25kV Class Equipment.
The suburban and rural utility distribution class — covering 24.94 kV nominal system voltage, rated and stocked across accessory lines as 25/28 kV, with standard BIL of 125 kV per IEEE C57.12.00.
- Equipment categories
- 10
- Nominal voltage
- 24.94 kV
- Standard BIL
- 125 kV
Standards.
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IEEE C57.12.00
Liquid-immersed transformer general requirements — defines 25kV class BIL at 125 kV.
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IEEE C37.20.2
Metal-clad switchgear standard for indoor and outdoor 25kV class switchgear.
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IEEE 386
Separable connectors — 200A and 600A elbows rated and cataloged as 25/28 kV class on pad-mount transformers.
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IEEE 404
Extruded and laminated dielectric shielded cable joints (splices) rated for 25kV systems.
Equipment categories rated for 25kV.
Transformers
Distribution and power transformers — pad-mounted, dry-type, and substation units rated for 25kV class.
View categorySwitchgear
Metal-clad and metal-enclosed switchgear per IEEE C37.20.2 for 25kV indoor and outdoor installations.
View categoryCable Splices
Cold-shrink and heat-shrink splices for 25kV cable joints per IEEE 404.
View categoryCable Terminations
Indoor and outdoor terminations for 25kV cable ends at transformers, switchgear, and substations.
View categoryElbow Connectors
200A loadbreak and 600A deadbreak elbow connectors per IEEE 386 — cataloged as 25/28 kV class at pad-mount transformers.
View categoryJunction Cabinets
Pad- and vault-mounted cabinets housing 25kV underground distribution taps.
View categoryMetering Equipment
Pad- and pole-mounted revenue metering equipment for 25kV-class utility service.
View categoryFault Indicators
Overhead and underground fault indicators for 25kV distribution circuits.
View categorySurge Arresters
Distribution and intermediate class arresters sized for 25kV system MCOV and energy class.
View categoryTransmission & Distribution Products
Line hardware and insulators for 25kV overhead distribution circuits.
View categoryMedium-voltage classes.
In-plant industrial distribution and large motor feeders. 2.4-4.8 kV, 60 kV BIL.
View class 15kVThe dominant utility primary-distribution class. 12.47-13.8 kV, 95 kV BIL.
View classSuburban and rural utility distribution. 24.94 kV (25/28 kV), 125 kV BIL.
You are hereCollector systems and long rural feeders. 34.5 kV, 150 kV BIL.
View classFAQ.
What nominal system voltage does the 25kV class cover?
The 25kV class is applied to a nominal system voltage of 24.94 kV — a suburban and rural utility distribution voltage. Across cable accessory lines the class is rated and cataloged as 25/28 kV, so a single accessory family covers both designations.
The class designation refers to the equipment insulation rating, not the actual operating voltage. A “25kV class” transformer is rated for a maximum system voltage in that range, with standard BIL of 125 kV per IEEE C57.12.00.
What is the standard BIL for 25kV class equipment?
Standard BIL for 25kV class equipment is 125 kV per IEEE C57.12.00. BIL — Basic Impulse Insulation Level — is the equipment's specified ability to withstand a standard impulse voltage wave without insulation breakdown.
It is coordinated with the surge arresters on the system. 25kV-class separable connectors and cable accessories carry the same 125 kV BIL across the 25/28 kV rating.
Why is the 25kV class cataloged as 25/28 kV?
Manufacturers of separable connectors and cable accessories rate a single product family for both 24.94 kV and 26.4 kV systems, so the catalog designation is written as 25/28 kV. The accessory covers the full class with one part number range rather than separate lines.
Eaton, Hubbell, and ABB (Elastimold) all publish 25/28 kV IEEE 386 elbow connector lines on this basis. Hawk states the designation as the manufacturers do; exact ratings are confirmed at quote.
Where is the 25kV class used?
The 25kV class is a suburban and rural utility primary-distribution class. Its higher voltage relative to 15kV lets a feeder carry the same power over longer distances with lower line losses, which suits the lower load density and longer runs of suburban and rural systems.
Utilities that standardize on 24.94 kV use 25kV-class pad-mount transformers, switchgear, separable connectors, and underground cable accessories throughout the distribution system.
What standards govern 25kV class equipment?
Liquid-immersed transformers — including pad-mount and substation units — are governed by IEEE C57.12.00 (general requirements) and C57.12.34 (three-phase pad-mounted compartmental). Dry-type units use IEEE C57.12.01.
Switchgear is governed by IEEE C37.20.2 (metal-clad) or C37.20.3 (metal-enclosed). Separable connectors use IEEE 386 (200A and 600A elbows, cataloged 25/28 kV). Cable splices and terminations use IEEE 404 and IEEE 48. Surge arresters use IEEE C62.11.
Sourcing 25kV equipment?
Send the category, nominal voltage, BIL, and quantities for a quote.
25kV class equipment for utility distribution.
The 25kV class is a suburban and rural utility primary-distribution class. It covers a nominal system voltage of 24.94 kV and is rated and cataloged across cable accessory lines as 25/28 kV, so one accessory family covers both designations. The higher voltage relative to the 15kV class lets a feeder carry the same power over longer distances with lower line losses — a fit for the lower load density and longer runs of suburban and rural systems. Equipment in this class is built to IEEE C57.12.00 for liquid-immersed transformers, IEEE C37.20.2 for metal-clad switchgear, IEEE 386 for separable connectors, IEEE 404 for cable splices, and IEEE C62.11 for surge arresters, with standard BIL of 125 kV.
Hawk MV Supply sources 25kV-class equipment across 10 product categories — transformers, switchgear, cable splices and terminations, elbow connectors, junction cabinets, metering equipment, fault indicators, surge arresters, and transmission & distribution products. 25kV-class MV cable for 100% insulation level commonly uses a 260 mil insulation wall on grounded distribution systems. Contact us to develop part numbers and check stock and lead time across the linecard.