Hioki 3285-20, Instruction Manual, Page: 11 / 85

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Safety Information
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CAT II
Primary electrical circuits in equipment
connected to an AC electrical outlet by a
power cord (portable tools, household
appliances, etc.)
CAT II covers directly measuring
electrical outlet receptacles.
CAT III Primary electrical circuits of heavy
equipment (fixed installations) connected
directly to the distribution panel, and
feeders from the distribution panel to
outlets.
CAT IV The circuit from the service drop to the
service entrance, and to the power meter
and primary overcurrent protection device
(distribution panel).
Measurement categories
This instrument complies with CAT III safety
requirements.
To ensure safe operation of measurement
instruments, IEC 61010 establishes safety standards
for various electrical environments, categorized as
CAT II to CAT IV, and called measurement
categories. These are defined as follows.
Using a measurement instrument in an environment
designated with a higher-numbered category than
that for which the instrument is rated could result in
a severe accident, and must be carefully avoided.
Use of a measurement instrument that is not CAT-
rated in CAT II to CAT IV measurement
applications could result in a severe accident, and
must be carefully avoided.