Philco 42-380 safety cap

[exray]

The name "safety cap" is misleading. Actually only one vendor I know of uses that term but it has entered the lexicon.

It doesn't add any safety to the user per se. The safe aspect is like Ron describes, means that it fails open and is flameproof. If you're familiar with some of the older AC bypass caps like the bumblebee types they had a nasty habit of overheating and exploding - sometimes spraying bits of foil all over the chassis.