No wonder theatre gossip is full of stories - some apocryphal, admittedly, but some merely exaggerated - of ambitious artists devising daredevil ways to delight audiences, only for the safety police to enforce banal compromises. Have you heard the one about the Camden fire brigade forbidding a visiting German act from microwaving a chicken on stage? Or the production of Alan Bleasdale's On the Ledge, whose suicidal hero spent the play teetering from a building to which he was visibly harnessed?

Then there's the experience of Kneehigh Theatre. Last year, Hammersmith Council told the company that a sequence in its production of Euripides' The Bacchae, in which one performer dramatically scales the back wall of the set, could not be performed without a hard hat. "The set was a bespoke design for this actor and her abilities," says director Emma Rice. "We'd done everything correctly, we'd put in all the safety reports. And yet, here was someone with a clipboard telling me the show could be closed. I was furious." Compounding the fury was the inconsistency of the decision. The routine had been approved at West Yorkshire Playhouse and various other venues across Britain.

National guidelines can be subject to wide degrees of interpretation at local authority level, Liner admits. Now, though, such matters are being taken out of local authority hands. The new Licensing Act and forthcoming legislation on corporate manslaughter look likely to return responsibility to the theatres themselves. Which may or may not be a good thing, says David Adams, safety expert at the Association of British Theatre Technicians. "It all comes down to the balance between how much you want to make your own decisions based on experience, and how much you want absolute instructions."

Adams claims to have spent "most of my life persuading licensing authorities to risk-assess, rather than just saying: 'It's got to be 3ft thick otherwise I'll ban it.' Because those absolute rules relate to general industrial environments rather than the peculiarities of theatre. In theatre, we're always using things for the wrong purpose and not how the manufacturer intended. 'Is it all right to paint the walls with milk?' That kind of thing."

Often, there is no precedent for the unusual safety considerations that theatre throws up. And, Adams points out, theatre is even harder to regulate because it is full of people who are willing to take risks. "The 'show must go on' belief," he says, "is in direct conflict with safe working."

To some, though, restrictive safety rules are not so much an industrial as a cultural issue. Mike Roberts runs pyrotechnic specialists the World Famous, co-creators with Improbable Theatre of the firework-and-Sellotape spectacular Sticky four years ago. Roberts recently premiered a new show, Crackers?, which broached modern attitudes to risk and danger. The audience was offered a choice between safe and less safe areas in which to stand. "Do I want this to be a cosy and comfortable experience," they were invited to ask themselves, "or do I want to have a brilliant time?"

Roberts contrasts fireworks culture in Europe with the safety-obsessed domestic scene. "In Spain, you go to a firework show and people have wet cloths on their heads because they know that when you throw fireworks up in the air, they come down again. Here, people go to a firework show and expect it to be the same as sitting at home watching the telly." In the run-up to Crackers?, Brighton's health and safety people threatened to forbid hand-held sparklers being distributed to the crowd. "Which kind of says it all," says Roberts. "We have this passivity that's inspired by a TV-based culture. Life isn't about going outside and engaging with something, it's about sitting at home and consuming. We just wanted people to accept that risk is what makes life exciting."

Richard Wiseman would heartily concur. His initial plan for the show was to invite an audience member into the electric cage. "That idea lasted about 30 seconds," says Soho Theatre's no-nonsense production manager, Nick Ferguson. Even so, the very worst case scenario for the show, says Wiseman, is that: "The lightning strikes out and hits a member of the audience. That would technically be known as very bad. It's not a great ending: 'Thanks for coming along, and step over him on the way out.' "

Of course, rigorous risk-assessments have been performed. The electrical effect is being produced by a company called HVFX, whose work is more often staged in nightclubs or for television. To render the effect safe in an intimate studio, exceptional measures have been devised in collaboration with Westminster Council. There is a two metre exclusion zone around the stage. Wearers of pacemakers will not be admitted into the theatre. Nor will laptops, because, says Wiseman, "anyone in the front three rows wouldn't have a hard disk left. The field would wipe it straight away."

Worryingly, though, the show cannot be usefully rehearsed, because "the atmospherics change completely when you get 90 people in a room". Pending a demonstration in the actual environment, Westminster withheld the licence until the first day of performance. Meanwhile, HVFX have negotiated £12m worth of insurance, which means, says Wiseman, "that if they get sued, they're covered for a couple of deaths".

That news hardly puts a spring in my step when entering Soho Theatre on opening night, desperately seeking a sheltered back-row seat. But on its debut performance, the experiment is a resounding success. Wiseman and co-star Simon Singh are visibly nervous as two 3ft-high Tessler coils ("The coils of death!") are wheeled into position. A man in a boiler suit marked "HVFX Crew" scurries around scarily. A switch is flicked, and electricity arcs between the coils in spidery violet sparks. Fifteen seconds later, Wiseman, entombed in his chicken-wire sarcophagus, has survived. "The theory," he gloats, blinking back to life, "was right."

Is it exciting? Of course. "If it goes wrong," Wiseman says, "it's the worst day of your life." But when it goes right - well, great risks bring great rewards. And seeing death defied can be the greatest reward of all. "We live in a society where scientists keep getting asked about things," says Wiseman. "Is it 100% safe to eat beef? Well, even lying in bed isn't 100% safe. But we are so terrified of any risk at all. We want to be told that things are safe, but it's not 100% safe to do anything."