Megger LCB2500, LCB2000 User Manual

RCD & LOOP TESTERS
MEGGER LCB2000/2500

User Guide

MEGGER

®

Dear Customer,
Thank you for purchasing one of the new premium range

of Combinations products from AVO International. The
Combinations concept was created after listening to the
views of many users, and combine quality and versatile
features with the reliability and dependability you expect
from MEGGER products. Every instrument is designed
and manufactured to exacting standards and as such is
guaranteed for a full three years.

The MEGGER LCB2000 and LCB2500 are part of an
advanced range of combined loop and circuit breaker
testers designed to fully test RCDs and measure loop
impedance and prospective short circuit current, (PSCC),
on single and three phase systems rated up to 300V ac
r.m.s. to earth. Designed to comply with all relevant wiring
regulations, the units feature both standard and low
current loop test ranges guaranteed not to trip RCDs
rated at 30mA and above. Acomprehensive range of
RCD test facilities is provided to cater for the most
demanding situations whilst ingenius facilities such as
ramp and auto-sequence tests provide diagnostics for
troubleshooting nuisance tripping and reduce the time
taken for a series of tests considerably.

2

Results are clearly indicated on a large backlit liquid
crystal display. The LCB2500 also allows results to be
stored against specific circuit and distribution board
references. This instrument is directly compatible with

®

PowerSuite™for Windows™and NICEone

AVO
software and stored data may be quickly downloaded for

™

creation of professional installation test certificates.
Alternatively direct connection to a serial printer is
possible.

Contents

Safety Warning 4
Function Keys and Warning Symbols 5
Initial Setup 6
General Description 7
Wiring Diagram 9
Operation 10
Specifications 29
Accessories 33
Publications 34
Loop Resistance Tables 35
Repair and Warranty 36

Symbols used on the instrument are:

Caution: Refer to
accompanying notes

Maximum nominal system
voltage of 440V

Maximum 300V a.c.
CATIII to Earth

3

SAFETY WARNINGS

★ Safety Warnings and Precautions must be read and understood before the instru-

ment is used. They must be observed during use.

★ Continuity of protective conductors and earthed equipotential bonding of new or

modified installations must be verified before carrying out an earth fault loop
impedance test, or RCD test.

★ Circuit connections and exposed metalwork of an installation or equipment under

test must not be touched.

★ Do not move the rotary selector switch position while a test is in progress.
★ The LCD ‘neon’ voltage indicators cannot reveal a Neutral-Earth reversal.
★ The instrument should not be used if any part of it is damaged.
★ Test leads, probes and crocodile clips must be in good order, clean and with no

broken or cracked insulation.

NOTE

THE INSTRUMENTS MUST ONLY BE USED BY SUITABLY TRAINED AND COMPETENT PER-

4

Function Keys and Warning Symbols

KEYS:

ENTER SAVE

BACKLIGHT

RCD TEST TYPE DOWN

RCD TYPE UP

TEST EXIT

Note: On LCB2000 storage and download

functions are not available and are
not marked on the keys

Condition

System error

Low battery

Touch pad

>100V

Supply voltage
and frequency

out of range
Thermal trip

operated

Supply

interrupted

during test

Noise

Fuse ruptured

Memory full

Memory

corrupted

> or <

and limit

value

CauseDisplay Action

Hardware or
software fault.

Battery voltage
too low.

Earth voltage
too high.

Supply voltage or
frequency too high or
low for test.

Too rapid testing with no
pauses for heat
dissipation.

RCD tripped or
supply failure.

Excessive external
supply noise during
earth loop or RCD test.

Blown fuse.

Results memory full.

Results memory
unintelligible.

Switch ‘Off’, then ‘On’
and attempt re-test.

Replace battery.

Check installation or
wiring to the instrument.

—

Pause between tests
to allow cooling.

Confirm RCD rating and
check for excess earth
leakage current.

Identify and rectify, or
wait and re-test.

Return instrument
for repair.

Download results
and clear memory.

Press TEST to
attempt recovery.

5

Initial Setup

Instrument Setting
The instrument setting modifies the way the instrument

behaves, shown in the following table.

Setting A (Europe)
Line and Neutral Swap

allowed.
Auto Sequence RCD

does 5I test.
After RCD trip test,

contact voltage
displayed first.

