A cold shrink termination is a pre-stretched silicone body that you slide over the cable end and let collapse into place, with no torch. TE Connectivity's Raychem CST line covers 15 to 35 kV polymeric cable in two versions: the CSTI for indoor use and the CSTO for outdoor use. This guide covers what each one does, how the part numbers break down, and how to pick the right size.

What is a Raychem CST cold shrink termination?

The CST is a cold applied termination for extruded cable, such as XLPE or EPR insulated cable. It connects the cable to a transformer, switchgear, an overhead line or a busbar. The body is liquid silicone rubber, supplied pre-expanded on a spiral holdout. You position it, pull out the holdout, and it shrinks onto the cable.

TE lists these features for the line:

• An extra long integrated stress control section, which makes positioning easier
• Built-in void filling and lug end sealing mastic, so no sealing tape or grease is needed
• High tracking and split resistance with good dielectric strength
• Hydrophobic silicone that resists UV, ozone, weathering, chemicals and fungus
• Non-flammable body
• Range-taking shear-bolt mechanical lugs available for the kit

The CST is qualified to IEEE 404 for the US versions, and TE publishes a separate CENELEC HD 629.1 version for IEC networks. TE lists an operating temperature range of -40 to 40 degrees C for the line and a 3 year shelf life.

What is the difference between CSTI and CSTO?

The I and O stand for indoor and outdoor.

Both use the same pre-expanded holdout approach and the same stress control design. If the termination will see rain, pollution or direct sun, choose the CSTO.

How do you read a CST part number?

Take CSTO-153G as an example.

• CSTO or CSTI: outdoor or indoor
• 15: the voltage class. 15 means 15 kV, 28 means 28 kV and 35 means 35 kV
• 3: the cable size range. 2 is the smallest range, then 3, then 4
• G or J: the cable shield. G is for copper tape shield and J is for JCN (jacketed concentric neutral) cable

Part numbers followed by a CL or CP suffix, such as CSTO-283G-CL4, are the same termination sold with a specific conductor size in mind. Contact us if you need one.

What sizes do the CSTO and CSTI come in?

From TE's data for the US versions. Conductor size is in AWG or kcmil and insulation diameter is in millimeters. Each CSTO size comes in a tape (G) and a JCN (J) version, and the sizes are the same for both. Part numbers without a link are TE catalog items we can order on request.

CSTO outdoor terminations

CSTI indoor terminations

More CST kits in our store

We also stock these CST kits, including the 35 kV class. TE does not list sizes for them on its public CST page, so contact us and we will confirm the conductor and insulation range before you order.

• CSTO outdoor: CSTO-352G, CSTO-352J, CSTO-353G, CSTO-354G
• CSTI indoor: CSTI-83G, CSTI-152J, CSTI-153J, CSTI-154G, CSTI-352G, CSTI-353G, CSTI-354G

How do you install a Raychem CST?

TE's installation video walks through a full CSTI or CSTO install for IEEE standard cable. The steps are the same idea every time: prep the cable and the shield, install the lug, slide the termination into position, and pull out the spiral holdout to let it shrink down. Always follow TE's instruction sheet in the kit for the exact dimensions.

Learn how to install our Raychem Cold Shrink Terminations CST for indoor and outdoor use up to 35 kV for IEEE standard networks.

Cold shrink or heat shrink termination: which should you use?

Both work. Cold shrink is the faster install, needs no torch and fits tight spaces, which is why it is common in switchgear compartments and on live-front pad-mounted gear. Heat shrink has a longer track record and shrinks to fit out-of-round cable. TE makes both, and we compare them in our Raychem splice guide. For splicing instead of terminating, see our CSJA cold shrink joint write-up.

How do I pick the right CST kit?

1. Indoor or outdoor. CSTI for protected spaces, CSTO if it sees weather.
2. Voltage class. 15, 28 or 35 kV, from the cable rating.
3. Shield type. G for copper tape shield, J for JCN cable.
4. Insulation diameter and conductor size. Measure the insulation OD and pick the kit whose range covers it, then check the conductor against the lug.
5. Lug. Mechanical shear-bolt lugs that take a range of conductor sizes are available for the line. Tell us your conductor and we will match it.

Frequently asked questions

What does CST stand for?

Cold Shrink Termination. The CSTI is the indoor version and the CSTO is the outdoor version.

What voltage are Raychem CST terminations rated for?

The US versions we stock cover 15, 28 and 35 kV classes. TE lists the line as qualified to IEEE 404 up to 35 kV.

Do you need a torch to install a CST?

No. It is pre-expanded on a spiral holdout. You pull the holdout out and the silicone body shrinks onto the cable.

What is the difference between the G and J versions?

G is for cable with a copper tape shield. J is for JCN cable, which has a jacketed concentric neutral. Insulation and conductor ranges are the same for a given size.

Can a CSTI be used outdoors?

No. The CSTI has no sheds and is meant for indoor use. Use the CSTO outdoors.

How long can a CST be stored?

TE lists a shelf life of 3 years.

Does the termination come with a lug?

Range-taking mechanical lugs are available for the CST line. Contact us to match one to your conductor.

Where can I buy Raychem CST terminations in New England or New York?

Powertech Associates and Utility Power Supply Company represent TE Connectivity across New England and New York State. Tell us the voltage, cable type and conductor size and we will help you pick the kit. Contact us at info@powertech-upsc.com or (860) 678-8772.