Metrix MX 535 User manual

Installation tester
GB - User’s manual
MX 535

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WARNING, risk of DANGER! The operator must refer to these instructions whenever this danger symbol appears.
WARNING, risk of electric shock. The voltage applied to parts marked with this symbol may be hazardous.
Useful information or tip. Earth.
The voltage on the terminals must not exceed 550 V. Instrument protected by reinforced insulation.
The product is declared recyclable following a life cycle analysis in accordance with standard ISO 14040.
Chauvin Arnoux has adopted an Eco-Design approach in order to design this appliance. Analysis of the complete
󰀨-
ance exceeds regulation requirements with respect to recycling and reuse.
The CE marking indicates conformity with European LVD and EMC directives.
The rubbish bin with a line through it means that in the European Union, the product must undergo selective disposal
in compliance with Directive WEEE 2012/19/EU.

Measurement category IV corresponds to measurements taken at the source of low-voltage installations.
Example: power feeders, counters and protection devices.
Measurement category III corresponds to measurements on building installations.

Measurement category II corresponds to measurements taken on circuits directly connected to low-voltage installations.
Example: power supply to electro-domestic devices and portable tools.
PRECAUTIONS FOR USE
This instrument is compliant with safety standard IEC 61010-2-034, the leads are compliant with IEC 61010-031, and the current
sensors are compliant with IEC 61010-2-032, for voltages up to 600V in category III.
Do not use the instrument for measurements on circuits that are not in measurement categories II, III, or IV or that might be con-
nected inadvertently to circuits that are not in measurement categories II, III, or IV.
The operator and/or the responsible authority must carefully read and clearly understand the various precautions to be taken
in use. Sound knowledge and a keen awareness of electrical hazards are essential when using this instrument.

Do not use the instrument on networks of which the voltage or category exceeds those mentioned.
Do not use the instrument if it seems to be damaged, incomplete, or poorly closed.
Before each use, check the condition of the insulation on the leads, housing, and accessories. Any item of which the insulation
is deteriorated (even partially) must be set aside for repair or scrapping.
Before using your instrument, check that it is perfectly dry. If it is wet, it must be thoroughly dried before it can be connected or
used.
Use only the leads and accessories supplied. The use of leads (or accessories) of a lower voltage or category limits the voltage
or category of the combined instrument and leads (or accessories) to that of the leads (or accessories).
Use personal protection equipment systematically.

All troubleshooting and metrological checks must be performed by competent and accredited personnel.
Thank you for purchasing a MX 535 installation tester.
To obtain the best service from your instrument:
read this user manual carefully,
 with the precautions for use.
> 550 V

