When working with electrical cable splices, terminations, and underground distribution systems, choosing the right heat shrink tubing is essential for reliable insulation, moisture protection, and long-term cable performance. Two popular options from TE Connectivity's Raychem product line are WCSM heavy-wall heat shrink tubing and MWTM medium-wall heat shrink tubing.
The primary difference between Raychem WCSM and MWTM is wall thickness and shrink ratio. WCSM is a heavy-wall tubing designed for demanding sealing, mechanical protection, and cable jacket repair applications. MWTM is a medium-wall tubing that provides a balance of electrical insulation, moisture sealing, and mechanical protection in a more compact profile.
Both products are designed for use in electrical power systems, but understanding their differences can help utility professionals, electrical contractors, and distributors select the appropriate solution for each application.
Raychem WCSM is heavy-wall, heat-shrinkable tubing designed for cable sealing, protection, and jacket restoration. Manufactured by TE Connectivity, WCSM uses cross-linked polyolefin technology and is available with an internal hot-melt adhesive coating to provide a moisture-resistant seal when properly installed.
Its heavy-wall construction makes it well suited for applications where mechanical protection and environmental sealing are important.
WCSM is particularly useful when a cable repair or splice requires a substantial protective covering. Its heavy-wall construction makes it a strong option for demanding utility and industrial environments.
Actual suitability depends on the specific product size, construction, and application requirements.
Raychem MWTM is medium-wall heat shrink tubing designed to provide electrical insulation, moisture sealing, and mechanical protection for power cables and cable accessories.
Like WCSM, MWTM is manufactured from cross-linked polyolefin and is available in configurations with or without an internal hot-melt adhesive coating, depending on the product.
Its medium-wall construction provides a balance between protection and flexibility, making it suitable for a wide range of cable applications.
MWTM is a practical option when a utility needs reliable insulation or cable protection without necessarily requiring the heavier construction of WCSM.
As with WCSM, the correct product must be selected according to cable dimensions, voltage-related requirements, and the intended application.
Although both products belong to the Raychem heat shrink tubing family, they are designed with different construction characteristics and application priorities.
| Feature | Raychem WCSM | Raychem MWTM |
|---|---|---|
| Product type | Heavy-wall heat shrink tubing | Medium-wall heat shrink tubing |
| Wall construction | Heavier protective wall | Medium protective wall |
| Typical shrink ratio | 4:1 | Approximately 3:1 |
| Primary purpose | Robust sealing, protection, and jacket restoration | Insulation, sealing, and cable protection |
| Adhesive options | Adhesive-coated configurations | Adhesive-coated and uncoated configurations |
| Moisture sealing | Yes, with the appropriate coated product | Yes, with the appropriate coated product |
| Cable jacket repair | Suitable for specified applications, including certain cables up to 35 kV | Suitable for specified rejacketing applications, including certain cables up to 35 kV |
| Low-voltage applications | Cable accessory insulation and sealing | Cable accessory insulation and sealing |
| Installation profile | Generally more substantial | Generally more compact |
| Best selection criteria | Greater wall thickness and protection requirements | Balance of protection, insulation, and profile |
Note: Shrink ratios and available configurations should be confirmed against the specific catalog number and current product documentation. Neither product should be assumed suitable for every voltage class or cable construction.
One of the most important differences between WCSM and MWTM is their wall construction.
WCSM's heavy-wall design provides a more substantial protective layer around the cable or connection. This can be advantageous where the tubing must withstand demanding environmental conditions or provide robust coverage over a repaired cable jacket.
MWTM's medium-wall design offers a balance of mechanical protection and a less substantial installed profile.
Which is better? If the application calls for heavy-wall protection, WCSM may be the better choice. If medium-wall construction meets the application requirements, MWTM may provide the desired protection with a more compact installation.
The appropriate choice depends on the cable, installation environment, and required performance rather than wall thickness alone.
Shrink ratio is another important consideration when choosing heat shrink tubing.
Raychem WCSM generally has a 4:1 shrink ratio, while MWTM generally has a 3:1 shrink ratio. A higher shrink ratio allows the tubing to accommodate a wider range of diameters. This can be particularly useful when covering connectors, splices, or cable sections with varying dimensions.
