What Is a Class 1 Electrical Equipment? Symbol, Example

Class 1 electrical equipment – equipment with at least one provision for basic protection and with means for protective-equipotential-bonding for fault protection [defined in the IEC 60050-195:2021].

Electric kettle is an example of class 1 equipment
Electric kettle is an example of class 1 equipment

Co-ordination between electrical equipment and protective provisions within an electrical installation.

The use of protective provisions for class I equipment is described below (see also Table 3 [1]):

Class of equipmentEquipment marking or instructionsSymbolConditions for connection of the equipment to the installation
Class IMarking of the protective bonding terminal with graphical symbol IEC 604175019:2006-08, or letters PE, or colour combination green-yellowClass 1 Equipment SymbolConnect this terminal to the protectivee-quipotential-bonding system of the installation
Table 3 – Application of equipment in a low-voltage installation

Insulation

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. This also applies to conductive parts which are separated by basic insulation but which are connected to hazardous-live-parts through components which are not designed for the same stresses as specified for basic insulation.

Connection to the Protective Conductor

Exposed-conductive-parts of the equipment shall be connected to the protective conductor terminal.

NOTE. Exposed-conductive-parts include those parts which are covered only by paints, varnishes, lacquers and similar products.

Conductive parts which can be touched are not exposed-conductive-parts if they are separated from hazardous-live-parts by protective separation.

Accessible Surfaces of Parts of Insulating Material

If the equipment is not completely covered with conductive parts, the following applies to accessible parts of insulating material:

Accessible surfaces of parts of insulating material which:

  • are designed to be grasped, or
  • are likely to come into contact with conductive surfaces which could distribute hazardous potential, or
  • can come into significant contact (area more than 50 mm × 50 mm) with a part of the human body, or
  • are to be used in areas where the pollution is highly conductive,
  • shall be separated from hazardous-live-parts by:

– double or reinforced insulation, or
– basic insulation and protective screening, or
– a combination of these provisions.

All other accessible surfaces of parts of insulating material shall be separated from hazardous-live-parts by at least basic insulation. For equipment intended to be part of the fixed installation, the basic insulation shall be provided either by the manufacturer or during installation as specified by the manufacturer or responsible vendor in his instructions.

These requirements are deemed to be complied with if the accessible parts of insulating material provide the required insulation.

Technical committees may impose more stringent requirements than basic insulation for certain accessible parts of insulating material (e.g. which need to be touched frequently, such as operating means), taking into account the area of the contact surface with the human body.

Connection of a Protective Conductor

The means of connection, except for plug-and-socket connections, shall be clearly identified either with the graphical symbol IEC 60417-5019:2006-08, or with the letters PE, or by the bi-colour combination of green and yellow according to IEC 60445. The indication shall not be placed on or fixed by screws, washers or other parts which might be removed when conductors are being connected.

For flexible cable connected equipment, including fixed and plug-and-socket types, provisions shall be made such that the protective conductor in the cord shall, in case of failure of the strain-relief mechanism, be the last conductor to be interrupted.

References

  1. IEC 61140-2016