On Thu, 31 Jul 2008 09:18:02 +0100, "Arfa Daily"
put finger to keyboard and composed:


"Brian Sandle" wrote in message
...
An old Hitachi electric drill as part of a set with many attachments had a
wrongly wired plug.

This is in New Zealand where the phase is the slanting pin socket on the
left. The sealed Hitachi plug attached to this faulty drill had the red
wire connected to the right hand pin as it is pushed in.

(Fault was less than tight brush scews)



As far as I've always understood it, 'polarity' on two-wire double insulated
equipment, is more a matter of convention than safety, from a punter point
of view. Not quite the same for the service engineer who has to get inside
the equipment, where he will quite reasonably expect any power line fuses,
or single pole switches, to be in the live (phase) wire, rather than the
neutral.

I'm seeing a lot of this kind of PSU wiring in DVD players these days:
http://www.users.on.net/~fzabkar/DVD...Photos/PSU.jpg

One 2-pin plug connects to the mains, the other to a single pole power
switch. By interchanging the plugs you can either switch and fuse the
active lead, or switch and fuse the neutral lead. If you switch the
active lead, then the case potential drops to 0V. If you switch the
neutral, then the RF suppression caps elevate the case to full mains
potential, albeit harmlessly. However, the resultant tingle can cause
some consternation among consumers, and consequently some PR problems
for manufacturers.

- Franc Zabkar
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