Garrie AI: Your Cable Guide
MV-90 vs MV-105 in High-Density Power Applications
As data centers and renewable energy projects handle growing power demands, medium-voltage cables must carry higher loads through increasingly crowded pathways. The 15°C difference in continuous conductor temperature between MV-90 and MV-105 can affect ampacity, conductor sizing, and future expansion capacity. This guide compares their ratings, insulation, code requirements, and costs to help determine which cable is better suited for high-density power distribution.
What MV-90 and MV-105 Mean
MV-90 and MV-105 refer to the maximum continuous operating temperature of a medium-voltage cable's conductor. MV-90 is rated for up to 90°C, while MV-105 is rated for up to 105°C. Both are available in common medium-voltage classes, including 5 kV, 15 kV, 25 kV, and 35 kV.
The rating must be supported by the cable's listing and markings. Some cables use insulation capable of withstanding 105°C but are only marked MV-90, so they cannot automatically be treated as MV-105 in ampacity calculations.
MV-90 vs MV-105 Cable Compared
Insulation: XLPE vs. EPR
Both MV-90 and MV-105 cables can use cross-linked polyethylene (XLPE) or ethylene propylene rubber (EPR) insulation. XLPE is generally lighter, stiffer, and less expensive, making it a practical choice for long cable runs. EPR is more flexible and easier to work with in tight spaces, particularly around bends and crowded terminations.
The insulation material doesn't automatically determine whether a cable is rated for 90°C or 105°C. Both ratings are available with either material, so check the specifications of the cable you're buying.
Ampacity and Thermal Headroom Under NEC Article 315
MV-105 can carry more current than MV-90 at the same conductor size because it can operate at a higher temperature. For example, a 750 kcmil copper conductor in a properly spaced, uncovered cable tray has an ampacity of 990 A at 105°C, compared with 870 A at 90°C. That's approximately 14% more capacity without increasing conductor size.
For this reason, MV-105 is better suited for crowded duct banks, hot electrical rooms, and cable trays with multiple circuits, where heat buildup can reduce allowable ampacity.
Even though MV-105 can carry more current under normal operating conditions, it doesn't offer better protection against short circuits. Both MV-90 and MV-105 have the same 250°C short-circuit temperature limit, so they require the same conductor size to withstand a given fault current.
Check fault current and termination ratings before using MV-105's higher ampacity to reduce conductor size.
Emergency Overload Ratings
MV-105 can withstand conductor temperatures of up to 140°C during emergency overloads, compared with 130°C for MV-90. This provides additional flexibility when a feeder temporarily carries extra load, such as during a utility outage, equipment failure, or switch to backup power.
These ratings apply only to temporary conditions, not continuous operation. ICEA standards limit how long cables can operate at emergency temperatures, so check the manufacturer's specifications before relying on this additional capacity.
MV-90 vs MV-105 in Data Center Applications
AI data centers are bringing medium-voltage power distribution closer to computing equipment as rack power demands increase. Instead of stopping at outdoor substations, MV feeders increasingly extend into electrical rooms and power distribution areas near data halls.
According to IAEI, large data centers typically use medium-voltage systems ranging from 4.16 kV to 34.5 kV. New equipment is making these configurations more practical. ABB's 34.5 kV HiPerGuard UPS, for example, provides medium-voltage protection without requiring a separate low-voltage UPS stage.
How Far Does Medium-Voltage Cable Go Inside Data Centers?
Medium-voltage cable generally supplies UPS systems, transformers, and rectifiers in dedicated electrical rooms or power blocks. The final connection to the server racks remains low-voltage.
The exact arrangement depends on the facility's power architecture. NVIDIA's 800 VDC reference design, for example, converts 13.8 kV AC to 800 VDC at the facility perimeter, then distributes DC power to computing equipment. Other designs bring medium voltage closer to individual data halls before converting it to low voltage.
As rack densities increase, these arrangements help reduce the amount of low-voltage cabling needed to distribute large amounts of power. However, medium-voltage equipment generally remains outside the IT space, in separate electrical rooms.
What This Means for MV-90 vs. MV-105 Cable Selection
Bringing medium voltage closer to computing equipment can mean more cable runs through electrical galleries, crowded cable trays, and rooms containing heat-producing equipment.
MV-105 can be useful in these conditions because its higher operating temperature rating provides additional ampacity where heat buildup restricts cable capacity. It may also help accommodate future load increases without installing additional conductors.
Other installation requirements remain important. EPR insulation can make routing cable through tight bends and crowded terminations easier, while indoor installations may call for low-smoke, zero-halogen jackets.
MV-105 isn't automatically necessary for every data center feeder. MV-90 remains a practical choice where cable spacing, ambient temperatures, and expected loads allow it to meet ampacity requirements without excessive derating.
