6
Keysight U1241B and U1242B User’s and Service Guide
Measurement Category
The U1241B and U1242B have a safety rating of CAT III, 1000 V; and CAT IV, 600 V.
O
Other circuits that are not directly connected to the mains.
Measurement CAT II
Measurements performed on circuits directly connected
to a low-voltage installation. Examples are measurements on household
appliances, portable tools, and similar equipment.
Measurement CAT III
Measurements performed in the building installation.
Examples are 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, and some other equipment
including stationary motors with permanent connection to the fixed installation.
Measurement CAT IV
Measurements performed at the source of the
low-voltage installation. Examples are electricity meters and measurements on
primary overcurrent protection devices and ripple control units.