In article , Dave Plowman (News)
writes

I've known quite a few small value ceramic capacitors fail short circuit -
but on low voltage DC circuits. Do they use some special type that
positively can't do this?

Yes, you can get safety rated capacitors for this job:

Class X capacitors are safe to use between line and neutral where
failure would not expose the user to a shock but where a fault would
need to be cleared in a safe manner.

and

Class Y capacitors are safe to use between line and earth or other
positions[1] where failure could expose the user to a shock.

[1] eg across a double insulated (or reinforced insulation) barrier such
as between input and output of an unearthed (class 2) switched mode
power supply, as discussed on this thread.

Commonly available as metal film or ceramic, ceramic better for HF
suppression due to their construction.

Class X:
http://cpc.farnell.com/CA06046

Class X/Y (dual purpose):
http://cpc.farnell.com/CA06001
--
fred
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