1

⁄2I no trip RCD test not

2s
performed.

To change the setting:

1. Press and hold the Backlight key, then turn the
rotary selector switch from the OFF position to the
RCD 150mA 40ms position. The current setting will
be displayed.

2. To change the setting, toggle the I key until the
required setting is displayed.

3. To save the new setting, press the SAVE key. The
bleeper sounds and SET is displayed. To leave the
setting as it was, press the EXIT key.

6

Setting b (UK)
Line and neutral swap

not allowed.
Auto Sequence RCD

does 150mA test.
After RCD trip test,

trip time or current
displayed first.

1

⁄2I no trip RCD test

2s
performed.

Reset Factory Default Settings
The instrument will remember certain values such as

the VAR range RCD test current, even if the instrument
is switched off and the battery removed.

These can be reset to factory default settings as follows:

1. Press and hold the BACKLIGHT key, then turn the
rotary selector switch from the OFF position to the
RCD 150mA 40ms position. The current setting will
be displayed. Release the BACKLIGHT key.

2. Press the up and down keys together. The code clr
is displayed.

3. Confirm the operation by pressing the SAVE key, or
abort by pressing any other key. The current setting
will be displayed.

General Description

This instrument has been designed to fully test RCDs
and measure loop impedance and PSCC on single and
three phase systems with a rated voltage up to
300V a.c. r.m.s. to earth. It has been designed to
comply with U.K., European and other international
wiring regulations and standards.

Measured values are displayed on a large backlit digital
LCD. With the LCB2500 these values may also be stored
in internal memory for later recall to display, direct printing
to a standard serial printer, or downloaded to a PC for
storage, analysis and report generation.

Key Features
Storage of test results in memory (LCB2500 only)
Selectable backlight
Large clear liquid crystal display
Operates regardless of mains polarity
Automatic test start on voltage detection

Loop Tests
Direct indication of short circuit current
Phase-phase (up to 480V), phase-neutral and
phase-earth tests
No trip loop impedance tests with a resolution
down to 0.01Ω
No neutral needed for line to earth testing
(except for No Trip Loop L-PE 0.01Ω)

RCD tests
Tests selective (delayed), general and d.c. sensitive
RCDs

Contact voltage and loop resistance displayed
Selectable test current for programmable devices
Auto sequence test
Ramp test

General
Supply voltage and frequency measurement
Three Phase sequence indication
Mains outlet polarity indication

Application
The instrument may be be connected live to earth or

between live conductors of systems that have a rated
voltage of 300V a.c. rms to earth and an Installation
(Overvoltage) Category III or lower. This means that the
instrument may be connected to any fixed wiring of a
building installation, but not to primary supply circuits
such as overhead cables. To maintain user safety and
ensure accurate measurements, only use the test leads
supplied or recommended for use with this instrument.

The instrument is fuse protected to 440V 10kA. The
maximum current which could flow through this fuse in
the case of a fault is limited to 10 kA by the impedance
of the test leads.

When the low battery symbol appears, the cells are
nearly exhausted and should be replaced as soon as
possible. When the battery is exhausted, the instrument
will not perform tests and the cells must be replaced.
Use alkaline cells IEC LR6 (AA) or 1,5V nickel cadmium

7

cells only.
To install or replace the cells, disconnect the test leads,

switch the instrument off and loosen the captive screws
holding the battery compartment cover in place.
Remove the cover, lift out and disconnect the battery
holder to access the cells. Replace the cells, ensuring
that correct polarity is observed (shown on battery

Incorrect battery cell polarity

can cause electrolyte leakage resulting in

damage to the instrument

holder moulding).
Carefully re-connect the battery holder to the connector,

replace the battery holder in the compartment, and re­secure the cover. Remove the cells if the instrument is
not going to be used for any extended period of time.
Stored results are retained when the battery is
disconnected.

8

Test Leads
All test leads form part of the measuring circuit of the

instrument and must not be modified or changed in any
way, or be used with any other electrical instrument or
appliance. The power cord supplied with the Installation
Testers is a test lead that forms part of the measuring
circuit of the instrument. The overall length of this lead
must not be altered. If the power cord plug is not
suitable for your type of socket outlets, do not use an
adaptor. You may change the plug once only by cutting
the cord as close to the plug as possible and fitting a
suitable plug.

