If you're specifying medium-voltage feeder or distribution cable, you've probably seen "MV-105" on a spec sheet and wondered what the number refers to. It's simpler than it looks, and knowing what it means keeps you from over-buying or under-specifying the next job.
Breaking Down the Name
- MV stands for Medium Voltage, generally cable rated above 2,000 volts. Common classes are 5kV, 15kV, 25kV, and 35kV.
- 105 is the maximum continuous conductor operating temperature in Celsius.
MV-105 cable runs continuously at 105°C, where the older MV-90 tops out at 90°C. Those 15 degrees translate directly into ampacity: MV-105 carries more current through the same conductor size before hitting its thermal limit.
The full temperature picture has three thresholds:
| Condition | Max Conductor Temp |
|---|---|
| Continuous operation | 105°C |
| Emergency overload | 140°C |
| Short circuit | 250°C |
Construction
MV-105 is a layered system, typically built up as:
- Conductor: annealed stranded copper or aluminum
- Conductor shield: semi-conducting layer that manages electrical stress
- Insulation: EPR or TR-XLPE, chosen for dielectric strength and moisture resistance
- Insulation shield: strippable semi-conducting layer for clean terminations
- Metallic shield: copper tape providing a fault-current and grounding path
- Jacket: sunlight-resistant, flame-retardant PVC (CPE and LLDPE jackets are available for tougher chemical or moisture exposure)
Where It's Used
- Utility primary distribution (12.47kV / 13.8kV feeders)
- Industrial plants: refineries, chemical plants, and steel mills feeding large motors and switchgear
- Direct burial, duct, tray, and aerial installations
- Commercial and industrial service entrances
Standards to Look For
Legitimate MV-105 cable should carry:
- UL 1072
- ICEA S-93-639 / NEMA WC74
- AEIC CS8 (EPR) or CS9 (XLPE/TR-XLPE) on utility-grade jobs
- IEEE 383 / 1202 flame testing on larger conductor sizes
MV-105 vs MV-90: Which Do You Need?
If you're fighting ampacity limits on an existing conductor size, running feeders in a hot environment, or specifying new utility or industrial work, MV-105 has largely become the default rather than the upgrade. MV-90 still shows up in older installations and replacement-in-kind jobs, but most new specs call for 105°C-rated cable.
Get the Right MV-105 Cable for Your Job
Mid America Wire & Cable stocks power cable across major manufacturers and standards, with same-day dispatch to all 50 states. If you're specifying MV-105 for an upcoming project, browse our catalog or request a quote and our technical sales team can help confirm voltage class, conductor size, and insulation type before you order. Or call us directly at (918) 622-1489.
