3M Cold Shrink Insulator 250-4...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$126.36
$74.41
3M Cold Shrink Insulator 250-400 kcmil EPDM Rubber Cable Protection System

3M Cold Shrink Insulator 250-400 kcmil EPDM Rubber Cable Protection System

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Model: 8427-12
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$126.36
$74.41
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3M Cold Shrink Insulator 250-400 kcmil EPDM Rubber Cable Protection System

Professional Cable Insulation & Mechanical Protection Solution

The 3M Cold Shrink Insulator delivers reliable primary insulation and mechanical protection for solid dielectric insulated wires and cable splicing applications rated to 1000 volts. Constructed from black EPDM rubber that contains no chlorides or sulfur, this professional-grade insulator provides superior sealing performance for terminal lug barrels, conduit couplings, and conduit-to-cable breakouts with simple tool-free installation.

Professional Features & Benefits

  • 250-400 kcmil Conductor Range: Accommodates large conductor sizes for high-capacity electrical installations and power distribution systems.
  • 1 kV Voltage Rating: Provides reliable primary insulation for low voltage applications with proven electrical performance standards.
  • EPDM Rubber Construction: Delivers superior weather resistance and durability with chloride-free and sulfur-free formulation for long-term reliability.
  • Cold Shrink Technology: Enables simple tool-free installation that eliminates the need for heat guns or torches, reducing installation time and complexity.
  • Wide Temperature Range: Operates reliably from -40�F to 194�F (-40�C to 90�C) for versatile environmental applications.
  • 12-inch Length: Provides ample coverage for comprehensive cable protection and splice insulation requirements.
  • USA Manufacturing: Ensures consistent quality and reliable supply chain for professional electrical applications.

Technical Specifications

  • Application: Insulation, mechanical protection, repair
  • Cable Shielding: Non-shielded|| Tape Shield|| UniShield�|| Wire Shield
  • Cable Type: Non-Shieled, Solid Dielectric Power Cable
  • Color Family Incorporate Product Color : Black
  • Conductor Material: Aluminum|| Copper
  • Conductor Size Range: 250-400 kcmil
  • Conductor Sizes: 125-200 mm_
  • Halogen Free: No
  • Inner Diameter After Shrink Imperial : 0.661 in
  • Inner Diameter After Shrink Metric : 16.8 mm
  • Inner Diameter Before Shrink Imperial : 1.382 in
  • Inner Diameter Before Shrink Metric : 35.1 mm
  • Manufacturer Catalog Number: 7000005943
  • Manufacturing Origin: USA
  • Maximum Connector Length: 8.0 in
  • Maximum Connector Length Metric : 203.2 mm
  • Maximum Operating Temperature Celsius : 90 Degree Celsius
  • Maximum Operating Temperature Fahrenheit : 194 Degree Fahrenheit
  • Minimum Operating Temperature Celsius : -40 Degree Celsius
  • Minimum Operating Temperature Fahrenheit : -40 Degree Fahrenheit
  • Number Of Conductors: 1
  • Overall Length Imperial : 12 in
  • Overall Length Metric : 304.8 mm
  • Package Height: 1.50000 in
  • Package Length: 20.00000 in
  • Package Weight: 0.3360 LBS
  • Product Material: EPDM Rubber
  • Product Voltage: 1 kV
  • Relaxed Tube Length: 12 in
  • Relaxed Tube Length Metric : 304.8 mm
  • Splice Type: Cold Shrink
  • Voltage Application: Low Voltage

Professional Applications

  • Power Distribution Systems
  • Industrial Electrical Installations
  • Commercial Building Infrastructure
  • Utility Substation Applications
  • Cable Splice Protection
  • Terminal Lug Insulation
  • Conduit Connection Sealing

Why Choose 3M Quality?

3M Cold Shrink Insulators provide proven reliability with USA manufacturing standards and EPDM rubber construction designed for long-term performance. The chloride-free and sulfur-free formulation ensures compatibility with electrical systems while delivering consistent protection across extreme temperature ranges from -40�F to 194�F.