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CONTENTS
1. FIRST START-UP.................................................................................................................................................................4
1.1. Unpacking....................................................................................................................................................................4
1.2. Accessories .................................................................................................................................................................4
1.3. Inserting the rechargeable batteries ............................................................................................................................5
1.4. Using primary batteries................................................................................................................................................6
1.5. Charging the battery ....................................................................................................................................................6
1.6. Carrying the device......................................................................................................................................................7
1.7. Use on a desktop.........................................................................................................................................................7
2. PRESENTATION OF THE DEVICE ....................................................................................................................................8
2.1. MX 535 ........................................................................................................................................................................8
2.2. Functions of the instrument .........................................................................................................................................9
2.3. Keys.............................................................................................................................................................................9
2.4. Display unit ................................................................................................................................................................10
3. USE...................................................................................................................................................................................... 11
3.1. Voltage measurement................................................................................................................................................ 11
3.2. Resistance and continuity measurement...................................................................................................................13
3.3. Insulation resistance measurement...........................................................................................................................15
3.4. 3P earth resistance measurement.............................................................................................................................17
3.5. Loop impedance measurement ................................................................................................................................20
3.6. Test of residual current device...................................................................................................................................23
3.7. Current measurement................................................................................................................................................27
3.8. Direction of phase rotation.........................................................................................................................................28
3.9. Auto RCD function .....................................................................................................................................................29
 .................................................................................................................................30
4. MEMORY FUNCTION ........................................................................................................................................................31
4.1. Organization of the memory ......................................................................................................................................31
4.2. Storing measurements ..............................................................................................................................................31
4.3. Reading the measurements ......................................................................................................................................31
4.4. Erasing measurements..............................................................................................................................................32
5. BLUETOOTH LINK ............................................................................................................................................................33
6. TECHNICAL CHARACTERISTICS ..................................................................................................................................34
6.1. General reference conditions ....................................................................................................................................34
6.2. Electrical characteristics ............................................................................................................................................34
6.3. Variations in the range of use ....................................................................................................................................40
6.4. Intrinsic uncertainty and operating uncertainty ..........................................................................................................42
6.5. Power supply .............................................................................................................................................................42
6.6. Environmental conditions ..........................................................................................................................................43
6.7. Mechanical characteristics ........................................................................................................................................44
6.8. Conformity to international standards........................................................................................................................44
6.9. Electromagnetic compatibility (CEM).........................................................................................................................44
7. MAINTENANCE..................................................................................................................................................................45
7.1. Cleaning ....................................................................................................................................................................45
7.2. Replacing the batteries..............................................................................................................................................45
7.3. Updating of the internal software...............................................................................................................................45
7.4. Calibrating the instrument..........................................................................................................................................46
8. WARRANTY........................................................................................................................................................................50

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1. FIRST START-UP
1.1. UNPACKING
1One MX 535.
26 rechargeable Ni-MH batteries.
3One shaver USB cable.
4One mains USB adapter (5V, 2A).
5One tripod cable with mains plug (of the type used in the country of sale).
6Three elbow-straight safety cables (red, black, and green).
7Three crocodile clips (red, black, and green).
8One black probe tip.
9
10 One multilingual quick start guide.
11 One multilingual safety data sheet.
12 One battery data sheet.
13 One test report with record of measurements.
14 One carrying bag.
15 One 4-point hands-free strap.
1.2. ACCESSORIES
No. 4 remote control probe
MN73A 2A/200A current clamp
For the accessories and spares, consult our web site:
www.chauvin-arnoux.com
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
















         







190,rue Championnet
75876PARISCedex 18
FRANCE
ATTESTATION DE VERIFICATION
CHECKING ATTESTATION
Numéro de l'appareil :
Equipment number
Établien usine, ce document atteste que le produit ci-dessus a été vérifié et est conforme aux
conditionsd'acceptation définies dans nos procédures de fabrication et de contrôle.
Tousles moyensde mesure et d'essai utilisés pour vérifier cet appareil sont raccordés aux
étalonsnationaux et internationaux soit par l'intermédiaire d'un de nos laboratoires de métrologie
accréditésCOFRAC soit par un autre laboratoire accrédité.
Aprèssa mise en service, cet instrument doit être vérifié à intervalle régulier
auprèsd'un service de métrologie agréé.
Pourtout renseignement veuillez contacter notre service après vente et d'étalonnage.
Atthe time of manufacture, this document certifies that the above product have been verified and
complieswith acceptance conditions defined in our manufacturing and testing procedures.
Everytest or measuring equipment used to verify this instrument are related to national
andinternational standards through one of our laboratories of metrology certified by french COFRAC
equivalentto NAMAS in the UK or through another certified laboratory.
Afterbeing in use, this instrument must be recalibrated within regular intervals
byan approved metrology laboratory.Please contact our after sales and calibration department:
Serviceaprès vente et d'étalonnageTEL:[phone] FAX:[phone]
Aftersales and calibration departmente-mail:[e-mail]
WEB: www.manumesure.com
www.chauvin-arnoux.com
Vérifiépar :
Testedby
ATTESTATIONDE CONFORMITE
COMPLIANCE ATTESTATION
Nous certifions que ce produit a été fabriqué conformément aux spécifications
techniques de constuction applicables.
We certify that this product is manufactured in accordance with applicable
constructing specifications.
907009 119 - 02/03
Type/
Model
:
Désignation de l'instrument :
Instrument designation
Signature :
Signature
➀
➅
➄
➃
➁➂
➆
➇
➈
➉
11 12
15
14
13
PE
TEST
FR - Guide de démarrage rapide
GB- Quick Start Guide
DE- Schnellstart-Anleitung
IT -Guida di Utilizzo rapido
ES - Guía de inicio rápido
MX 535
Contrôleurs d’installation
Installation testers
Installationstester
Controllori d’installazione
Controladores de instalación

