Table L.1 – Minimum creepage distances and clearances between parts of opposite polarity
millimetres
≤
15V
>15V and
≤
32V
>32V
Creepage
Distance
Clearance
Creepage distance
Clearance
Creepage distance
Clearance
–
0,8
–
1,5
2,0
1,5
Distances through slots or openings in external parts of insulating material are measured to metal foil in
contact with the accessible surface; the foil is pushed into corners and the like by means of the standard
test finger of Figure 1, but is not pressed into openings.
The sum total of distances measured between parts operating at hazardous voltage and accessible
surfaces is determined by measuring the distance from each part to the accessible surface. The distances
are to be added together to determine the sum total. See Figure L.1. For the purpose of this determination,
one of the distances shall be 1,0 mm or greater. See annex A, cases 1 to 10.
If necessary, a force is applied to any point on bare conductors and to the outside of metal enclosures,
in an endeavour to reduce the creepage distances and clearances while taking the measurements.
The force is applied by means of a test finger having a tip as shown in Figure 1 and has a value of:
– 2 N for bare conductors;
– 30 N for enclosures.
If a barrier is interposed, and if it is in two parts which are not cemented together, the creepage distance
is also measured through the joint.
If a barrier is interposed, clearances are measured over the barrier or, if the barrier is in two parts with
mating surfaces which are not cemented together, through the joint.
When assessing creepage distances and clearances, the effect of insulating lining of metal enclosures or
covers is taken into consideration.
Means provided for fixing the tool to a support are considered to be accessible.
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