equipment, including equipment complying with 7.4.3.1, shall be marked with the graphical symbol of IEC 60417-5172:2003-02, placed adjacent to the supply information, e.g. on the rating plate, in such a way that it is obvious that the symbol is part of the technical information and can in no way be confused with the manufacturer’s name or other identification marks.

Where a class II equipment has a functional earthing terminal, this terminal shall be identified with the graphical symbol IEC 60417-5018: 2011-07.

Table 3 of IEC Standard [2] requires that Class II equipment be marked in the above way (double square). The conditions for connecting Class II electrical equipment to a low-voltage installation, as specified in this table, do not depend on the protective measures used in the installation.

Class of equipmentEquipment marking or instructionsSymbolConditions for connection of the equipment to the installation
Class IIMarking with the graphical symbol IEC 60417-5172:2003-02 (double square)IEC-60417-5172-2003-02 (double square)No reliance on installation protective measures
[Table 3 IEC 61140-2016] – Application of equipment in a low-voltage installation

Class 2 Electrical Equipment Examples

Class II electrical equipment is widely used in electrical installations of buildings, especially in those rooms characterized by an increased risk of electric shock. The use of class II electrical equipment in such conditions provides a higher level of electrical safety than when using class I electrical equipment. Class II hand-held electrical equipment, such as power tools, is widely used.

Screwdriver as an example of class II portable electrical equipment
Figure 1. Screwdriver as an example of class II hand-held electrical equipment

Examples of class two appliances include things such as DVD players, portable CD, radio cassettes players, hair dryers, TVs, lawnmowers, computers, photocopiers, plug-top power supplies, table lamps.

Class 2 Electrical Equipment Requirements

Requirements for Class II equipment are set out in clause 7.4 of the standard [2].

Insulation

The accessible conductive parts and the accessible surfaces of parts of insulating material shall either be:

  • separated from hazardous-live-parts by double or reinforced insulation, or
  • designed with constructional arrangements providing equivalent protection, e.g. a protective impedance device.

For equipment intended to be part of the fixed installation, this requirement shall be fulfilled when the equipment is properly installed. This means that the insulation (basic, supplementary or reinforced) and the protective impedance, if relevant, shall be provided either by the manufacturer or during installation as specified by the manufacturer or responsible vendor in his instructions.

Arrangements providing equivalent fault protection may be defined by technical committees along with requirements appropriate to the nature of the equipment and its application.

All conductive parts which are separated from hazardous-live-parts by basic insulation only or by constructional arrangements providing equivalent protection shall be separated from the accessible surface by supplementary insulation or by constructional arrangements providing equivalent protection.

All conductive parts which are not separated from hazardous-live-parts by at least basic insulation shall be treated as if they were hazardous-live-parts, i.e. they shall be separated from the accessible surface.

The enclosure shall not contain any screws or other fixing means of insulating material where these screws or other fixing means need to be removed or are likely to be removed during installation and maintenance and where the replacement of which by metallic screws or other fixing means could impair the insulation required.

The insulation of class II equipment shall comply with 5.1.6 of IEC 60664-1:2007.

Protective Bonding

Class II equipment shall not have a provision for connection to a protective conductor except for applications according to 7.4.3.2 [2]. Here is the full content of clause 7.4.3.2:

Where a class II equipment is provided with means for maintaining the continuity of a protective conductor, but in all other respects is constructed as class II equipment, such means shall be insulated in accordance with 7.4.2.1 [2].

7.4.3.2 [2]

Conductive parts enclosed in the insulating enclosure shall not be connected to a protective conductor. However, provision may be made for connecting protective conductors which run through the enclosure. Inside the enclosure, any such conductors and their terminals shall be insulated as though they were live parts, and their terminals shall be marked as PE terminals.

7.4.3.2 [2]

Class II equipment may be provided with means for connection to earth for functional (as distinct from protective) purposes only where such a need is recognized in the relevant IEC standard. Such means shall be insulated from live parts by double or reinforced insulation. The means for functional earthing shall have a distinctive marking from the means for protective earthing and shall not be connected by a conductor identified as PE in accordance with IEC 60445.

References

  1. IEC 60050-195:2021
  2. IEC 61140-2016