scope:

This report deals with the Co-ordination of insulation in low-voltage installations including clearances and creepage distances for equipment, bearing a rated voltage up to 1 200 V d.c. or up to 1 000 V a.c. with rated frequencies up to 30 kHz and for use up to 2 000 m above sea level.

The minimum clearances indicated in this report do not apply where ionized gases (e.g. flames or arcs) occur. Special requirements for such situations may be specified at the discretion of the relevant Technical Committee.

This report does not deal explicitly with distances through solid or liquid insulation, with gases other than air or with compressed gases. However, it is recommended that any solid insulation be so dimensioned that a clearance will flash over at a value of voltage so low that no damage will be done to the solid insulation.

Notes 1. -The rated voltages 1 000 V a.c. and 1 200 V d.c. are traditional IEC limits for low-voltage equipment and only represent the formal limitation of the scope. Higher voltages may exist in circuits internal to the equipment.^*

2. -The altitude of 2 000 in above sea level is tlie traditional highest altitude for low-voltage cquipment covered by IEC standards. Requircincnts for altitudes exceeding 2 000 m can be derived from Appendix A.

^* Attention is however drawn to the fact that Technical Committee No. 64, Sub-committee 17R and Sub-Committee 17D consider 1 500 V d.c. as the upper limit of the low-voltage range.