Which Cable For Each Segment Of Data Center
|
Segment |
Typical Voltage |
Thermal stress |
Cable Choice |
|
Utility service to main MV switchgear |
13.8 kV to 34.5 kV |
High: many circuits share one duct bank |
MV-105, or MV-90 when the bank has spare ducts and spacing |
|
Generator plant to paralleling switchgear |
4.16 kV to 13.8 kV |
High: hot yards, full output during outages |
MV-105 |
|
MV switchgear to MV UPS and unit substations |
13.8 kV to 34.5 kV |
High: stacked tray in hot electrical galleries |
MV-105 EPR |
|
Campus loop between buildings |
13.8 kV to 34.5 kV |
Moderate: redundant loops run partly loaded |
MV-90 TR-XLPE |
|
Indoor MV to MV UPS, rectifier blocks, and 800 VDC power rooms beside the data hall |
13.8 kV to 34.5 kV |
High: indoor heat, tight bends, occupied space |
MV-105 EPR with a low smoke, zero halogen jacket |
MV 105 vs MV 90: How to Choose
Choose MV-105 for installations where heat buildup limits the current the cable can carry, such as high-density data centres and hot industrial facilities. MV-90 is generally sufficient for lighter loads and installations with adequate spacing and ventilation, such as conventional utility feeders and less heavily loaded industrial circuits.
MV-90 is usually enough when:
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The run is direct-buried or in a duct bank with spare ducts and adequate spacing.
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Soil thermal resistivity is known and favorable.
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The feeder runs partly loaded most of its life, as in utility URD or redundant campus loops.
-
Long, straight runs make XLPE's lower loss and price the bigger win.
-
Fault withstand, not ampacity, sets the conductor size. MV-105 cannot shrink it.
MV-105 earns its premium when:
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Several loaded circuits share one duct bank or one tray.
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Ambient air runs hot: electrical galleries, rooftops, generator yards, spaces near cooling plant.
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The design is close to adding a parallel set or the next conductor size.
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The owner expects load growth, such as a data hall planned for denser racks.
-
A contingency operation, such as a loop picking up a failed section, can push conductors toward the emergency temperature.
Source MV-90 and MV-105 Cable from NNC
Nassau National Cable stocks MV-90 and MV-105 cable from 2.4 kV through 35 kV across four U.S. warehouse locations, backed by strategic factory stock allocations and direct relationships with Southwire, Prysmian, and Okonite. NNC cuts to length, builds custom reel configurations, matches parallel sets, and supplies pre-terminated assemblies with lugs installed. NNC works as a primary supplier or as a backup source when a critical-path feeder cannot wait.
Pick the rating first, then the voltage class. The full medium voltage collection and our 5 kV vs 15 kV vs 35 kV selection guide list every product by voltage.
MV-105 cable
-
15 kV Okonite Okoguard MV-105 with low smoke, zero halogen jacket for indoor and data center runs
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15 kV Prysmian Airguard MV-105, three-conductor EPR/PVC, 133%
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25 kV / 35 kV Type UL MV-105 EPR, PVC jacket, single conductor
MV-90 cable
Dual-marked MV-105 or MV-90 cable
Need terminations too? See MV terminations and accessories.
Call 516-482-6313 or request a quote for your next medium voltage feeder.
FAQ
What is the difference between MV-90 and MV-105 cable?
MV-90 cable is rated for 90°C continuous, 130°C emergency overload, and 250°C short circuit. MV-105 cable is rated for 105°C continuous, 140°C emergency overload, and 250°C short circuit. The higher rating provides MV-105 with greater ampacity for the same conductor size.
Can MV-105 cable replace MV-90 cable?
In most cases, yes. A cable with a higher temperature rating can go where MV-90 is specified, provided the voltage class, insulation level, shield, and jacket match the design. The engineer of record should still approve the substitution.
Is MV-90 cable XLPE or EPR?
Most MV-90 cables use XLPE or TR-XLPE insulation, but EPR versions are also available. The UL 1072 marking on the jacket, not the insulation type, sets the rating.
Is MV-90 cable meant for cooler environments?
No. Both ratings describe the maximum conductor temperature, which is the ambient heat plus the heat generated by the load current. Ambient temperature enters the design through correction factors under Tables 315.60(C)(1) through (C)(20). MV-90 works in hot spaces when sized for derated ampacity. MV-105 starts with more headroom.
Is medium-voltage cable used inside AI data centres?
Increasingly, yes. MV cable now runs indoors to MV UPS systems, transformers, and rectifier or 800 VDC power blocks in grey space beside the data hall. The final run to the racks is still low voltage, at 415 VAC or 800 VDC, because MV equipment cannot yet sit directly inside the IT room.
Which NEC article covers MV-90 and MV-105 cable?
NEC Article 315 in the 2023 edition, titled Medium Voltage Conductors, Cable, Cable Joints, and Cable Terminations. The 2020 NEC covered the same material in Article 311. Ampacities are in Tables 315.60(C)(1) through (C)(20).
Can I use the 105°C ampacity if my terminations are rated 90°C?
NEC 110.40 bases terminations over 1,000 V on the 90°C rating and ampacity unless the equipment is identified otherwise. Confirm the equipment rating and agree on the approach with the engineer of record and the AHJ.
Is MV-105 better for data centers?
For congested duct banks, hot electrical galleries, generator feeders, and MV runs near the data hall, MV-105 is usually the stronger choice. For lightly loaded campus loops with spare pathway capacity, MV-90 often does the job at lower cost.
How big is the MV-105 cable market?
Market Research Future estimates the global MV 105 cable market at $1.5 billion in 2024 and projects $3.0 billion by 2035.
