Keysight U1241B and U1242B User’s and Service Guide 3
Safety Symbols
The following symbols on the instrument and in the documentation indicate 
precautions which must be taken to maintain safe operation of the instrument.
Direct current (DC) Caution, risk of electric shock
Alternating current (AC)
Caution, risk of danger (refer to this manual for 
specific Warning or Caution information)
Both direct and alternating current
CAT III 
1000 V
Category III 1000 V Overvoltage Protection
Earth (ground) terminal
CAT IV 
600 V
Category IV 600 V Overvoltage Protection
Equipment protected throughout by double 
insulation or reinforced insulation