The colour code of the cord is:
Earth (Ground) Yellow/Green
Neutral Blue
Phase (Line) Brown

Note: A plug severed from the power cord must be

destroyed, as a plug with bare conductors is
hazardous in a live socket outlet.

Wiring Diagram

LOOP L-PE
LOOP L-N

Supply

Black

RCD

Red

Green

RCD

LOOP L-PE 0.1Ω (no trip)

LOOP L-PE 0.01Ω (no trip)

LOOP L-N

Black

Red

Black

Green

LOOP L-L

L1
L2
L3
N

P-E

Red

9

Operation

Backlight
The display backlight gives a clear display of

measurements in poor lighting conditions. The backlight
will briefly operate when the instrument is switched on.
To switch the backlight on, press the backlight key (see
key on page 4). Press the key again to switch the
backlight off.

To conserve battery power, the backlight will
automatically switch off after about 15 seconds (if the
battery voltage is low, this period is automatically
reduced).

Auto Shut-off
To extend battery life after a period of instrument

inactivity the instrument will switch itself off, preceded by
a series of bleeps. To switch the instrument back on,
press any key other than the TEST key.

Switched Probe SP2
This accessory can be used anywhere that the 2-wire

lead set is specified in this User Guide. The press switch
on the probe duplicates the function of the TEST key on
the instrument, allowing quick and easy testing.

Checking Earth Potential
To quickly distinguish live and earth, this feature provides

display indication if a voltage greater than 100V exists
between the earth connection and your finger.

1. In any switch position except OFF and RCL

10

(LCB2500 only), connect the earth connection (black
for the 2-wire lead set, green for the 3-wire lead set)
to earth.

2. Touch a finger to the metal pad on the top. This is
safe and will not endanger you.

3. If a voltage greater than 100V exists between the
finger (normally at earth potential) and the earth
wire, the warning symbol is displayed.

Voltage and Frequency Measurement
This instrument will display the supply voltage and

frequency in all switch positions except RCL and OFF.
The ENTER key will alternate between voltage and
frequency.

Power plug connection

1. Insert the power cord plug into an installation socket.

2. Supply voltage and polarity are displayed.

3. Press ENTER to alternate between supply voltage
and frequency.

3-Wire Lead Set Connection
If an installation socket is not available and it is
necessary to connect to all three conductors, use the 3­wire lead set.

1. On a single phase system connect the red lead to
phase, the black to neutral and the green to earth.

2. Supply voltage and polarity are displayed.

3. Press ENTER to alternate between supply voltage
and frequency.

Note: For connection to a three phase system, see

‘Determining Phase Sequence’.

When connected the instrument will display the Line to
Earth voltage except on the loop L-N switch position
when the line to neutral voltage is displayed or shown.

Polarity Indication
If connected to a single phase power supply by a plug

or by the 3-wire lead set, three LCD ‘neons’ marked L­PE, N-PE and L-N respectively will indicate supply
polarity. If a voltage is detected between their respective
two wires, the ‘neon(s)’ will activate. A ‘neon’ will usually
flash if one connection is open circuit.

Note: The presence of a voltage between phase and

earth does not prove earth continuity, as the earth
could have a high resistance and a voltage would
still be measured. To test earth continuity refer to
the sections on loop resistance or RCD testing.

If Setting A(see page 4) is set, the instrument will
automatically switch Line and Neutral as appropriate.
This enables a test to be performed without inverting the
plug connections. The live terminal of the wall socket is
identified by the addition of a separate symbol adjacent
to the ‘neons’.

Setting A (Europe)

L-PE N-PE L-N

Normal Supply (1)

Normal Supply (2)

Neutral Live

Neutral Open Circuit

Earth Open Circuit

Setting b (U.K.)

L-PE N-PE L-N

Normal Supply

L-N Reversed

Neutral Live

Neutral Open Circuit

Earth Open Circuit

11

Operation

Determining Phase Sequence
When connected to all conductors of a three phase

system, the instrument automatically displays the
sequence of phase rotation.

Connect the the Installation Testers as follows:­Line 1 Red phase Red lead

Line 2 Yellow phase Green lead
Line 3 Blue phase Black lead

If connected as above, the symbol is displayed
when the sequence is
1:2:3, or Red-Yellow-Blue. The symbol is displayed
when the sequence is 1:3:2,
or Red-Blue-Yellow. If one of the lines is faulty, neither
of the symbols is displayed and the normal ‘neon’
polarity indication is shown.

