It's about 60v once an arc is established and is almost independant of arc length (10v at each contact and 40v across the plasma) It's the air being ionised. Lee. ---------------------------------------------------------------------------- ---- This email is intended only for the above named addressee(s). The information contained in this email may contain information which is confidential. The views expressed in this email are personal to the sender and do not in any way reflect the views of the company. If you have received this email and you are not a named addressee please delete it from your system and contact Merlin Communications International IT Department on +44 20 7344 5888. ________________________________________________________________________ This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________