Do you think it’s best to use pre-heat shrunk crimp connectors or bare connectors with shrink sleeves added during the install?
A: The key thing with making a nice job of butt connections, no matter how they are shrunk, is to ensure connectors are the right gauge to carry the wire and to ensure the heat shrink tubing pieces are long enough to cover your stripped wire ends. If you get too enthusiastic with stripping, make sure you trim the wire ends to ensure naked conductors are not hanging half an inch out of the butt connector. You can certainly add a heat shrink tube over a butt connector that already has heat shrink pre-applied. A squirt of silicone spray will make sliding the tube over the connector easier, or you can use over-size tubing.
When heat shrinking, start at one end with the gun and work your way along and around the tube until you have complete coverage of the underlying connector with no air pockets and no looseness around the cable insulation. Use a corded heat gun wherever possible – they cost next to nothing, are safe when properly handled and will give a clean, even shrink. Heat shrinking is great for protecting connections from corrosion and strain. A good shrunk connection can only be removed by cutting it out of the cable – it will be more robust than the run.
Something else to bear in mind when building strong butt connections is to use a dedicated butt connector crimper. Sure, you can use a crimper/stripper but it’s never going to do as good a job as a dedicated butt crimper with a tab locator and functionality in the jaws of the tool. Just getting a crimper/stripper into position if you’re using a gauge located way out near the tip can be a major pain – you may also need to use excessive force to close the crimp. Dedicated crimpers make the process so much easier, especially in the tight and hard to reach places that typify electronic security applications.