HT instruments MACROTEST 5035 - Manual (Page 68)

MACROTEST 5035
EN - 67
Check the continuity among:
a) earth poles of
all the plugs and earth collector or node.
b) earth terminals of class I instruments (Boiler etc.) and earth collector or node.
c) main external masses (water, gas pipes etc.) and earth collector or node.
d) auxiliary
external masses to the earth terminal.
ALLOWABLE VALUES
The standards CEI 64-8/6 do not give any indication on the maximum resistance values
which cannot be overcome, in order to be able to declare the positive outcome of the
continuity test.
The standard CEI 64-8/6 simply requires that the instrument in use warns the operator if
the test was not carried out with a
current of at least 0.2 A and an open circuit voltage
ranging from 4 V to 24 V.
The resistance values can be calculated according to the sections and lengths of the
conductors under test, anyway if the instrument detects values of some ohm the test can
be considered as passed.
11.2. INSULATION RESISTANCE MEASUREMENT
PURPOSE OF THE TEST
Check that the insulation resistance of the installation complies with the requirements of
standards CEI 64-8/6.
NOTA: This test is to be effected on an open circuit with any load disconnected.
INSTALLATION PARTS TO BE CHECKED
a) Between each active conductor and the earth (the neutral conductor is considered an
active conductor except in the case of TN-C systems where it is considered part of the
earth (PEN). During this measurement all active conductors can be connected to each
other, in case the measurement result does not fall within the standard limits the test is
to be repeated for each single conductor.
b) Among active conductors. The standard CEI 64-8/6 recommends to check the
insulation among the active conductors when this is possible (ATTENTION).
ALLOWABLE VALUES
The values of test voltage and minimum insulation resistance are reported in the following
table (CEI64-8/6 Tab. 61A):
Rated circuit voltage (V) Test voltage (V) Insulation resistance (M Ω)
SELV and PELV* 250
≥0.250
Up to 500 V included, except for the
above circuits.
500
≥0.500
Over 500 V 1000
≥1.000
* In the new standards the terms SELV and PELV replace the old definitions "safety low
voltage" or "functional".
Test voltage values and relative limit values for the most common kinds of test.