A standard insulation tester is built for one test voltage — a CIE/444 configured for 500 V testing does 500 V testing, reliably, for its whole service life. A multirange insulation tester does the same job across several selectable test voltages from a single instrument. For a maintenance store or a contractor working across many equipment types, that difference decides how many testers you actually need to own. This guide explains what a multirange tester is and when it earns its higher cost over a fixed-voltage unit.
The Problem Multirange Solves
Different equipment classes call for different insulation test voltages — roughly 500 V for LV motors and cables, 1000–2500 V for MV equipment, up to 5000 V or beyond for HV apparatus (see our megger guide for the full test-voltage table). A maintenance team that services LV panels one day and MV switchgear the next either carries multiple fixed-voltage testers, or carries one multirange instrument that covers the whole span with a selector switch.
How a Multirange Tester Selects Voltage
A multirange hand-driven tester still generates its high voltage from the same crank-driven generator principle as a fixed-voltage unit, but routes the output through a selectable voltage-configuration stage — a series of pre-set combinations the operator dials in before testing, rather than the single fixed configuration of a standard model. Each series designation corresponds to a specific set of available test voltages, so specifying the right series when ordering matters as much as specifying the model itself.
The series designation is not optional detail
When Multirange Is Worth the Extra Cost
- Mixed-voltage maintenance work: Contractors and utility maintenance teams routinely testing LV, MV, and sometimes HV equipment in the same week get the clearest payoff — one instrument instead of two or three.
- Limited storage or transport capacity: Field teams carrying test kit to remote sites benefit from consolidating multiple voltage capabilities into one case.
- Commissioning teams testing varied equipment: EPC and substation commissioning work spans equipment from LV panels to HV switchgear on the same project — a multirange tester avoids swapping instruments between tasks.
When a Fixed-Voltage Tester Is the Better Choice
A team that only ever tests one class of equipment — say, LV motors exclusively, always at 500 V — gains nothing from multirange capability and pays for flexibility it will never use. A fixed-voltage instrument at the single voltage actually needed is simpler, and there's no series-selection step to get right at order time.
CIE manufactures the CIE/444/MR and CIE/666/MR hand-driven multirange insulation testers, and motorised multirange models for sustained PI/DAR testing across multiple voltage classes. Contact us to confirm the right series for your voltage range.