Clearance and creepage distances

Extracts from DIN VDE 010-04.97

Clearances shall be dimensioned according to the following circumstances: The dimensioning has to be made in view of the expected overvoltages, taking into consideration the protective measures against overvoltages and pollution. For the dimensioning of clearances the rated impulse voltages in table 01.00 are appropriate. They derive from the overvoltage category and from the nominal net voltage. The overvoltage categories are defined as follows:

Overvoltage category I
Overvoltage category II
Overvoltage category III
Overvoltage category IV

For dimensioning of minimum clearances the rated impulse voltage and the degree of pollution have to be taken into consideration. We distinguish between the following degrees of pollution:

Degree of pollution 1
Degree of pollution 2
Degree of pollution 3
Degree of pollution 4

The rated impulse voltage and the degree of pollution are necessary to determine the minimum clearances and can be taken from table 00.2a .

Creepage distances

For dimensioning of creepage distances the rated voltages acc. to table 00.03a / 00.03b depending on the relevant kind of net have to be determined.

The different degrees of pollution defined for the clearances apply also to the creepage distances.

Taking into consideration the degree of pollution and the insulation material the minimum creepage distance is taken from table 00.04 .

The creepage distance is defined as the shortest distance along the surface of the insulation material between two conductive parts. This insulation material be suitable for continuous voltage load.