IR Value for Electrical cable and wiring:
- For insulation testing, we need to disconnect from panel or equipment and keep them isolated from power supply. The wiring and cables need to test for each other ( phase to phase ) with a ground ( E ) cable. The Insulated Power Cable Engineers Association (IPCEA) provides the formula to determine minimum insulation resistance values.
- R = K x Log 10 (D/d)
- R =IR Value in MΩs per 1000 feet (305 meters) of cable.
- K =Insulation material constant.( Varnished Cambric=2460, Thermoplastic Polyethlene=50000,Composite Polyethylene=30000)
D =Outside diameter of conductor insulation for single conductor wire and cable - ( D = d + 2c + 2b diameter of single conductor cable )
d – Diameter of conductor
c – Thickness of conductor insulation
b – Thickness of jacket insulation
HV test on new XLPE cable (As per ETSA Standard)
| Application | Test Voltage | Min IR Value |
| New cables – Sheath | 1KV DC | 100 MΩ |
| New cables – Insulation | 10KV DC | 1000 MΩ |
| After repairs – Sheath | 1KV DC | 10 MΩ |
| After repairs – Insulation | 5KV DC | 1000MΩ |
11kV and 33kV Cables between Cores and Earth (As per ETSA Standard)
| Application | Test Voltage | Min IR Value |
| 11KV New cables – Sheath | 5KV DC | 1000 MΩ |
| 11KV After repairs – Sheath | 5KV DC | 100 MΩ |
| 33KV no TF’s connected | 5KV DC | 1000 MΩ |
| 33KV with TF’s connected. | 5KV DC | 15MΩ |
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