Manufacturer Resources

Product Specs

Application:
Insulation, mechanical protection, repair
Cable Shielding:
Non-shielded|| Tape Shield|| UniShield®|| Wire Shield
Cable Type:
Non-Shieled, Solid Dielectric Power Cable
Color Family Incorporate Product Color :
Black
Conductor Material:
Aluminum|| Copper
Conductor Size Range:
250-400 kcmil
Conductor Sizes:
125-200 mm²
Halogen Free:
No
Inner Diameter After Shrink Imperial :
0.661 in
Inner Diameter After Shrink Metric :
16.8 mm
Inner Diameter Before Shrink Imperial :
1.382 in
Inner Diameter Before Shrink Metric :
35.1 mm
Manufacturer Catalog Number:
7000005943
Manufacturing Origin:
USA
Maximum Connector Length:
8.0 in
Maximum Connector Length Metric :
203.2 mm
Maximum Operating Temperature Celsius :
90 Degree Celsius
Maximum Operating Temperature Fahrenheit :
194 Degree Fahrenheit
Minimum Operating Temperature Celsius :
-40 Degree Celsius
Minimum Operating Temperature Fahrenheit :
-40 Degree Fahrenheit
Number Of Conductors:
1
Overall Length Imperial :
12 in
Overall Length Metric :
304.8 mm
Package Height:
1.50000 in
Package Length:
20.00000 in
Package Weight:
0.3360 LBS
Product Material:
EPDM Rubber
Product Voltage:
1 kV
Relaxed Tube Length:
12 in
Relaxed Tube Length Metric :
304.8 mm
Splice Type:
Cold Shrink
Voltage Application:
Low Voltage
Department:
Electrical

3M 8427-12 – Frequently Asked Questions

1) Will the 3M 8427-12 cold shrink insulator fit over a 350 kcmil cable and its lug barrel?
Yes. The 8427-12 covers conductors from 250 to 400 kcmil (125-200 mm2), so 350 kcmil sits in the middle of the range. It ships expanded at 1.382 in (35.1 mm) inside diameter, which is what has to slide over the connector and cable, and relaxes down to 0.661 in (16.8 mm) inside diameter once the core is pulled. Just confirm your connector body measures no more than 8.0 in (203.2 mm) long, since that is the largest connector the 12 in tube is sized to bridge.
2) Is the 3M 8427-12 cold shrink rated for medium voltage, or low voltage only?
Low voltage only. The 8427-12 is rated 1 kV and is intended as primary insulation on 600 V class and similar low voltage work. Do not put it on a 5 kV, 15 kV or 25 kV shielded cable splice or termination; that work needs a medium voltage cold shrink product built for it.
3) My connector is longer than 8 inches. Can I still use the 12 inch 8427-12 cold shrink?
No. The 8427-12 is sized for a connector up to 8.0 in (203.2 mm) long, because the 12 in tube has to land on undisturbed cable on both sides of the connector to seal. A longer lug or compression sleeve leaves no bearing surface at the ends, so you need a longer tube from the 8427 series instead of forcing this one.
4) Do I need a heat gun or torch to install a 3M 8427-12 cold shrink insulator?
No flame and no heat. It is a cold shrink tube: the EPDM sleeve is factory-expanded over a removable core, you position it over the connector or breakout, then pull the core out and the rubber contracts onto the cable on its own. That makes it usable in a manhole, a vault, or anywhere a hot work permit would otherwise be required for a heat shrink sleeve.
5) Can I use the 8427-12 cold shrink on aluminum conductor, or is it copper only?
Either one. The 8427-12 is listed for both aluminum and copper conductors, and it works on non-shielded solid dielectric power cable as well as tape shield, UniShield and wire shield constructions. It is sized for a single conductor, so one tube per conductor on a multi-run pull.
6) Will a 3M cold shrink insulator hold up outdoors in freezing weather or in a hot industrial space?
The 8427-12 runs from -40 F to 194 F (-40 C to 90 C), which covers outdoor northern winters and hot conduit runs in a plant or rooftop. The black EPDM rubber is the reason: it is weather resistant and formulated without chlorides or sulfur, so it is not corroding the connector it is sealed over.
7) What can I actually use an 8427-12 cold shrink tube for besides a splice?
Three common uses beyond straight splice insulation: sealing terminal lug barrels, sealing conduit couplings, and sealing a conduit-to-cable breakout. It is also used as a repair sleeve over damaged cable jacket. Any of those work because the 12 in (304.8 mm) relaxed tube shrinks tight to 0.661 in and seals against whatever it lands on.
8) Is there a halogen free version of the 3M 8427-12 cold shrink insulator?
The 8427-12 is not a halogen free product. If a project spec calls for halogen free materials in the tunnel, transit, or data center environment you are working in, this EPDM tube will not satisfy that line item and you need a product specifically listed as halogen free.
9) What is the 3M part number to order this 250-400 kcmil cold shrink insulator, and is it made in the USA?
Order it as 3M 8427-12. The manufacturer catalog number is 7000005943, and it is manufactured in the USA. The 8427 series is sized by tube length, and the -12 suffix is the 12 in (304.8 mm) tube covering 250-400 kcmil.
How fast can I get the 3M 8427-12 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the 3M 8427-12 come with a warranty?
Absolutely. The 3M 8427-12 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the 3M 8427-12?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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