5
1.3. INSERTING THE RECHARGEABLE BATTERIES

lever up.
Remove the battery compartment cover, then raise the rubber plug.

6
Insert the 6 rechargeable batteries, with the polarities as indicated.
Put the rubber plug back in place. Push it in correctly.
Put the battery compartment cover back in place; make sure that it is completely and correctly closed.
1.4. USING PRIMARY BATTERIES
If you prefer to use primary batteries in your instrument, you must parameterize your instrument so that it indicates the correct
charge level. The primary batteries deliver a higher voltage than the rechargeable batteries.
Insert batteries (primary or rechargeable) in your instrument as indicated above.
The instrument is switched on and the display unit indicates the progress of the charging.
> 100 VAC
< 240 VAC
50 / 60 Hz
2 A


> 2s
Press the 󰀨

The instrument displays bAtt
Or bAtt rECH
1.5. CHARGING THE BATTERY

Do not charge if there are primary batteries in the instrument.
Connect one end of the shaver USB cable (provided) to the terminal block of the MX535 and the other end to a wall outlet
using the mains-USB adapter (provided).

7
Charging takes approximately 6 hours.
Once charging is over, disconnect the plug. The instrument is ready to be used.
1.6. CARRYING THE DEVICE
The 4-point hands-free strap will let you use the device while leaving your hands free. Snap the four fasteners of the strap onto
the four lugs on the device.
Pass the strap around your neck.
Adjust the length of the strap,
Adjust the slope of the instrument.
1.7. USE ON A DESKTOP
Pull the props out, then fold them and put them in the other location.

8
2. PRESENTATION OF THE DEVICE
2.1. MX 535
PE
MX 535
INSTALLATION TESTER
Ω
MΩ
LOOP
RCD TEST
0
V / I
MEM
AUTO
MR
CLR
COM
AC
DC
I V L3
CHPS XE
L1NL2 PE
U
U
Uf Hz
HOLD
TEST
SITE
MR
Ik V/A NOISE RH !
UL250V 250V500V1000V
AC
I
∆ n
x1x.5
mA
R
M
Ω
MΩms<2Ω
kΩmA<1Ω
mV
LOOP
LOOP
RCD
M Ω
RCD
AUTO
AUX
123
E-3P
12
23
31
Ω
P
0
L3
L1
L2
+
+
L L
L3
L1 L2
5 V 2 A
600
V CAT III
Ω/MΩ
+
PS E XCH
LN PE COM
> 550 V
Terminal block.
One battery
charger input. 3 voltage inputs, one
of them for the remote
control probe.
-
tional) MN73A ammeter clamp.
Measurement validation
indicators.
Indicator of presence of volt-
age on PE.
󰀨 button.
Function keys.
Backlit LCD
display unit.
Other function
keys.
Navigation
keys.
TEST button.

