High Places Phenomenon (HPP), or more commonly, "l'appel du vide," (the call of the void) is the sudden, inexplicable urge to jump from a high place, even when you have no intention of harming yourself.
I've never heard that call: never felt that urge. But my wife has. She isn't scared of heights. She'll happily climb to the top of an enclosed rooftop terrace.
But without that balustrade, she'd surely have felt the urge to sprint towards the edge and hurl herself off. She does not however, unless you're inclined towards Freudian psychology, have a secret death wish. It is more commonly understood that l'appel du vide is a cognitive glitch; a misreading of the self-preserving signal to back away from the edge. A bit like misreading the red stop light as a signal to go. Perhaps, not unsurprisingly, it's experienced as an unpleasant feeling of uncanniness. A feeling better avoided than overcome.
From Heights to Hazards: Expanding the Concept
Callum Robinson, in ‘A Brief Note On: Health and Safety’ in his excellent book Ingrained, feels the urge from the top of a tree: the urge to. He gets it. That uncanny urge. But Robinson, a furniture maker and a wood worker, takes it a step further, imagining himself impulsively sprinting towards a bandsaw and then leaping to meet the blade head first.
He once made the mistake of assuming it was a universal feeling asking a colleague if they'd ever considered running into a cutting machine. Robinson conveys the awkward silence that follows so well that the reader feels the uncanniness of it all.
Andrew Klavan tells the story of a Romantic poet's fascination with electricity. At the the beginning of the nineteenth century, long before the invention of the Regs Book, the poet Percy Shelley would while away his college days at Oxford by collecting pieces of electrical equipment. He was fascinated by the subject. His friend T.J. Hogg would help him attach wires to his hands and body, and then shock him until 'his long, wild locks bristled and stood on end'.
Like Shelley, I wanted to know what an electric shock felt like. I imagine most, if not all first year apprentice electricians, wonder what it feels like. An old lecturer advised me that there were only two possible outcomes: you'll either still be alive, or you won't. A nice, straightforward binary outcome. After I found out, I stopped wondering. I've never felt the urge to put my hands on three-phase busbars out of curiosity. It's not fear; it's just respect for the amoral phenomenon of electricity. Perhaps it was this amorality that appealed to Shelley.
Robinson's piece prompted some questions about accidents in the workplace. Was it possible, I wondered, whether those individuals who hear l'appel du vide were more likely to have accidents because they inadvertently listened too closely to the call? Think of that French verb, S'appeler, to name oneself. Are accidents an identification with the void, as if the void knows your name?
Etymologically inaccurate as that reading is, it's possibly also the wrong way around. What if sufferers of l'appel du vide aren't more prone to throwing themselves from high places but less likely to do so precisely because they're experiencing an urge without an attendant desire? Someone who experiences l'appel du vide is actually receiving a very strong safety alert from their brain. They are keenly aware of the danger. The feeling is unsettling, but it serves as a powerful reminder of the "void" and the need for caution.
What if it's people like me, people who don't get it, who are oblivious to the danger who are more likely to injure themselves? Someone who doesn't experience the call might lack this specific, visceral safety alert and therefore might not have the same immediate, physical sense of danger that the "call" provides. This could make me more susceptible to accidents because I might not fully register the presence of the void and the risks associated with it. The silence leading to a false sense of security.
But it's not just Robinson fils. Robinson père too. He even has a name for it: "Machine Tool Vertigo". And with just that word it's impossible not to have Bernard Hermann’s chords sound in your head. And although l'appel du vide isn't acrophobia it's equally impossible not to picture James Stewart on the very edge of the mission's bell tower.
P Company
"P Company," is a gruelling 5-day selection course for the British Army's Parachute Regiment. It's a physically and mentally demanding test designed to identify individuals with the required grit and resilience to become airborne warriors. Passing 'P Company' earns you the right to wear the red beret. As a case study, it helps illuminate some possible answers to those questions.
The Trainasium, a core component of P Company selection, is an elevated assault course set at 30 to 60 feet above the ground. The most challenging part, the "shuffle bars", involves walking across two parallel scaffolding poles. This scenario is a deliberate test of a soldier's ability to function under the physiological and psychological stress that this height and lack of a protective barrier creates.
The shuffle bars are actually not that high off the upper platform. But because the whole trainasium structure takes you above the treetops, standing on the bars is designed to make it feel a great deal higher than it is. It's a clever psychological trick: make the candidate feel fear without putting them in any real danger.
One other feature of the shuffle bars which makes them scarier than they actually are, is the absence of any barriers. One could, you're made to feel, fall a great distance. But P Company isn't designed to identify people who aren't scared. Instead its designed to identify those recruits who can still perform effectively under fear's influence. Not to not hear the call of the void, but to hear it, and still do your duty.
Physical and Metaphysical Barriers: The Urge Without a Desire
When my wife and I climbed out onto the roof terrace of The Music Room, the balustrade acted as a physical barrier. To answer the call she'd have to do something more than just run and jump . She would have to climb over the barrier and that's not what l'appel du vide prompts.
But more significantly, she didn't hear l'appel du vide. That was odd to learn. At a tautologically obvious level, physical barriers act as physical barriers but they also act as a sound barrier blocking off, or silencing, the call of the void. And so, on another level, since there is no objective call to hear, they also act as a psychological barrier. There was no immediate sense of danger and therefore no signal to misread.
Conclusion
Barriers in a distribution board are crucial for safety. They are designed to enclose or shield live parts, providing a physical barrier that primarily prevents accidental contact with live electrical parts. These barriers typically offer at least IPXXB or IP2X protection, meaning they prevent access by small objects like fingers.
But, remember, next time you fit one: it's not just a physical barrier; you're silencing l'appel du vide.
Sources & Credits
Robinson, C. (2024) Ingrained: The Making of a Craftsman, London, Penguin
The Institute of Engineering and Technology, (2022) BS 7671 2018 + A2, Requirements for Electrical Installations, Eighteenth Edition, London, IET
Klavan, A. (2022) The Truth and Beauty: How the Lives and Works of England's Greatest Poet's Point the Way to a Deeper Understanding of the Words of Jesus, Michigan, Zondervan Books, (quoted from pp.72-73)
Image Credits
Bruce Robinson in The Pirn Inn as part of Balfron Book Festival, 6th September 2025. Photo taken by Donna Nicholson-Arnott
A Rooftop Terrace With A View, (2nd August 2025) taken at the Landmark Trust's Music Room in Lancaster. Photo taken by Donna Nicholson-Arnott
Trainasium, The Parachute Regiment Training Company, (17 April 2019), X, https://x.com/Para_Training/status/1118585166467932161, (retrieved 19th September 2025)
File:Shelley Memorial, University College, Oxford (5178754841).jpg, Wikimedia Commons, https://share.google/cOQU4iUTDhwstb3aJ, CC 2.0, (retrieved 19th September 2025)
