You also need to look at the insulation requirements. A voltage may be very=
 low
but may still be dangerous because it is connected in an unsafe way to main=
s
voltage. The insulation barrier between mains and the low voltage could the=
n
break down because of a short overvoltage surge on the mains.

This is all well regulated in safety standards for consumer products. Not s=
o
for DIY:ers.

/Ruben


> What kills is current through heart muscle locking muscle and preventing
> heart action. Removal may or may not still kill - if heart fibrillates
> (noisy electrical chaotic shimmer mode) rather than restarts you 'have
> problems'.
>=20
> A  <=3D 30VDC power supply will generally be safe. It's best to avoid con=
tact
> if possible, NOT work in damp conditions and not have a situation where i=
t
> can ever be applied across your chest. eg carrying a 24V lead acid batter=
y
> of any size with contacts against your chest or against a shirt if you ar=
e
> sweaty COULD be fatal but is unlikely to be.
>=20
> 1. Rub your chest with saline solution and apply two 30V electrodes to sk=
in
> across heart or nearby and it has a good chance of killing you.
> 12VDC applioed via electrodes across a (convict) volunteers chest has
> resulted in death. This was unexpected and in spite of resuscitation
> attempts.
>=20
> 2. Stand in salt water with bare feet with one 30V terminal in water also
> and brush other terminal with dry hand and you will PROBABLY not feel it.
>=20
> 3. Not many people know the following. I have a friend who experienced th=
is
> with 12V while flounder fishing with a pole lamp with a metal pole. An
> unexpected lockup experience.
> As in 2. above but add saline to hand that grasps and grasp terminal so
> there is hand - foot conduction and you may get muscle lockup in hand so
> you cannot let go. This MAY kill you but that is very unlikely (providing
> somebody unlocks your hand so you can wander off.
>=20
> 4. Generally under almost any circumstance you would normally meet you'd
> not feel 30V or have adverse reactions BUT as above there can be exceptio=
ns.
> I'd regard 12V and below as essentially super safe, 24V as safe with a
> soupcon of care and 30V as hardly worse.
>=20
> Work on a Telco wiring frame with 50V and no care is usually taken to not
> make contact and no feelings of electricity present when you brush
> contacts. BUT on a high humidity day you start to get annoying tingles
> across the nuckles.
>=20
> 100 VDC will happily kill you in many cases BUT may not. I'd not grab two
> 100V terminals for any reason that comes to mind.
>=20
> AC is generally safer than DC at any given voltage as your muscle
> cyclically relax allowing release.
> I have had perhaps dozens of 230 VAC shocks of various magnitude.
> Plus a very few at 1000+ VDC
> I try to avoid all such these days and have not had a decent shock for so=
me
> decades AFAIR. (A good shock across the head aka ECT may clear short term
> memory, so one can never be sure :-) ).
>=20
>=20
>=20
>=20
>   Russell
>=20


=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=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
www.liros.se
Tel +46 40142078
=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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.