Hioki 9196, Instruction Manual

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Overvoltage categories (CAT)
This product conforms to the safety requirements for CAT II mea-
surement products.
To ensure safe operation of measurement products, IEC 60664
establishes safety standards for various electrical environments,
categorized as CAT I to CAT IV, and called overvoltage categories.
These are defined as follows.
Higher-numbered categories correspond to electrical environments
with greater momentary energy, so a measurement product
designed for CAT III environments can endure greater momentary
energy than one designed for CAT II. Using a measurement prod-
uct in an environment designated with a higher-numbered category
than that for which the product is rated could result in a severe
accident, and must be carefully avoided.
CAT I Secondary electrical circuits connected to an AC electrical
outlet through a transformer or similar device.
CAT II Primary electrical circuits in equipment connected to an AC
electrical outlet by a power cord (portable tools, household
appliances, etc.)
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).