3M 8427-12P Cold Shrink Insulator 8427-12P, Tape, Wire, Unishield, 1 kV, Standard, 100 per case

The 8427-12P shrinks down over cable or connectors in the 0.67 to 1.38 inch range (16.8 to 35.1 mm). Measure the largest point of your splice, usually the connector barrel, not the cable jacket. If the connector is fatter than 1.38 inches the tube will not slide on before the core is pulled; if the cable is thinner than 0.67 inches it won't grip and seal.

It covers 250, 300, 350 and 400 kcmil single-conductor power cable, aluminum or copper. It's a one-conductor insulator, so each splice in a multi-conductor run needs its own tube.

Up to 8.0 inches (203.2 mm) of connector length. Long-barrel compression lugs and splices run close to that, so check the barrel before you order: an 8 inch connector leaves you nothing to overlap onto the cable jacket at either end, and you need that overlap for the moisture seal.

Yes. The 8427-12P is rated for direct-buried and submersible secondary splices and dig-in repairs, and it seals moisture-tight as the EPDM rubber relaxes onto the cable. It's an open-ended tubular sleeve, so the seal is made by the rubber's grip on the jacket at both ends, which is why staying inside the 0.67 to 1.38 inch diameter range matters underground.

1 kV, so it's primary insulation for secondary splices up to 1000 volts on solid dielectric insulated wire and cable. It also gets used for physical protection of high-voltage air-insulated connectors or lugs, and for plain environmental sealing on communication and other non-electrical work, but the electrical insulation rating itself is 1 kV.

It's the insulating sleeve only. You make the joint first with a compression splice or lug sized to your conductor, then cover it. For 250 to 400 kcmil copper, a long barrel compression splice such as the Burndy YS6C Hylink is the type of connector this insulator is built to cover, as long as the finished barrel stays under 8 inches and within the 1.38 inch diameter limit.

They do different jobs and are typically used together. The 3M 8427-12P is a cold shrink insulator - it is the insulating and environmental sealing sleeve that goes over a completed splice, rated 1 kV and accommodating 250, 300, 350 and 400 kcmil conductors on aluminum or copper. The Burndy YS6C Hylink is a long barrel copper compression splice, meaning it is the metallic connector that mechanically joins the conductors. If you are making up a secondary splice, you crimp a connector such as the Hylink and then cover it with the cold shrink insulator; buying the 8427-12P alone does not give you the conductor connection.

No heat and no tools. Cold shrink means the tube ships pre-expanded on a removable core; you slide it into position over the splice and pull the core ribbon out, and the rubber contracts on its own. That makes it the practical choice in a trench, a vault, or anywhere an open flame isn't allowed, unlike heat shrink tubing that needs a torch.

Both. The 8427-12P is listed for non-shielded, tape shield, UniShield and wire shield constructions on power cable. It is an insulator over the splice, not a shield-continuity component, so shield bonding still has to be handled separately per your standard.

RoHS 2011/65/EU compliant without exemption, and ANSI certified. Manufacturing origin is listed as USA, meaning substantial transformation happens in a U.S. plant, though some components may be imported. For government contract work requiring a country of origin representation, 3M Trade Compliance issues the certificate through 3M customer service at 800-245-3573.

The 3M 8427-12P is rated for both aluminum and copper conductors at 250 through 400 kcmil, so the insulator itself is not a limitation on an aluminum run. The connector is where conductor material matters: the Burndy YS6C Hylink is a copper compression splice. On an aluminum or aluminum-to-copper joint you would select a connector rated for that metal combination and then still cover the finished splice with the 8427-12P cold shrink sleeve, which handles either.

Minus 40 to 194 degrees F (-40 to 90 C). The EPDM rubber also resists ozone, acids and alkalis and contains no chlorides or sulfur, which is why it holds up in buried and submerged locations rather than hardening and cracking.

10 per case. Each tube covers one conductor, so a three-phase splice set consumes three of them, plus one more if you're insulating a neutral.