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Checklist for Insulation Tests
C.3.1.1 Direct Connection (Earthing) Between Test Object and ISOTEST
With this method of earthing, the earthing cable supplied (15 m) is connected to the
tester via the earthing plug (see section C.3.1.2). The earthing clip at the other end
of the earthing cable is now attached to a conductive part of the test specimen.
Ensure that the point to which the earthing clip is fastened is metallically bare in order
to ensure a reliable connection.
C.3.1.2 Indirect Earthing With an Earthing Rod and Trailing Earth
Sometimes it is not possible to produce a direct connection between the ISOTEST
and conductive parts of the test object.
If the earth connection to the test object is a very long way away or is very difficult to
gain access to, as in the case of a train of pipes that is completely covered in
cladding, the earthing connection to the ISOTEST can probably be produced
indirectly via the ground:
Test object
(conductive) ground
ISOTEST
Indirect earthing can only be used if there is no doubt at all that the section
of the test object to be checked is genuinely well connected conductively to
the earthed end.
In the case of insulated sections between individual pipes it is only possible
to use indirect earthing if the segment to be tested is connected to the
ground!
The individual steps for indirect earthing
The test object is connected to the ground at a convenient point by means of an
earthing rod. Clamp the earthing pincers of the earthing rod to a bare metal point
on the test object and drive the earthing rod into the ground as far as possible.
Connect a trailing earthing cable to the ISOTEST. Insert the plug on the end of the
trailing earth cable into the earthing socket of the ISOTEST and spread the entire
length of the trailing earth cable out on the ground.
