Iec Measurement Category Definitions; Non Category; Measurement Category Ii (Cat Ii); Measurement Category Iii (Cat Iii) - Keysight N2804 User Manual

IEC Measurement Category Definitions

Definitions and Examples (Clause 6.5.2).

Non Category

Mains isolated is for measurements performed on circuits not directly connected
to a mains supply. For example, measurements in circuits not derived from a mains
supply and specially protected (internal) circuits derived from a mains supply. In
the latter case, transient stresses are variable. For that reason, it is required that
the transient withstand capability of the equipment is made known to the user.

Measurement Category II (CAT II)

Measurement category II is for measurements performed on circuits directly
connected to the low voltage installation. For example, household appliances,
portable tools, and similar equipment.

Measurement Category III (CAT III)

Measurement category III is for measurements performed in the building
installation. For example, measurements on distribution boards, circuit breakers,
wiring including cables, bus-bars, junction boxes, switches, socket-outlets in the
fixed installation and equipment for industrial use like, for example, stationary
motors with permanent connections to the fixed installation.

Measurement Category IV (CAT IV)

Measurement category IV is for measurements performed at the source of the
low-voltage installation. For example, electricity meters and measurements on
primary over-current protection devices and ripple control units.
N2804/5A Differential Probes User's Guide
IEC Measurement Category Definitions
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