On the picture from this question, what is the translucent insulation on the transformer center-tap made from? It looks like polyethylene, but it obviously isn't because PE would melt at soldering temperatures.
Electronic – this translucent heat-resistant insulation
identificationinsulation
Related Solutions
If you do the mechanical part of your job right, then there's no way that anything can be flopping around inside your box, just inviting disaster.
Here are a couple of examples of equipment laid out properly:
Notice how everything is laid out neatly, as if it were planned, and harnessed and secured properly in order to completely eliminate the possibility of an inadvertent mis-connection/short in the box.
Also, in the topmost photo, notice the use of crimp terminals and a Jones-type barrier strip secured to the chassis in order to make connections to a cable leading to the outside world, and a terminal board used to secure - and provide connections to - the resistor array.
This method of construction can be used universally where wiring by hand is required, will yield very reliable equipment, and eliminates the need for hot glue. ;)
It's just an established name, like the "duck tape" (which presumably is neither made out of ducks, not made for taping ducks) or "panzer tape" (which may or may not be used to fix tanks) or ... - the meaning of a thing does not always get reflected in the name, perfectly.
You can use it for lots of things (except insulating relevant amounts of voltage), and it is very useful for insulating things like 5V/3.3V circuits.
Best Answer
That looks very much like PTFE tubing. The thin-walled tubing tends to be translucent, but the degree of translucency also varies by manufacturer and even batch.
PTFE can operate up to 260°C continuously. Transformer tails like this are typically tinned onto the bobbin pins by solder-pot dipping, we use 255°C for our lead-free solder pots and the sleeving does not directly touch molten solder which leaves enough margin. As well as soldering you have to also remember that the maximum internal temperature of these type of high-frequency transformers can exceed 100°C which will limit your sleeving material choice too.