To protect persons or system from the effects of electrical operating voltages, especially in the case of malfunction of equipment, sufficient measurement of the clearance and creepage distance is required.
For safety reasons and for every certification (IEC, UL, CSA) it is essential that certain clearance and creepage distances are maintained. In the following you find further explanations and information on determining clearance and creepage distances.
Clearance distance - shortest separation in the air between two conducting parts
Creepage distance - shortest separation along the surface of an insulating material between two conducting parts
Determination in accordance with IEC:
The rated impulse voltage, critical for the dimensioning of the clearance distance, results from the overvoltage category and the conductor - earth voltage derived from the nominal mains voltage (taking all mains types into consideration).
The minimum clearance distance (up to installation heights of 2000 m above sea level) is determined from the rated surge voltage and the pollution severity.
A detailed overview of the calculation of the clearance and creepage distance is available as a download.