For example, a repair involving a large connector body and a smaller cable jacket may benefit from the greater diameter range available in an appropriately sized WCSM product.
MWTM can also accommodate a range of diameters, but the expanded and recovered dimensions of the specific part must be checked to ensure a proper fit.
Important: Shrink ratio alone does not determine compatibility. Always verify the tubing's expanded diameter, recovered diameter, recovered wall thickness, and the dimensions of the cable or connector.
Both WCSM and MWTM are available in adhesive-coated configurations.
When heated according to the manufacturer's installation instructions, the internal hot-melt adhesive softens and flows to help seal the interface between the tubing and the underlying cable or connector. This helps protect electrical connections from moisture and environmental exposure.
The distinction is not simply that WCSM seals while MWTM does not. Both can provide sealing when the appropriate coated version is selected.
However, uncoated MWTM is intended for cable rejacketing applications rather than applications requiring the adhesive seal provided by coated tubing. Verify the exact product configuration before ordering.
For underground distribution systems, outdoor cable installations, and other environments where moisture intrusion is a concern, selecting the appropriate adhesive-coated product is particularly important.
Selecting heat shrink tubing for an electrical application requires more than choosing between heavy-wall and medium-wall construction.
Both WCSM and MWTM are used in low-voltage cable accessory applications. Their use in higher-voltage systems depends on the specific function being performed. For example, tubing used to restore a cable's outer jacket is performing a different function from tubing used as part of an electrical insulation system.
TE Connectivity identifies applications for these products that include sealing and rejacketing on certain medium-voltage cables. That does not mean every WCSM or MWTM part is approved for use as primary insulation at those voltages.
Before specifying a product, verify:
For medium-voltage utility work, follow the manufacturer's documentation and the requirements of the cable system or accessory design.
The best choice depends on the requirements of the specific installation.
Neither product is universally better. The correct selection depends on the cable dimensions, application, environment, and performance requirements.
WCSM and MWTM may be alternatives for certain cable sealing or rejacketing applications, but they should not automatically be treated as interchangeable.
Their wall thicknesses, shrink ratios, dimensions, and available configurations differ. An alternative must meet the requirements of the original application.
Before substituting one product for the other, compare:
A product that fits the cable physically may not provide the required performance for the application.
If you are replacing an existing Raychem part number, checking the manufacturer's product documentation is the best way to confirm compatibility.
Powertech Associates and Utility Power Supply Company support the electrical utility industry with products and solutions for cable installation, maintenance, repair, and distribution infrastructure.
Browse our online store for Raychem WCSM Heavy-Wall Heat Shrink Tubing and Raychem MWTM Medium-Wall Heat Shrink Tubing.
If you need help selecting the right tubing, start with the existing part number, cable diameter, application, and required tubing length. These details help narrow the available options and ensure that the selected product is appropriate for the intended installation.
For assistance identifying the correct part number or evaluating a potential substitute, contact Powertech Associates.
WCSM is heavy-wall heat shrink tubing, generally featuring a 4:1 shrink ratio. MWTM is medium-wall tubing, generally featuring a 3:1 shrink ratio. WCSM emphasizes heavier protection, while MWTM balances protection, insulation, and installation profile.
Yes. WCSM is classified as heavy-wall tubing, while MWTM is classified as medium-wall tubing. However, actual recovered wall thickness varies by product size, so compare the specifications of the individual part numbers.
Yes. MWTM is available in adhesive-coated configurations, as well as uncoated configurations for suitable applications. Check the part number and product documentation to confirm which version you need.
WCSM can be used for specified sealing and cable jacket restoration applications on cables up to 35 kV. This does not mean that every WCSM product is suitable for primary insulation at 35 kV. Confirm suitability for the exact cable and application with the manufacturer's documentation.
Certain MWTM configurations are suitable for sealing and rejacketing compatible cables up to 35 kV. The tubing's suitability depends on its intended function and the specific installation. Do not assume that MWTM provides primary medium-voltage insulation.
WCSM generally has a 4:1 shrink ratio, compared with approximately 3:1 for MWTM. This gives WCSM a wider diameter range, although the actual dimensions must still be checked.
Start with the cable's outside diameter, the largest connector diameter, the required finished length, and whether adhesive sealing is needed. Then verify the product's dimensional range and approved application against TE Connectivity's technical documentation.
