pertinent data and corrective actions taken, will be prepared, to assure the
adequacy of flooring and work surfaces. This record will be kept on file
locally for at least 2 years and then destroyed.
(b) For the purpose of this paragraph, the term nonconductive is
used to define the ability of a material to withstand a voltage potential
with little or no current flow through the material to be tested. A high
resistance measurement instrument (ZM-21/U Megger, or equivalent) with a
minimum output of 500 volts shall be used. One electrode of the measurement
instrument should be firmly connected to the facility certified ground. The
other electrode should be connected to a 5 pound metal block, which has a
contact surface of 5 square inches of good conducting material. The block
should be equipped with a nonconductive strap to pull it along the surface
under test.
The entire surface of the nonconductive floorings or work
surfaces shall be tested to determine the points of lowest resistance to
assure compliance with these requirements.
(7) Bench tops in electrical/electronic repair shops should be
nonconductive, and only a minimum of connected equipment should be on the
bench tops.
Figure 3.
Testing insulating floors
80
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