Insulation & Installation Testers

This category covers everything from 1 kV installation testers used daily by electrical contractors through to 15 kV diagnostic megohmmeters for generators and transmission cable.

Match the test voltage to the equipment

The convention is roughly twice rated voltage plus 1000 V. General installation work up to 1000 V is fully covered by a 1 kV instrument; medium-voltage cable, large motors and generators need 5 kV or above.

Applying 5 kV to equipment rated for 400 V does not produce a better test — it risks damaging insulation that was healthy.

Test current and diagnostics

Maximum voltage says nothing about whether the instrument can hold that voltage into a real capacitive load. Instruments intended for large plant specify several milliamps of test current for this reason.

Diagnostic modes matter for rotating machines: polarisation index, dielectric absorption ratio, dielectric discharge and step voltage all reveal deterioration that a single resistance reading misses.

Common questions