Medical standards is mostly (always?) more stringent than industrial standa=
rds =

regarding allowed currents through a human body. One reason for this is tha=
t a =

patient may have an open wound and not have the protection normally offered=
 by =

the skin.

/Ruben

> Somewhat relevant to this discussion:
> =

> >From the Australian Standards (with some editing):
> *
> =

> APPLIED PART
> *
> =

> A part of the EQUIPMENT which in NORMAL USE:
> =

> - necessarily comes into physical contact with the PATIENT for the EQUIPM=
ENT to
> perform its function; or
> =

> - can be brought into contact with the PATIENT; or
> =

> - needs to be touched by the PATIENT.
> =

> *PATIENT LEAKAGE CURRENT*
> =

> Current flowing from the APPLIED PART via the PATIENT to earth or flowing
> from the PATIENT to earth originating from the unintended appearance
> of a voltage
> from an external source on the PATIENT.
> =

> *ALLOWABLE VALUES OF PATIENT LEAKAGE CURRENT*
> =

> - DC: 0.01mA (normal conditions), 0.05 mA (fault conditions)
> =

> - AC: 0.1 mA (normal conditions), 0.5 mA (fault Conditions)
> =

> *Transient currents occurring during the first 50 ms following a fault sh=
all be
> **disregarded.*
> =

> =

> 2009/7/6 Ruben J=F6nsson <ruben@pp.sbbs.se>
> =

> >
> > > >
> > > > Ohm's law works very well for most metals. It is not a very good mo=
del for
> > > > the human body. Sweat and grip pressure greatly change the amount of
> > > > current which will flow for a given voltage. I also greatly suspect=
 that,
> > > > as the voltage climbs, there is a nonlinear increase in the amount =
of
> > > > current due to electrochemical breakdown of the skin. Also, all bet=
s are
> > > > off once the skin is punctured because the internal body fluids are=
 MUCH
> > > > more conductive.
> > > >
> > > > Sean
> > >
> > > But it would still technically follow ohm's law since the resistance
> > > of your body would change?
> >
> > All currents flowing in a circuit follow ohm's law.
> >
> > However, as soon as the current is not a DC current and/or the load is =
not a
> > pure resistive value or changes with voltage, time, temperature or what=
ever it
> > becomes a bit more complex. To complicate matters even more, the load c=
an have
> > inductive or capacitive components which makes the current, voltage and
> > resistance (or rather resitance + reactance) to change when the frequen=
cy is
> > changed. The current actually also becomes out of phase with the voltag=
e.
> >
> > /Ruben
> >
> >
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> > Ruben J=F6nsson
> > AB Liros Electronic
> > Box 9124, 200 39 Malm=F6, Sweden
> > TEL INT +46 40142078
> > FAX INT +46 40947388
> > ruben@pp.sbbs.se
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> >
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
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> http://www.piclist.com PIC/SX FAQ & list archive
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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

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