Can Heat Shrink Splice Kits be used in underground applications?

Yes!

Boshart’s Clear or Black Adhesive Lined Heat Shrink Tubing can and has been used for direct burial application as there are no flammability issues with a buried connection. Black tubing is flame retardant and should be used to make splices in all above ground electrical cable splicing applications.

The use of “Heavy Duty” Thicker Wall tubing with a 3:1 shrink ratio for additional abrasion resistance (HS Series Splice Kits) is the best option and suggested over the “Fast Recovery” tubing that has a 4:1 shrink ratio (Boshart HSK and HSKC Series) which has a slightly thinner recovered wall thickness.

However, either option is suitable. Both products will make an excellent moisture-proof seal so there are absolutely no issues with using either. Although, if abrasion resistance is a concern the installer may want to add an additional 2-3 layers of 8 mm electrical tape (part number ETCWNL) to cover the splice connections for peace of mind, but this is optional.

NOTE: If proper care is taken during the back filling process, with a sand pack to protect against falling rocks, the added protection may not be required. However, the added protection is always best practice, regardless of whether 3:1 or 4:1 ratio shrink tubing is selected.

IMPORTANT: It is vital that you verify that the wire used is manufactured with insulation which is approved for underground / direct burial applications. Certain wire types must be installed in an approved electrical conduit. In addition, one must pay attention to minimum bury depths which may vary from one district to the next.

CAUTION: The installation must always be in compliance with all applicable national and local electrical codes for the area where the installation is made. If in doubt it is best to reach out to your local electrical inspector. The AHJ (Authority Having Jurisdiction) responsible for the project and enforcing codes, standards, and regulations related to construction and safety, always has the final say on a product or materials suitability.

Additional Resources:

https://support.boshart.com/how-do-i-select-a-heat-shrink-splice-kit

https://support.boshart.com/what-is-the-difference-between-31-and-41-shrink-ratios-on-your-heat-shrink-and-splice-kits

https://support.boshart.com/are-the-tubes-in-your-splice-kits-dual-wall-heat-shrinkable-tubing

https://support.boshart.com/what-can-i-use-to-shrink-down-my-heat-shrink-tubing

https://support.boshart.com/glossary-of-heat-shrink-tubing-terminology