Manufacturers of enclosures use various safety measures to prevent the risk of electric shocks and to ensure fire resistance of their products. In order to determine the properties of the appliances with regard to the safety of insulation and resistance to fire, the materials from which the cabinets are made have been divided according to the flammability class and the degree of insulation.
Classes of protection of enclosures for electrical appliances
The standard DIN EN 61140 defines four classes of protection against electric shock. Electrical equipment is classified into three groups:
- Insulation class I – conductive elements are protected with basic insulation, which gives users safety in direct contact. The device is grounded with the protective conductor.
- Insulation class II – devices have double or reinforced insulation that provides reliable protection both in direct and indirect contact. Enclosures must not be grounded!
- Insulation class III – systems compliant with this protection class are powered by low voltage (SELV or PELV).
Flammability classes of enclosures
The flammability class of the material informs the user how flame retardant are the materials from which the cabinet for electrical device is made. According to EN 60695-11-10: 2013 [IDT] and IEC 60695-11-10: 2013 [IDT] following classes of reaction to fire exist:
- HB – the sample is ignited horizontally to measure the burning rate in mm/min (HB75, HB40).
- V2 – the sample is mounted vertically, the material self-burns after max. of 30 seconds. Flaming material may drip.
- V1 - the sample is mounted vertically, the material self-burns after max. of 30 seconds. Incandescence is allowed for max. 60 seconds. No flaming material is allowed to drip.
- V0 – the sample is mounted vertically, the material self-burns after max. of 10 seconds. The sum of the ignition and incandescence times for all samples must not exceed 30 seconds. No flaming material is allowed to drip.
The flammable properties of polymers are related to their heat release capacity (HRC). The polymers that we use in our in our products are classified to V0, group of materials with the best non-flammable properties.