28 Aug
2012
28 Aug
'12
12:28 p.m.
Paul Anderson wrote:
Of course wall-warts are country specfic in that the mains voltage and
conenctor are different in differnet countries. So I've probably never
seen a modern one intended for use in the USA and thus UL listed
But the ones we get over here have no protective devices at all. No fuse,
no thermal fuse. If you are lucky, the resistors in a swithc-mode wall
wart are fusible, flameproof types. Most of the time they are not.
For linear wall-warts, the transformer primary is _supposed_ to burn out
in a safe manner if the thing is overloaded. My (accindental) experience
is that they do not. The transformer can get hot enough to soften the
plastic case, but it does not burn out.
I can understand why people go for them. It's
a convenient, commonly
available supply, and by using it you can eschew the expense of UL/CSA
testing. What we really need, IMO, is to accept that a large quantity of
On 08/27/2012 12:28 PM, Tony Duell wrote:
This indicates to me that the whole apporval
process is broken (it is
over here too). Most wall-warts are not that safe (they do not have
proper fusing or other protective decvices, they do not necessrily fail i
n safe way).
The wall warts don't pass UL if they don't have appropriate fusing or
protective devices. The ones you're talking about that don't have fusing or protective devices either aren't
actually UL listed, or the
manufacturer changed the design without resubmitting it, in which case
the listing is void and the manufacturer is potentially liable for a
considerable amount of damages.
That may well be true. It doesn't mean I consider said units to be
remotely safe. Unlike my home-made PSUYs where I tend to put at least a
fuse in both pirmary and secodnary circuits.
-tony