9
2.2. FUNCTIONS OF THE INSTRUMENT
MX 535 installation tester is a portable measuring instruments with LCD display. It is powered by primary batteries or by recharge-
able batteries, which it can recharge.
This instrument is used to check the safety of electrical installations. It can be used to test a new installation before it is powered
up, to check an existing installation, whether in operation or not, or to diagnose a malfunction in an installation.
MX 535
Voltage measurement 
Continuity and resistance measurement 
Insulation resistance measurement 250V - 500V - 1000V
Earth resistance measurement (with 3 rods) 
Loop impedance measurement 
Test of type AC, A , F, B, B+ and EV residual current devices, in
ramp mode, in pulse mode, or in non-tripping mode 
Detection of direction of phase rotation 
Current measurement with an optional current clamp 
Storage of the measurements 
Bluetooth 
Self-test 
2.3. KEYS
 
P
Pressing the 󰀨 button switches the instrument on.
󰀨
If the 󰀨
mode.
TEST Pressing the TEST button starts insulation or loop measurements or RCD tests, and measurements in automatic
mode.
 
V / I Press the key once to make voltage measurements. If an ammeter clamp is connected, the instrument will make
current measurements.
Press again to determine the phase order.
3P Press the key once to make continuity measurements.
Press again to make resistance measurements.
A third press is used to make 3P earth measurements.
 Press the key once to enter the insulation measurement function.
LOOP Press the key once to enter the loop measurement function in no-trip mode.
Press again to enter the loop measurement function in trip mode.
RCD Press the key once to enter the RCD test function in no-trip mode.
Press again to enter the RCD test function in ramp mode.
Press a third time to enter the RCD test function in pulse mode.
AUTO Press the key once to enter the RCD test function in automatic mode.
Press again to enter the installation test function in automatic mode.

10
 
0
Press the key once to deactivate the audible signal emitted by the instrument.
Press again to reactivate it.
A sustained press serves to compensate the resistance of the leads.
P
Press the key once to switch on the backlighting.
󰀨
A long press on the key activates the Bluetooth link.
A second long press deactivates it.
MR
CLEAR
Press the key once to read the recorded measurements.
A long press erases all of the recorded data.
MEM Press the key once to record the last measurement made/displayed in the same site, in the next test number.
A long press records the last measurement made/displayed in another site, at test number 01.
 
to parameterize the measurements,
to browse while reading the memory.
2.4. DISPLAY UNIT
1Indicates the measurement in progress 6Parameters of the RCD function
2Indicates the connections 7Parameters of the AUTO function
3Indicates the state of the battery and the tempera-
ture of the instrument 8Display linked to the other function keys
4Main display 9Display linked to the recording function
5Secondary display
➅
➀➁➂
➆
➄
➃
➇➈
COM
AC
DC
I V L3
CHPS XE
L1NL2 PE
U
U
Uf Hz
HOLD
TEST
SITE
MR
Ik V/A NOISE RH !
UL250V 250V500V1000V
AC
I
∆ n
x1x.5
mA
R
M
Ω
MΩms<2Ω
kΩmA<1Ω
mV
LOOP
LOOP
RCD
M Ω
RCD
AUTO
AUX
123
E-3P
12
23
31
Ω
P
0
L3
L1
L2
+
+
L L
L3
L1 L2

11
3. USE
3.1. VOLTAGE MEASUREMENT
3.1.1. DESCRIPTION OF THE MEASUREMENT PRINCIPLE
The device separates the alternating voltage from the direct voltage and compares the amplitudes to decide whether the signal is
AC or DC. In the case of an AC signal, the frequency is measured and the instrument calculates and displays the RMS value of the
signal (AC + DC). In the case of a DC signal, the device does not measure its frequency, but calculates its mean value and displays it.
For measurements made at the mains voltage, the device checks that the connection is correct and displays the position of the

makes with their hands when holding the instrument, or with their stomach when the instrument is slung on the strap, or with the

3.1.2. MAKING A MEASUREMENT

Press the 󰀨 button to switch the instrument on.
The instrument starts up in voltage measurement mode (V).
V LN
Hz
TEST
SITE
V AC
DC
LN PE
Connect one end of the tripod cable to the measurement
terminals and the other end to the object to be measured.
The measurement is displayed. The instrument indicates
that it is making the measurement between the L and N
terminals. It is therefore possible to make the measurement
with two leads.
The instrument indicates whether the voltage is AC or DC.
If the voltage is AC, the instrument displays its frequency.
If the voltage is DC, the instrument also indicates its polarity.
V LN
TEST
SITE
V DC

