6
Safety Information
Measurement categories
To ensure safe operation of measuring instruments, IEC 61010 establishes safety standards
for various electrical environments, categorized as CAT II to CAT IV, and called measurement
categories.
DANGER
• Using a measuring 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.
• Never use a measuring instrument that lacks category labeling in a CAT II to CAT
IV measurement environment. Doing so could result in a serious accident.
The instrument conforms to the safety requirements for CAT III 1000 V, CAT IV 600 V measuring
instruments.
CAT II: When directly measuring the electrical outlet receptacles of the primary electrical circuits
in equipment connected to an AC electrical outlet by a power cord (portable tools,
household appliances, etc.).
CAT III: When measuring the primary electrical circuits of heavy equipment (xed installations)
connected directly to the distribution panel, and feeders from the distribution panel to
outlets.
CAT IV: When measuring the circuit from the service drop to the service entrance, and to the
power meter and primary overcurrent protection device (distribution panel).
T
Outlet
CAT II
Internal Wiring
Distribution Panel
Service Entrance
Service Drop
CAT IV
Power Meter
CAT III
Fixed Installation
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