Does anyone know if the new Yongnuo RF603 C3 Transcievers have a safe sync voltage for use directly on a Canon hotshoe? Been searching but I cannot find any useful data for the sync voltage.

Triggers always have low voltages. It's old strobes that expose the camera to possibly hazardous voltages.

You're safe

<Chas>

Thanks Chas,
Was concerned about 'fry' status.

You needn't have worried. There's nothing in a trigger that generates high-voltages. Only stobes have HV to fire the tube.

<Chas>

Be careful of using high voltage flashes, I ruined 2 602's with an old flash...
pretty lame

You may take a look on this chart
http://www.flickr.com/photos/image_melbourne/5590340051/