12
3.1.3. CHECKING THE OPERATION OF THE INSTRUMENT
Before each use of the instrument, check its operation by making a voltage measurement on a known voltage. If the meas-
urement is incorrect, do not use the instrument.
3.1.4. ERROR INDICATION
If the measurement is outside the measurement range, in either voltage or frequency, the instrument so indicates.
If the voltage is less than 2V, the instrument cannot measure its frequency and displays - - -.
In the case of a live measurement (LOOP or RCD), the instrument shows where the phase should be on the outlet using the
symbol. If the phase is on the wrong side, the
L L
or
L L
symbol blinks to indicate that the tripod cable must be reversed.
L
Hz
TEST
SITE
V
PE
L
LOOP
AC
DC
LN PE

13

3.2. RESISTANCE AND CONTINUITY MEASUREMENT
3.2.1. DESCRIPTION OF THE MEASUREMENT PRINCIPLE
For continuity measurements, the instrument generates a 200mA direct current between the +and COM terminals. It then measures
the voltage present between these two terminals and from it deduces the value of R = V/I.
For resistance measurements, the device generates a DC voltage between the +and COM terminals. It then measures the current
between these two terminals and from it deduces the value of R = V/I.
3.2.2. MAKING A CONTINUITY MEASUREMENT
To comply with the IEC 61557 standard, continuity measurements must be made with a positive current, then with a negative cur-
rent. The 2 measurements must then be averaged. The reversal of the current serves to compensate for any residual electromotive
forces and, more important, to check that the continuity is in fact duplex.
When you make continuity measurements that are not contractual, you are not required to reverse the polarity or calculate the
average.
Turning the tripod connector around does not reverse the current.
Connect the leads between the +and COM terminals, short-circuit them, and compensate them by a sustained press on the
0
key until the display unit indicates StAb. You can then release the
0
key and the display unit indicates 0.00. The
󰀨

Ω3P
Press the  3P key to select the  function.

0
+COM
TEST
SITE
Ω
Ω
0COM +
+COM
R
TEST
SITE
A
Ω
Ω
0
<2Ω
COM +
Use the leads to connect the device to be tested to the +
and COM terminals of the instrument.
The object to be tested must not be live.
The measurement is displayed.
For as long as the measurement varies between some value and OL, the instrument remains on even if not in permanent mode.

14
3.2.3. VALIDATION OF THE MEASUREMENT
The instrument then indicates whether or not the measured value is OK:
 indicator lights and the instrument emits a continuous audible
signal.
 indicator lights.
.
If a spurious voltage appears during the measurement, the symbol is displayed, the instrument emits a continuous audible
signal, and the measurement is aborted.
3.2.4. MAKING A RESISTANCE MEASUREMENT

Ω3P
Press the  3P key a second time to select the function.
+COM
R
TEST
SITE
Ω
Ω
COM +
3.2.5. ERROR INDICATION
If the measurement is outside the measurement range, the instrument so indicates by displaying .
If a spurious voltage appears during the measurement, the symbol is displayed and the measurement is aborted.
3.2.6. REMOTE CONTROL PROBE
The optional no. 4 remote control probe is used to remote the +terminal.
When it is connected to the instrument, the symbol is displayed.
Use the leads to connect the device to be tested to the +
and COM terminals of the instrument.
The object to be tested must not be live.
The measurement is displayed.
For the use of the no. 4 remote control probe, refer to its user's
manual.
+COM
R