In the Loop L-N switch position the voltage between the
red and black leads is displayed. In other switch
positions the voltage between the red and green leads
is measured and displayed.

12

Loop Impedance measurement
Loop impedance measurement of 0,01Ω up to 3,00kΩ

can be made via installation sockets using the plug
terminated test lead, or at any other convenient point on
the installation using the two wire lead set. If Setting A
(see page 4) is selected when using the plug terminated
lead set, the polarity of the mains socket is immaterial.
Line and Neutral will be swapped if necessary, and an
indication given on the display. Setting b requires Line
and Neutral to be fixed.

Test results may be adversely affected by
supply voltage fluctuations or electrical noise
during measurement. It is recommended that

tests are repeated and the results verified, if

measurment results are considered abnormal.

The Installation Testers will measure the loop resistance
from the supply end of the standard test leads, allowing
for their resistance.

Automatic Testing

To aid rapid testing, the instruments can be set to
start a test automatically when connected to the
supply. This may be of use for example, when using
a clip and a probe. Select the range required and
press the test key without the supply present. The
instrument will display <100V for approximately
30 seconds. Apply the supply voltage within this time
and the instrument will pause before performing one
test automatically.

Phase to Neutral or Earth loop impedance measurement
(at a power socket):

1. Select Loop L-PE or L-N as required.

2. Insert the plug into an installation socket.

3. Supply voltage and polarity are displayed.

4. Press the TEST key.

5. Measured loop value is displayed.
On completion of this test, prospective fault current can

be displayed by pressing the ENTER key.
If desired the test can be repeated by pressing TEST

again.

Phase-Earth loop impedance measurement (not at a
power socket):

If an installation socket is not available, use the 3-wire
lead set.

1. Select Loop L-PE.

2. Connect the red lead to phase and the green lead to
earth. No connection to neutral is required.

3. Supply voltage is displayed.
Note: If the black lead is not connected to neutral,
although displayed the polarity indications are invalid.

4. Press the TEST key.

5. Measured loop value is displayed.

On completion of this test, the prospective fault current
can be displayed by pressing the ENTER key.

If desired the test can be repeated by pressing TEST
again.

Bonded Metalwork Testing (1)
This test is performed using the three wire lead set.

1. Connect the green lead to the bonded metalwork.

2. Connect the red lead to phase.

3. Select Loop L-PE.

4. Supply voltage is displayed.

5. Press the TEST key.

6. Measured resistance value is displayed.

13

Operation

Bonded Metalwork Testing (2)
This test can also be performed using the optional earth

bond test lead, allowing connection to an installation
socket.

1. Connect the black flying test lead to the bonded
metalwork.

2. Insert the power plug test lead into a socket
(receptacle).

3. Select Loop L-PE.

4. Supply voltage is displayed.

5. Press the TEST key.

6. Measured resistance value is displayed.

Phase-Neutral or Phase-Phase loop resistance
measurement

To measure the loop resistance of a circuit
Phase-Neutral, or between two phases of a multi-phase
system, connect using the 3-wire lead set.

1. Connect the red lead to phase and the black lead to
neutral or the other phase. There is no need to
connect the green lead.

2. Select Loop L-N/L-L.

3. The supply voltage is displayed. The polarity
indications are invalid and should be ignored.

4. Press the TEST button.

5. Measured loop resistance is displayed.

The prospective fault current may be displayed by
pressing the ENTER key.

14

Prospective Short Circuit Current measurement (PSCC)
The PSCC of a circuit is the largest Prospective Fault

Current (PFC). In a single phase system, this would be
the larger of the earth loop PFC and the neutral loop
PFC. In a multi-phase system phase-phase loops also
need to be considered and these can be measured
using the Loop L-L switch position.

When the instrument measures the loop resistance, it
also calculates the PFC. After any loop test, this may be
displayed by pressing the ENTER key.

The PFC is calculated by using the sum:-

The supply voltage used in the calculation depends on
the measured voltage and the configuration of the
instrument. As supplied, the instruments are configured
as follows:-

Actual Measured Voltage

>150V and <300V

Nominal supply voltage

Loop resistance

150V

>300V

Assumed Nominal Voltage

110V
230V
400V