8.3.1 - Why is correct sequence important?
Testing can be hazardous, both to the tester
and to others who are within the area of the installation
during the test. The danger is compounded if tests are not
carried out in the correct sequence.
For example, it is of great importance
that the continuity, and hence the effectiveness, of protective
conductors is confirmed before the insulation resistance
test is carried out. The high voltage used for insulation
testing could appear on all extraneous metalwork associated
with the installation in the event of an open-circuit protective
conductor if insulation resistance is very low.
Again, an earth-fault loop impedance test
cannot be conducted before an installation is connected
to the supply, and the danger associated with such a connection
before verifying polarity, protective system effectiveness
and insulation resistance will be obvious.
Any test which fails to produce an acceptable
result must be repeated after remedial action has been taken.
Any other tests, whose results may have been influenced
by the fault concerned must also be repeated.