15
3.3. INSULATION RESISTANCE MEASUREMENT
3.3.1. DESCRIPTION OF THE MEASUREMENT PRINCIPLE
The device generates a DC test voltage between the +and . The value of this voltage depends on the resistance
to be measured: it is greater than or equal to UNwhen R ≥ RN= UN/1 mA, and less otherwise. The device measures the voltage
and current present between the two terminals and from them deduces the value of R = V / I.
The COM terminal is the voltage reference point and the +terminal delivers a positive voltage.
3.3.2. MAKING A MEASUREMENT

MΩ
Press the  key to select the  function.The instrument is set to voltage measurement.
Select the nominal test voltage UN
Select the alarm threshold of the NF C 61557 (NFC) or IEC 61557 (CEI) standard or no threshold (OFF) by a long press on

Thresholds for various standards and test voltages.
NF C CEI
250V  
500V  
1000V  
If the alarm is activated, it can serve to inform the user, by an audible signal, that the measurement exceeds the threshold,
with no need to look at the display unit.

TEST
TEST
SITE
COM +
M Ω
MΩ
+
500V
V
+COM
R
When you release the TEST button, the instrument displays dIS (discharge) to indicate that it is discharging the object tested. If
the object is not capacitive, discharging is very rapid. When the voltage falls below 25V, the dIS and symbols disappear from
the display unit.
Do not disconnect the instrument while the dIS symbol is still displayed.
The measurement remains frozen until you press the TEST button. The instrument then returns to voltage measurement.
Use the leads to connect the device to be tested to the
+and COM terminals of the instrument.
The object to be tested must not be live.
Press the TEST button and keep it pressed until the
measurement is stable. The symbol indicates that
the instrument is generating a hazardous voltage.

16
3.3.3. VALIDATION OF THE MEASUREMENT
If an alarm threshold is selected, the instrument informs you whether the measured value is OK or not:
If the measured value is greater than the threshold, the indicator lights and the instrument emits a continuous audible
signal.
If the measured value is below the threshold, the indicator lights.
3.3.4. ERROR INDICATION
If the measured value is outside the measurement range, the instrument so indicates.
If the object to be tested is live, the symbol is displayed; the TEST button cannot be pressed.
If a spurious voltage appears during the measurement, the symbol is displayed and the measurement is aborted.
3.3.5. REMOTE CONTROL PROBE
The optional no. 4 remote control probe makes it easier to trigger the measurement, thanks to its remoted TEST button. When it
is connected to the instrument, the symbol is displayed.
For the use of the no. 4 remote control probe, refer to its user's manual.
+COM
R

17
3.4. 3P EARTH RESISTANCE MEASUREMENT
This function is used to measure an earth resistance when the electrical installation to be tested is not live (new installation, for
example). It uses two auxiliary rods, with the third rod being constituted by the earth electrode to be tested (whence the name “3P”).
󰀨-
lation, the earthing strip of the installation must be open during the measurement.
3.4.1. DESCRIPTION OF THE MEASUREMENT PRINCIPLE
The device generates between the H and E terminals a square wave at a frequency of 128 Hz and an amplitude of 35 V. It meas-
ures the resulting current, IHE , along with the voltage present between the S and E terminals, USE. It then calculates the value of
RE= USE/IHE.
3.4.2. DESIGNATIONS OF THE TERMINALS
It is possible to change the names of the terminals in a 3P earth measurement from H S E to C P X. To do this, when you are in

3.4.3. MAKING A MEASUREMENT
There are several measurement methods. We recommend the «62%» method.
Connect the cables to the H and S terminals. Power down the installation and disconnect the earth strap. Then connect the E
terminal to the earth electrode to be checked.
Connect the leads between the H, Sand Eterminals, short-circuit them, and compensate the measurement leads by a sustained
press on the
0
key, until the display unit indicates StAb. You can then release the
0
key and the display unit indicates
󰀨

Ω3P
Press the  3P key three times to select the RE-3P function.
PS E XCH
62% d
d
HS
earth strap
TEST
SITE
Ω
0
HS E
RE-3P

0
PS E XCH
Choose the value of limit voltage UL: 25 or 50 V. Refer to § 3.5.2.
Plant the H and S rods in line with the earth electrode. The distance between the S rod and the earth electrode must be ap-
proximately 62% of the distance between the H rod and the earth electrode.
In order to avoid electromagnetic interference, we recommend paying out the full length of the cables, placing them as far apart
as possible, and not making loops.

