Electrical Inspection & Testing Guide: Insulation Resistance

Inspection and Testing. A.W.Croucher 2 004 page 37
Internal
If equipment disconnection is not a practical proposition, the controlling switch
may isolate equipment. But be sure to make an on-site assessment of the
chances of a switch line -neutral fault existing.
The insulation resistance tester shall be positioned - wherever practicable - at
the mains end of the distribution circuit or, alternatively, at the distribution
board bus bars.
P - E tests
All fuses are inserted. Current-using apparatus may remain connected,
assuming no N-E shorts exist. Controlling switches should be left on. The
previously stated results and qualifications are applicable.
Three-phase and neutral installations
Firstly, in the absence of a 4-pole isolator, the neutral shall be disconnected
from the incoming supply in order that a test may be conducted between
neutral and earth - neutral being at zero potential.
The test shall include the distribution circuit (sub main), with the IR tester
positioned at the main distribution board fuse/s.
Test of insulation resistance
between phase and cpc.
Fig.17