| The electrical tests. |
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Page 4 of 5
8.5.2 - Tests of non-conducting floors and wallsWhere protection against indirect contact is provided by a non-conducting location, the following requirements apply. 1. - there must be no protective conductors 2. - if socket outlets are used they must not have an earthing contact 3. - it should be impossible for any person to touch two exposed conductive parts at the same time 4. - floors and walls must be insulating. To test this last item and so to make sure that the floors and walls are non-conducting, their insulation has to be tested. The requirements are shown in {Fig 8.12}, the electrodes used for making contact
Fig 8.12 - Insulation test of floors and walls for non-conducting location
with floors and walls being a special type which are pressed
onto the surface with a force of not less than 750 N (77 kg or 169 lb) for
floors or 250 N (26 kg or 56 lb) for walls. The resulting insulation resistance
of not less than three points on each surface, one of which must be between 1 m
and 1.2 m from an extraneous conductive part (if there is one), measured at 500
V, must not be less than 0.5 MOhms. Attention is drawn to the natural reduction
in the insulation resistance of a surface as humidity increases. Where
insulation is applied to an extraneous conductive part to provide a
non-conducting location, this insulation must be tested with an alternating p.d.
of 2 kV. In normal use, the leakage current should not exceed I mA. |
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