Martin writes:

...snip snip ...
>         I have a pic design which uses nitinol wire as actuators for an
> art/robotics piece.  Esthetics dictate (actually the designer dictates)
> that the wire be exposed externally so that it is visible.  My concern is
> that the wire will driven by 50 volts at 60 Hz from the secondary of an
> isolated step-down transformer.
>         So here is the concern.  There is plenty
> of current available from this transformer secondary.  Is 50 volts enough
> to give a jolt to the happy art viewers if they happen to touch
> it?  The transformer manufacturer said that one cannot feel less
> than 70 volts ac.  Between wires they could touch the power.  I am concerned
> that no one get an unpleasant shock and that the artist and I do not get sued.
> Do any of you know what type of liability we might have here?
...snip snip ...

Some time ago I recall learning that 40V was the safety margin. In
fact, it all depends on skin dampness, current paths, etc... I
personally would almost always get a shock from a 50V source, but hey,
I wouldn't go as far as suing you for that :-)

Maybe a warning sticker will help too?