A question about whether the second part of clause 21.2 needs to be tested.

Byforest

We know that clause 29.3.2 and clause 21.2 are two separate clauses and they are not very much related, which means that the product being assessed needs to fulfill both clauses if applicable.A reinforced insulation system consisting of three separate layers of insulating material or what could be considered a double insulation system, Each layer…

Clause 3 – How to understand the definition of “safety extra-low voltage”

Byforest

safety extra-low voltage: voltage not exceeding 42 V between conductors and between conductors and earth, the no-load voltage not exceeding 50 V When safety extra-low voltage is obtained from the supply mains, it is to be through a safety isolating transformer or a convertor with separate windings, the insulation of which complies with double insulation…

Clause 3 – How to understand the definition of “class II construction”

Byforest

The emphasis here is on a part of the construction on the appliance, which can meet the requirements of double insulation or reinforced insulation. Therefore, a class I appliance will also contain a class II construction .Example: The oven shown in the figure below uses a metal shell and a plastic switch knob. When the…

Clause 3 – How to understand the definition of “class II appliance”

Byforest

class II appliance: appliance in which protection against electric shock does not rely on basic insulation only but in which additional safety precautions are provided, such as double insulation or reinforced insulation, there being no provision for protective earthing or reliance upon installation conditions. NOTE 1 Such an appliance may be of one of the…

Clause 3 – How to understand the definition of “reinforced insulation”

Byforest

reinforced insulation: single insulation applied to live parts, that provides a degree of protection against electric shock equivalent to double insulation under the conditions specified in this standard.NOTE It is not implied that the insulation is one homogeneous piece. The insulation may comprise several layers which cannot be tested singly as supplementary insulation or basic…

Clause 3 – How to understand the definition of “double insulation”

Byforest

double insulation: insulation system comprising both basic insulation and supplementary insulation The definition is only to simplify the description of basic insulation and supplementary insulation in the standard, using one name to descirbe two names. As shown in the figure below, the supply cord has two layers of insulation, the inner wire sheath and the…

Clause 3 – How to understand the definition of “supplementary insulation”

Byforest

supplementary insulation: independent insulation applied in addition to basic insulation, in order to provide protection against electric shock in the event of a failure of basic insulation An insulation that is outside the basic insulation and is independent of the basic insulation, and is usually accessible to the user. Supplementary insulation, as the name implies,…