Measurement Category I is for measurement 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 included signal levels,
special equipment, limited-energy parts of equipment, circuits
powered by regulated low-voltage sources, and electronics.
Caution Do not connect to signals or use for
measurements within Measurement Categories II, III,
or IV.
Isolation Voltages
Port-to-earth ground
Continuous 60 VDC, Measurement
Category I up to 5,000 m in
altitude
18 | ni.com | NI 9871 Getting Started Guide