Note that references are to IEC 60950 Third Edition 1999-04. Where the references in the Second Edition differ, they appear in parentheses.
IEC 60950 limits the size of openings in the top
and sides
of a product's enclosure in order to prevent access to electrical or mechanical hazards as well as to prevent objects falling into the product. Openings in the sides and the bottom of a product's enclosure must be sized so as to
minimize the possibility of flame, molten metal, flaming or glowing particles of flaming drops being emitted from the product and causing a fire hazard to the product's
surroundings.
CONSTRUCTIONAL REQUIREMENTS - TOPOpenings in the top of a fire enclosure, electrical enclosure or openings directly above bare parts at hazardous voltages:
- must not exceed 5 mm in any dimension
- or must not exceed 1 mm width, regardless of length,
- or must be constructed (e.g. with traps or restrictions) so that falling objects cannot reach parts at
hazardous voltage.
CONSTRUCTIONAL REQUIREMENTS - SIDESOpenings in the side of a fire enclosure or
electrical enclosure:
- must not exceed 5 mm in any dimension
- or must not exceed 1 mm width, regardless of length,
- or must have louvres which deflect outwards falling objects.
- must be constructed so that falling objects are unlikely to reach parts at
hazardous voltage.
Complete requirements are given in IEC 60950, clause 4.6 (4.3.14 and 4.3.15).
CONSTRUCTIONAL REQUIREMENTS- SIDES and BOTTOM OF FIRE ENCLOSUREIf, as a result of faults, there is a possibility that flame, molten metal, flaming or glowing particles of flaming drops
can be emitted from the product and cause a fire hazard to the product's surroundings, there are limitations in the size of openings on the bottom and sides of the enclosure. The
requirements are dependent on several variables, including the materials of components in the enclosure, the enclosure material and aspects of the nature of the product.
Requirements for specific cases are found in clause 4.4.6 of the standard.
REFERENCES
Complete requirements are given in IEC 60950, clause 4.6 (4.3.14, 4.3.15 and 4.4.6)
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