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Keysight M9180 Series Startup Guide
IEC Measurement Category II overvoltage protection
To protect against the danger of electric shock, the Keysight M9180 Series digital
multimeters (DMMs) provide overvoltage protection for line-voltage mains
connections meeting both of the following conditions:
The HI and LO input terminals are connected to the mains under Measurement
Category II conditions, defined below,
and
The mains are limited to a maximum line voltage of 300 VAC (240 VAC for the
M9181A).
IEC Measurement Category II includes electrical devices connected to mains at an
outlet on a branch circuit. Such devices include most small appliances, test
equipment, and other devices that plug into a branch outlet or socket. The M9180
Series DMMs may be used to make measurements with the HI and LO inputs
connected to mains in such devices, or to the branch outlet itself (up to 300 VAC,
or 240 VAC for the M9181A). However, the DMMs may not be used with their HI
and LO inputs connected to mains in permanently installed electrical devices such
as the main circuit-breaker panel, sub-panel disconnect boxes, or permanently
wired motors. Such devices and circuits are subject to overvoltages that may
exceed the protection limits of the M9180 Series.
WARNING
– During and after installing your DMM, verify that no loose wires or ribbon
cables infringe upon any of the internal circuits of the DMM, as this may
apply measurement voltages to your chassis, causing electrocution and/
or damage to your chassis!
– To avoid shock hazard, install the DMM only into a chassis that has its
power connector connected to a power receptacle with an earth safety
ground.
– When making any measurements above 50 VDC or 40 VAC, only use
safety test leads, such as Keysight test leads.
NOTE
The M9182A and M9183 can measure voltages up to 330 VAC in circuits that are
isolated from mains (CAT I).
