Andrew wrote:

Mike Clarke wrote:

They don't appear to depend on the plastic to maintain the pressure on
the joint. Even if you strip away the plastic housing it looks like
the springy metal would still hold the cable ends securely together.

But does the springy metal rely on the integrity of the
plastic housing to maintain its pressure on the cables ?.

Even after the plastic housing has caught fire and completely burnt
away, the springy metal still connects the wires ...

https://youtu.be/2uYD8e7idnY