User Manual
GMC-I Messtechnik GmbH 31
8.6 Insulation Resistance Measurement – RISO
R
ISO
Single measurements, rotary switch level: green
Switch
Position
Measuring Functions Measurement 
Type,
Without Mains
to Test Socket
R
ISO
R
ISO
Insulation resistance (PC I/PC II) LN(TS) - PE(TS)
LN(TS) - P1
P1 - P2 
1
PE(mains) - P1
PE(TS) - P1
LN(TS) - P1//PE(TS)
U
ISO
Test  voltage
1
Connection for 2
nd
 test probe for 2-pole measurement with SECUTEST 
PRO only (or instrument with feature
 H01)
Application, Definition, Measuring Method
Protection Class I Devices 
– M
easurement type LN(TS) - PE(TS) 
– DUT mains plug to test socket 
Schematic Diagram 
Insulation resistance is measured between short-circuited mains 
terminals (L-N) and protective conductor PE.
Wiring Diagram  
Protection Class II Devices 
with Exposed Conductive Parts 
– M
easurement type LN(TS) - P1 
– DUT mains plug to test socket 
– Test probe P1 to P1 terminals
Schematic Diagram 
Insulation resistance is measured between short-circuited mains 
terminals (L-N) and external conductive parts which can be con-
tacted with test probe P1 and are not connec
ted to the housing.
Wiring Diagram  
Protection Class II Devices with Outputs for Safety Extra-Low Voltage 
– 
Measurement type LN(TS) - P1 
– DUT mains plug to test socket 
– Test probe P1 to P1 terminals
Schematic Diagram  
Insulation resistance is measured between short-circuited mains 
terminals (L-N) and the short-circuited safety extra-low voltage 
outputs which are contacted with probe P1.
Wiring Diagram  










