No subject

looking for this data to refute the need for an isolation transformer
and good grounding. I am not, I was just wondering if there were any
statistics on this issue.

A neighbor down the road was killed (electrocuted) while using his
supposedly double insulated hand saw plugged into an outdoor GFI through
a 50 foot outdoor extension cord, while he was standing on his dry dirt
driveway cutting wood on a saw horse. The investigation on how that
happened is still going on. 

No matter how careful you are, it can still bite you.

73, Ray  W2EC


Barry Hauser wrote:
> 
> On Wed, 13 Feb 2002 13:06:18 -0800 k6uuz at juno.com (Ed Richards) writes:
> > Another safety precaution is to use a 3-wire cord and plug. Connect
> > the safety ground (green) wire to the outside case and the neutral
> > (white) wire to the chassis. (double protection) and the hot (black)
> wire to
> > the switch. Sometimes this requires a small change to the wiring of the
> > switch. This keeps the cabinet and the chassis grounded all the time
> > and when turned "off" the entire radio is grounded except for one
> > terminal on the switch.
> 
> Hi Ed & list:
> 
> Gee -- I didn't think tying the neutral and ground together (potentially)
> was OK.  Any other opinions on this?
> 
> As for Ray's query (Hi Ray), I suspect meaningful stats on AC/DC radio
> fatalities may be hard to find.  Then there's the key marketing question
> of how low a body count is acceptable per 100,000 units sold -- y'know,
> "collateral damage".
> 
> Aside from outright burns and fatal electrocution, the other problem is
> what else happens when you get a shock.  You learn just how high or far
> you can jump.  Sometimes it's the physical injury that results from
> explosive reflex action that manifests the damage.  On top of all that,
> if you were holding the radio or had your hand on it, it could get
> damaged.
> 
> Many radios and both old and new appliances can present such a risk.  For
> example, the old Echophones have hot chassis attached to the cabinets
> with insulated washers -- which could have been left out duriing
> reassembly, or deteriorated and crushed, etc.  Many old plastic/bakelite
> table radios depend on plastic all around, including the knobs for
> protection.  However, the chassis mounting screws that are exposed at the
> bottom are potentially live.  Many are pretty safe closed up with cabinet
> intact, but battery radios have pop open hatches -- like the
> Transoceanics -- which expose the live chassis.  There's no interlock as
> with TV sets..
> 
> Another (though somewhat less safe) approach is to replace the line cord
> with at least a polarized two-prong version.  The hot side should be the
> switched side, not the chassis side, and that may call for some minor
> rewiring.  Of course, this relies totally on correct outlet polarity.
> Lately though, nearly every appliance comes with a polarized two prong
> plug -- even table lamps.  And, they have a warning label on the line
> cord about not defeating the polarized plug and making sure outlets are
> correctly wired.  Other appliances warn about replacing knobs, loose or
> missing parts, etc.  So it would seem, the "issue" is not limited to 50
> year old AC/DC radios.
> 
> I don't know that it's realistic to hope that all hot chassis (and hot
> cabinet) radios will be retrofitted with isolation transformers, but
> maybe a practice should be started of attaching a label to the line cord
> with a standard warning -- admittedly lame by comparison, but better than
> nothing.  If the unit has not yet been fitted with a polarized or
> grounded plug, the old plug can be marked as to which side goes to the
> hot, or small slot. Of course, the warnings on the new appliances are
> intended more for liability control than actual accident prevention.
> Again, it has to do with acceptable levels of collateral damage.
> 
> If you don't want to put isolation transformers in all your hot chassis
> radios, you can get a high current isolation transformer -- e.g 10 amps,
> and use an outlet strip for several of the units at once.  Of course,
> that doesn't protect some future owner.
> 
> Sorry for the lack of brevity, but one more curious thing.  One modern
> day equivalent of the hot chassis "solution" is the wall wart.  Notice
> how many things have them, in addition to portable, and not so portable
> radios?  This takes the AC out of the chassis and cabinet altogether --
> so, among other things the appliance itself doesn't have to be hi-pot
> tested and UL or CSA listed.  Of course, the vast majority of wall warts
> never power off (primaries connected 24/7) and were sited by our
> President as being "power vampires" slowly sucking out megawatt-hours by
> the milliwatt.  Not to mention -- did you ever see one with a fuse?  I
> wonder what the stats are on those -- where they burn before tripping a
> breaker?
> 
> Barry
> Always with one hand in a pocket, and, uh, the other hand in the other
> pocket.
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