Amprobe AM-270 Industrial-Multimeter - Manual (Page 8)

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Measurement Category IV (CAT IV) is for 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.
Measurement Category III (CAT III) is for 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, for example, stationary motors with permanent
connection to the fixed installation.
Measurement Category II (CAT II) is for measurements performed on circuits
directly connected to the low voltage installation. Examples are measurements
on household appliances, portable tools and similar equipment.
� WARNING
To reduce the risk of fire or electric shock, do not expose this product to
rain or moisture. To avoid electrical shock hazard, observe the proper
safety precautions when working with voltages above 60 VDC or 30 VAC
rms. These voltage levels pose a potential shock hazard to the user. Do
not touch test lead tips or the circuit being tested while power is applied
to the circuit being measured. Keep your fingers behind the finger guards
of the test leads during measurement. Inspect test leads, connectors,
and probes for damaged insulation or exposed metal before using the
instrument. If any defects are found, replace them immediately. Do not
measure any current that exceeds the current rating of the protection
fuse. Do not attempt a current measurement to any circuit where
the open circuit voltage is above the protection fuse voltage rating.
Suspected open circuit voltage should be checked with voltage functions.
Never attempt a voltage measurement with the test lead inserted into
the µA/mA or A input jack. Only replace the blown fuse with the proper
rating as specified in this manual. Only use the accompanied test leads, or
replace with the same rating or better.
� CAUTION
Disconnect the test leads from the test points before changing functions.
Always set the instrument to the highest range and work downward for
an unknown value when using manual ranging mode.