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RE: buzz buzz buzz - I wonder why it does?
- To: <ukha_d@xxxxxxx>
- Subject: RE: buzz buzz buzz - I wonder why it does?
- From: "Mark Harrison" <Mark.Harrison@xxxxxxx>
- Date: Sat, 20 Apr 2002 23:43:32 +0100
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Power
= Current * Voltage
Current = Voltage / Resistance
->
Power
= Voltage Squared / Resistance
The
thing that's fixed is the resistance your body provides... the things that
we
can change are the voltage supplied by the power source, and the resistance
of
the power tools.
Halving the voltage means that we have to make the power tools 4
times as
resistive. This is (marginally) less efficient.
Halving the voltage means that, if you get it applied to you while
another part of you is grounded, then you only get 1/4 of the joules
converted
>from
by a reasonable amount.
Regards,
Mark
Keith
I
thought it was current that killed, not voltage? Static electricity
produces very high voltages.
W=AV, so lowering voltage increases current to provide the same
power to a the tool.
What
am I missing in this argument?
Nick
Yes.
All electrical equipment used on building sites should be 115V
maximum under Health and Safety regulations.
They even use different colour cable to differentiate
voltages
Yellow = 110V
Blue = 240V
Red = 415V
Even things like Working Lamps are operated at
110V. Its a very sensible idea when all that water is about. Compared to
using something directly powered from the mains ( 55V vs 230V ) any
shock you might receive will be a quarter of what it would have been
therefore a quarter of the current therefore you will almost cetainly live
to go to work the next day.
Keith
www.diyha.co.uk
www.kat5.tv
> A site transformer is an
isolation transformer designed for use on a
> building SITE (guess
where the name comes from!)
> Because of the often wet environment
the output is centre tapped and
> tied to ground. This limits the
maximum voltage to earth to half of
> the output voltage. Most
shocks are from a single conductor to earth
> so this is an extra
safety feature
So do they expect everyone working on these sites to
have special 115
volt tools for the job? Or does this only apply to
designated high power
devices that are more prone to "Accidents" then a
normal power tool?
For more information: http://www.automatedhome.co.uk
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