Me and several other technicians I have worked with and professors from many different schools believe a harness is going to harm you in the long run if a tip occurs. I feel much more comfortable standing in the
basket (not on the rails) and if a tip occurs having the ability to jump and
roll out of the
basket. With a harness I feel your more likely to get caught under the
basket or trapped in the
basket causing more harm.
A proper fall protection
system in a lift utilizes a shock-absorbing
lanyard. This largely reduces the risk of a tip-over in the event some falls -- even dives from the
basket of a vertical-mast(w/ outriggers), scissor, or
boom lift.
Short of driving a lift off of the
edge of the
stage, the odds of a scissor tip-over otherwise are almost zero in a theater.
Even in a single-man, to be ejected from the
basket in a way that you could be crushed by a lift during a tip-over, you would have to be standing on the railings or something similarly very dangerous to prompt the accident in the first place.
As for being in more danger by being in the
basket when it crashes into the floor -- I am able to imagine only one exotic scenario where anyone is safer jumping from the lift than if they were to remain in the
basket; a work crew was using an
articulating boom lift near a lake, and the crew was required to wear both life preservers and fall-protection. Fall-protection if the lift falls over, and life-preservers if a worker falls into the water. However, wearing both of those makes it incredibly difficult to move around -- it's impractical. When
OSHA was called to give their input because the regulations seemed absurd for this particular case, the final conclusion was that the greatest risk was of the lift crashing into the lake, and should that happen, fall-protection would serve the purpose of mafia blocks, anchoring them to the lake floor and drowning them.
The
OSHA inspector reasoned that this was a unique case where two regulations collided and were counter-productive to the
safety of the workers; he only required that the workers wear life-preservers and that fall-protection could be waived in this case.
Unless you're focusing lights over a large body of water or next to a cliff, you'll not be in a position where you are in greater harm in the
basket than if you jump from the lift as it tips over.
That said -- it is not mandated by
OSHA that a scissor or vertical-mast lift operator wear a harness, but it will not put you in the way of harm should you choose to wear one. If you come into harm's way during a tip-over, it's because you were misusing your lift in the first place.
Your insurance provider or employer may have stricter policies though. I know of film studios where even just getting into a lift to drive it from one side of the room to another at ground-level without fall-protection, a
hard-hat, AND steel-toe boots will result in a suspension.
To elaborate on Derek's comment, the great thing about science is that it's true whether you believe it or not. Like a mother telling her 7-year old not to
play in the street -- whether the child understands why they shouldn't
play in the street or not does not change the fact that if that child does
play in the street, there's a pretty good chance they'll get hit by a car.
