Who's rewired their house for this hobby?

Pete Turnbull pete at dunnington.plus.com
Mon Nov 24 20:03:22 CST 2014

On 24/11/2014 08:52, Brent Hilpert wrote:
> Well, I'm willing to entertain counter-intuitive notions but I'm
> really not convinced. Some reading suggests going beyond the current
> level at which one loses intentional muscle control, while it will or
> can result in involuntary muscle contractions, those contractions may
> be more likely to result in hanging on rather than getting kicked
> off, and you're more likely to exceed that current level with the
> higher voltage. Getting 'thrown off' also has it's own set of
> associated risks.

I was just reporting what I read, which came from one of the members of 
the committee that made the decisions - after much "discussion", 
apparently.  To be honest, I doubt there's much difference, and 
certainly any voltage in those regions can be fatal.  In fact, much 
lower voltages can be fatal, if applied to broken skin such that current 
passes across (actually, through) your chest.  That's why there's such a 
category as SELV.  Yet I remember once getting a very painful shock from 
a 9V PP3 battery when a couple of terminals went through my skin, but 
fortunately only across one hand.

> But isn't there an internal logic problem in there to begin with? I
> thought the point of the step-down/isolation transformer for portable
> tools was to reduce the 240V to a safer level (or is just to make it
> easier for manufacturers, to only have to manufacture 110/120V tools
> worldwide?

Not really, the point is to reduce the maximum to *50V* above ground, 
which is below the 90V (?) "safe" threshold.

  in which case one would think the onus would be on NA to
> change). Those  transformers aren't required in NA because we're only
> operating at 120V. Once you require the transformers to get down from
> 240V, you might as well go to the center-tapped 55-0-55 technique at
> a small increase in complexity over 0-110 for a further safety
> improvement.

As the EU requires.


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