Minimum insulation resistance values depend on the nominal voltage (IEC/HD 60364-6): In 230/400 V installations, a minimum of 1.0 MΩ is required with a 500 V DC test.; 0.5 MΩ with 250 V test in SELV/PELV; 1.0 MΩ with 1000 V test above 500 V.
≤500 V → 500 V DC test, ≥ 1.0 MΩ · SELV/PELV → 250 V, ≥ 0.5 MΩ
Example calculation: 400 V circuit → 500 V DC test, minimum 1.0 MΩ; suitable if measured at 2.5 MΩ.
Insulation (Megger) Resistance Limit Values
Check the applicable test voltage and minimum insulation resistance based on the circuit's nominal voltage; compare this to your measured value.
Test voltage
–
Minimum insulation resistance
–
Notes: The values are IEC/HD 60364-6 (Table) insulation resistance minimums: SELV/PELV → 250 V DC test, ≥ 0.5 MΩ; ≤ 500 V → 500 V DC test, ≥ 1.0 MΩ; > 500 V → 1000 V DC test, ≥ 1.0 MΩ. Measurements are performed separately for phase-to-ground and phase-to-phase; final evaluation depends on field conditions.
How is it calculated?
- Select the circuit's nominal voltage range.
- (Optional) Enter the insulation resistance (MΩ) you measured.
- Press Evaluate; the threshold value and eligibility will be displayed.
Frequently Asked Questions
What should the Megger value be in MΩ?
For 230/400 V installations, a minimum of 1.0 MΩ (500 V DC test) is required. For SELV/PELV circuits, 0.5 MΩ is sufficient.
What voltage is used to measure insulation resistance?
Depending on the nominal voltage: SELV/PELV 250 V, 500 V for ≤500 V, 1000 V DC test voltage for >500 V is applied.
What does low insulation resistance mean?
The insulation may be affected by moisture, contamination, or deterioration; the source of the problem should be investigated and rectified.
Related tools and services
This tool and its content are for general informational purposes only; they do not constitute a binding inspection/declaration of conformity. Definitive results will be determined through on-site inspection in accordance with relevant legislation and standards. Get a quote →