DIYbanter - View Single Post

Spurious Response

On Mon, 02 Jul 2007 07:21:32 -0700, wrote:

On 2 Jul, 02:36, "James Sweet" wrote:
"Gary Tait" wrote in message
4...
wrote in news:1183330881.790940.287160
@n2g2000hse.googlegroups.com:

Are you really saying no-one ever unplugs things withoutout turning
them off first? I really doubt it.

Some equipment simply has no off switch..

Who cares? I unplug and plug in items that are turned on all the time, worst
case you get a little spark, it doesn't cause any problems. It's not hot
enough to pit the plug prongs or contacts.

Its well known that repeated small sparks make a total mess of the
contact surface. This was one of the problems of our olf round pin
system half a century ago.

It is also well known that the properly designed flat blade has a nose
which has sharp enough corners to be the spark point for any arcs. That
means they will all begin or end along those edges, and along the "lead
in" faces of the receptacle. This means that the swept surfaces that
make up the "contact area" of the blades and socket terminals during use
will always be in fine shape.

Our plugs are designed to handle tens of thousands of "hot insertions"
like this. It has to handle some specific number at full rated current
as well. It is part of the design spec for the outlet. This is also why
the ground pin on 3 wire setups is slightly longer. It "makes" contact
before the other "pins" (blades).