National Instruments NI 9403E - Manual (Page 14)

NI 9403E Operating Instructions and Specifications 14 ni.com
Measurement Category I is for measurements performed on
circuits not directly connected to the electrical distribution system
referred to as MAINS voltage. MAINS is a hazardous live electrical
supply system that powers equipment. This category is for
measurements of voltages from specially protected secondary
circuits. Such voltage measurements include signal levels, special
equipment, limited-energy parts of equipment, circuits powered by
regulated low-voltage sources, and electronics.
Caution Do not connect the NI 9403E to signals or use
for measurements within Measurement Categories II,
III, or IV.
Safety Standards
This product meets the requirements of the following standards of
safety for electrical equipment for measurement, control, and
laboratory use when installed in a suitable enclosure:
• IEC 61010-1, EN 61010-1
• UL 61010-1, CSA 61010-1
Note For UL and other safety certifications, refer to the
product label or the Online Product Certification section.