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Measurement categories (Overvoltage categories)
This instrument complies with CAT III (1000 V) and CAT
IV (600 V) safety requirements.
To ensure safe operation of measurement instruments
IEC 61010 establishes safety standards for various elec-
trical environments, categorized as CAT I to CAT IV, and
called measurement categories. These are defined as fol-
lows.
Higher-numbered categories correspond to electrical
environments with greater momentary energy. So a mea-
surement device designed for CAT III environments can
endure greater momentary energy than a device
designed for CAT II.
Using a measurement instrument in an environment des-
ignated with a higher-numbered category than that for
which the instrument is rated could result in a severe
accident, and must be carefully avoided.
Never use a CAT I measuring instrument in CAT II, III, or
IV environments.
The measurement categories comply with the Overvolt-
age Categories of the IEC60664 Standards.
CAT I Secondary electrical circuits connected to an
AC electrical outlet through a transformer or
similar device.
CAT II Primary electrical circuits in equipment con-
nected to an AC electrical outlet by a power
cord (portable tools, household appliances,
etc.)
CAT III Primary electrical circuits of heavy equip-
ment (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 ser-
vice entrance, and to the power meter and
primary overcurrent protection device (distri-
bution panel).
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