U1241B/U1242B User’s and Service Guide III
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) Off (supply)
Alternating current (AC) On (supply)
Both direct and alternating current Caution, risk of electric shock.
Three-phase alternating current Caution, risk of danger (refer to this
manual for specific Warning or
Caution information).
Earth (ground) terminal Caution, hot surface.
Protective conductor terminal Out position of a bi-stable push 
control.
Frame or chassis terminal In position of a bi-stable push 
control.
Equipotentiality
CAT III
1000 V
Category III 1000 V Overvoltage 
Protection
Equipment protected throughout by 
double insulation or reinforced 
insulation.
CAT IV
600 V
Category IV 600 V Overvoltage 
Protection