18

TEST
TEST
SITE
Ω
HS E
RE-3P
0
Do not forget to reconnect the earth strap at the end of the measurement before powering the installation back up.
3.4.4. VALIDATION OF THE MEASUREMENT
To validate your measurement, move the S rod towards the H rod by 10% of d and make another measurement. Then move the
S rod, again by 10% of d, but towards the earth electrode.
Press the TEST button and keep it pressed until the measurement is stable.

HS
52% d
d
62% d
72% d
PS E XCH
The 3 measurement results must be the same to within a few percent. If this is the case, the measurement is valid. If not, it is

3.4.5. POSITIONING OF THE AUXILIARY RODS
To make sure that your earth measurements are not distorted by interference, we recommend repeating the measurement with the
󰀨
HS
E
H
S
d
2
d1
󰀨


19

either side of the line HE.
Avoid routing the connecting cables of the earth rods near or parallel to other cables (transmission or power supply), metal pipes,
rails, or fences, this in order to avoid the risk of cross-talk with the measurement current.
3.4.6. ERROR INDICATION
If there is a spurious voltage on the terminals, having an amplitude between 7V and UL(25 or 50V), the NOISE symbol is dis-
played and the TEST button cannot be pressed.
If there is a spurious voltage on the terminals, having an amplitude greater than UL(25 or 50V), it is hazardous; the symbol
is displayed and the TEST button cannot be pressed.
RH ! symbol blinks.
If a spurious voltage appears during the measurement, the NOISE symbol is displayed.
If a hazardous spurious voltage appears during the measurement, the symbol is displayed and the measurement is
aborted.
H
S
E
S

20
3.5. LOOP IMPEDANCE MEASUREMENT
In a TN or TT type installation, the loop impedance measurement is used to calculate the short-circuit current and to size the
protections of the installation (fuses or RCDs), especially their breaking capacity.
In a TT type installation, the loop impedance measurement makes it easy to determine the earth resistance without planting any
󰀨L-PE, is the loop impedance of the installation between
the L and PE conductors. It is barely greater than the earth resistance.
From this value and the conventional touch voltage limit (UL󰀨
of the RCD: I∆N< ULL-PE.
This measurement cannot be made in an IT type installation because of the high earthing impedance of the supply transformer,
which may even be completely isolated from earth.
3.5.1. DESCRIPTION OF THE MEASUREMENT PRINCIPLE
In no-trip mode, the instrument makes the measurement with a current of 12mA between the L and PE terminals. This low current
avoids tripping an RCD having a nominal current greater than or equal to 30mA.
In trip mode, the instrument makes the measurement with a current of 300mA between the L and PE terminals. This current will
trip an RCD having a nominal current is less than or equal to 300mA;
The instrument then calculates the short-circuit current Ik = ULPEL-PE.
The value of Ik serves to check the proper sizing of the protections of the installation (fuses or RCDs).
3.5.2. MAKING A NO-TRIP MEASUREMENT
Press the LOOP key to select the LOOP function.
L: 25 or 50V.
Connect the measuring cable to the device, then to the socket outlet of the installation to be tested.

Land PE terminals is correct in both amplitude and frequency.
If it is, the
L L
symbol lights steadily. Otherwise, the symbol blinks and it is not possible to make a loop measurement.
If there is a voltage on protection conductor PE, the instrument detects it and the
PE
indicator lights to warn the user. This
does not prevent starting the measurement.

LOOP
LN PE
TEST
SITE
Ω
LPE
LOOP
L
AIk
UL25 V
HOLD