20 Mechanical strength
20.1 Tools shall have adequate mechanical strength, and shall be so constructed that they withstand
such rough handling as may be expected in normal use.
Compliance is checked by the tests specified in 20.2, 20.3 and 20.4.
Following the tests, the tool shall withstand an electric strength test as specified in clause 15, and shall
show no damage which could impair compliance with this standard; in particular, live parts shall not have
become accessible, as specified in clause 9.
Damage to the finish, small dents which do not reduce creepage distances or clearances below the values
specified in 28.1, or small chips which do not adversely affect protection against shock or moisture are
neglected.
The function of mechanical safety devices shall not be impaired thereby.
Cracks not visible to the naked eye and surface cracks in fibre-reinforced mouldings and the like are
ignored.
If a decorative cover is backed by an inner cover, a fracture of the decorative cover is neglected when the
inner cover withstands the test after removal of the decorative cover.
20.2 Blows are applied to the tool by means of the spring-operated impact test apparatus according to
clause 5 of IEC 60068-2-75.
The spring is so adjusted that it causes the hammer to strike with an impact energy as shown in Table 4.
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