Also its worth doing some MPE calculations for your rig
again just to show any EHO or even some venues have thier own safety officer who tend to start asking akward questions
most of the time they look at the calcs shrug thier sholders and walk away ( but at least they know you have done your homework )

the HSE book shows you how to do this ( and it looks very complicated )

but james stuart of Laservisuals has written some damn good software that does the job for you

see it here http://www.laservisuals.com/sglite.php

the lite version is free, if you register ( i think sometimes registration does not always work ) if not send him an email
the pro version is really for the big display companies but it is amazing

Hope this helps .... All the best ... KARL