What is the name of the fabric sleeve insulator used for components (typically fuses) and solder joints found inside motor windings?

Can regular heat shrink tubing be used as a substitute?

enter image description here
Image by cwbenz. Retrieved from here.

  • \$\begingroup\$ maybe fiberglass and resin \$\endgroup\$
    – jsotola
    Dec 12, 2018 at 7:52
  • \$\begingroup\$ Heatshrink may degrade at lower temperatures than that stuff. \$\endgroup\$
    – user16324
    Dec 12, 2018 at 8:26

1 Answer 1


This is called sleeving. In this case it looks like uncoated NOMEX, but the specific brand might vary.
This is applied in electromotors and generators where this fiberglass-like sleeving is impregnated with insulating lacquer or resin during dip-sealing or vacuum impregnation.

This material is used because it can handle high temperatures and is not flammable. It also has a much higher kV/mm than regular heat shrink.

In fact, heat-shrink degrades rather quickly, and can becomes actually conductive, and is typically avoided when long term insulation is required. Hence why heat-shrink is more a low voltage repair material.

If you are not going to use lacquer or impregnation I suggest you look for coated fiberglass sleeve. This is coated with polyurethane or acrylic. A brand name of this could be Vidaflex.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.