6
Measurement Categories
The applicable measurement category is determined by the input mod-
ule being used.
To ensure safe operation of measurement instruments, IEC 61010
establishes safety standards for various electrical environments, catego-
rized as CAT II to CAT IV, and called measurement categories.
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 installa-
tions) 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).
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.
Do not touch high voltage lines with the
sensor or the instrument. They are not
insulated and the application of high volt-
age to this instrument may expose testing
personnel to high voltage that may at
worst lead to electric shock and death.
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