User Manual
GMC-I Messtechnik GmbH 47
Special Conditions for Insulation Resistance Measurement
Attention!
!
Insulation resistance can only be measured at voltage-
free objects.
If measured insulation resistance is less than the selected limit 
value, the U
L
/R
L
 LED lights up.
If an interference voltage of 
≥ 25 V is present within the system, 
insulation resistance is not measured. The MAINS/NETZ LED 
lights up and the “interference voltage” pop-up message appears.
All conductors (L1, L2, L3 and N) must be tested against PE!
Attention!
!
Do not touch the instrument’s terminal contacts during 
insulation resistance measurements!
If nothing has been connected to the terminal contacts, or if a 
resistive load component has been connected for measurement, 
your body would be exposed to a current of approx. 1 mA at a 
voltage of 1000 V. 
The noticeable shock may lead to injury (e.g. resulting from a star-
tled reaction etc.).
Discharging the Device Under Test
Attention!
!
If measurement is performed at a capacitive object such 
as a long cable, it becomes charged with up to approx. 
1000 V! 
Touching such objects is life endangering!
When an insulation resistance measurement has been performed 
on a capacitive object it is automatically discharged by the instru-
ment after measurement has been completed. Contact to the 
device under test must be maintained to this end. The falling volt-
age value can be observed at the U display.
Do not disconnect the DUT until less than 10 V is displayed for U!
Evaluation of Measured Values
Instrument measuring error must be taken into consideration in 
order to assure that the limit values set forth in DIN VDE regula-
tions are not fallen short of. The required minimum display values 
for insulation resistance can be determined with the help of Table 
3 on page 92. These values take maximum device error into con-
sideration (under nominal conditions of use). Intermediate values 
can be interpolated.
11.2 Special Case: Earth Leakage Resistance (R
EISO
)
This measurement is performed in order to determine electro-
static discharge capacity for floor coverings in accordance with 
EN 1081.
Select Measuring Function
Set Parameters
* Freely adjustable voltage (see section 5.7)
Connection and Test 
Set-Up 
➭ Rub the floor covering at the point at which measurement is to 
be performed with a dry cloth.
➭ Place the 1081 floor probe onto the point of measurement 
and load it with a weight of at least 300 N (30 kg).
➭ Establish a conductive connection between the measuring 
electrode and the Test Probe and connect the measuring 
adapter (2-pole) to an earth contact, e.g. the earthing contact 
at a mains outlet or a central heating radiator (prerequisite: re-
liable ground connection).
Start Measurement
The limit value for earth leakage resistance from the relevant regu-
lations applies.
R
ISO 
R
INS
Limit value:
RE(ISO) > limit value
U
L
 ⏐ R
L
R
EISO
Voltage type: constant
Test voltage : 15 V/50 V/100 V/250 V/325 V/500 V/1000 V*
Voltage type: rising/ramp
Earth leakage 
resistance:










