Certain tasks should never be randomly assigned.
If you have a pyrotechnical device, never leave the arming key in the firing system if you have to walk away from it… NO EXCEPTIONS. And yes, you have an arming key, the removal of which will make the effect impossible to trigger. Of course you do.
And of course, the only person with the arming key is the pyro effects person. Don’t just hand it to someone.
(thanks to Brian Oberquell!)