DET2/3
2
Safety
Live earth safety precautions
A 'Live' earth is one that carries current from the mains supply, or could do so under fault conditions. The
following warnings apply in addition to those listed previously:
All persons involved must be trained and competent in isolation and safety procedures for the system to be
worked on. They must be clearly instructed not to touch the earth electrode, test stakes, test leads, or their
terminations, if any 'live' earths may be encountered. It is recommended that they wear appropriate rubber
gloves, rubber soled shoes, and stand on a rubber mat
The earth electrode under test should be isolated from the circuit it protects before a test is started. If this is
not possible, ART may be used to measure electrode resistance
The instrument terminals should be connected to the system under test through isolation switches. The
isolation switches must be rated to handle the likely maximum fault voltages and currents that could be
encountered at the installation.
The isolation switch must be open when any physical contact is made with the remote test stakes, or the
connecting leads, for example, when changing their position
The instrument terminals should be connected to the system under test through fuses, that are rated to
handle the likely maximum fault voltages and currents that could be encountered at the installation
Voltage measurement categories
The rated measurement connection voltage is the maximum line to earth voltage at which it is safe to connect.
CAT IV
Measurement Category IV: Equipment connected between the origin of the low-voltage Mains supply and the
Distribution Panel.
CAT III
Measurement Category III: Equipment connected between the Distribution Panel and the electrical outlets.
CAT II
Measurement Category II: Equipment connected between the electrical outlets and the User’s equipment.
Measurement equipment may be safely connected to circuits at the marked rating or lower. The connection rating
is that of the lowest rated component in the measurement circuit.
Test leads and clamps
Megger supply test leads designed for the DET2/3 which are rated correctly for the test voltage generated by this
instrument, but not all are rated for mains connection. Users must select the correct leads for their project, this
will be either low voltage type rated 50 V, 1 A or leads designed for mains environment rated at 300 V.
Caution: Measurement leads connected to this instrument must be rated at least 50 V, 1 A.
The terminals for connecting current and voltage clamps are not isolated from the measurement terminals. If the
DET2/3 is used in a CAT IV 300 V environment, the clamps and their measurement leads must be rated the same
or higher. Only the Megger MCC1010 and Megger MVC1010 are sufficiently rated, no other clamps are to be
used.
www.calcert.com
sales@calcert.com
1.800.544.2843
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