© PCE Instruments
3
1.2
Safety categories
Category
Short description
Typical applications
CAT II
One-phase measurements, e. g.
of sockets or cables
Household appliances, electric power tools,
measuring points 10 m away from a CAT III
source, measuring points 20 m away from a
CAT IV source
CAT III
Three-phase measurements or
one-phase measurements, e. g.
of light circuits in commercial
buildings
Motors, switches, sub-distributors in a three-
phase circuit, light circuits in commercial
buildings, supply cables for industrial plants,
electrical appliances or connections near a
CAT III source
The measuring category (CAT) arise from the combination of the meter, the test leads and the
accessories. To know what CAT to work with, you must find out what component has the lowest
CAT and use this CAT.
Important:
When you have removed the insulation from the test leads, these will correspond to
CAT II.
Fig. 1: Insulated tip
Fig. 2: Uninsulated tip
