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Science, Maths & Technology

Lightning strike diary

Updated Friday 2nd June 2006

It's electrifying! Adam Hart-Davis and the team are struck by lightning.

Adam at the National Grid Copyrighted image Icon Copyright: Production team

November 13th before noon
Today Adam is at the National Grid in Leatherhead, just outside London, to learn all about lightning. By the end of the day he will be dangled onto - and touch - a live 400,000 volt overhead line (the wires that carry our electricity). He will be simulating the work the brave men of the National Grid do when they maintain pylons (the correct term is 'towers') and overhead lines by being lowered from helicopters. Like sparrows on the lines they are safe as long as they don't make contact with the ground.

10.30
At the Grid's high voltage testing laboratories Adam finds out how the Grid protects itself from lightning and power surges. Power surges occur when substations re-direct power and simply switch systems on and off. The metal mushroom forests of equipment they use seem to have come from a 1960s vision of the future. But without them we wouldn't be able to guarantee a regular or safe supply of electricity. The most impressive is the 'impulse generator' which stores up a 2 million volt charge with which it can zap the equipment to be tested with a simulated power surge or lightning bolt.

Pylons - known here at the National Grid as 'towers' are very attractive to lightning so they have been designed to conduct it safely away from the overhead lines. But sometimes a lightning bolt can 'induce' a voltage from the grid itself which then zaps down the lines and risks hitting the first substation it comes to - in either direction. Transformers at the substation are full of oil and when this instantly heats up they make a very big bang.

A massive electrical discharge... Copyrighted image Icon Copyright: Used with permission 11am
Adam stands by the wire dangling from the impulse generator with ear plugs in and his fingers in his ears, just in case. A red light goes on in this benign Dalek, a warning buzzer goes off and Adam tenses up. Seconds later the metal plate on the floor is zapped with 2 million volts and Adam literally jumps into the air with shock - more psychological than electrical. It looks rather good slowed down on the video we took.

We are very lucky to have filmed the electricity bolt in this picture captured from video - the bolt is so fast it usually falls between the frames.

... and we capture a bolt of electricty Copyrighted image Icon Copyright: Used with permission 12 Noon
Adam tests out Jem's amazing lightning simulator which (as usual) he and Chris have only just built - a copper tube in which little polystyrene balls are whizzed about by a fan unit. Jem is a master of the 'grammar' of science - its underlying scientific principles. He is so confident in his theoretical knowledge that he can be sure that his designs will work once they are built.

Not for him the TV chef's technique of turning to the oven to pull out the perfectly baked cake which he or she 'made. No - Jem likes to keep us waiting as he mixes the correct ingredients for the 'recipe' for his 'cakes' (inventions) and then 'bakes' (gaffer tapes/welds/hammers/saws/) them together for us only seconds before they are to be filmed.

His confidence, however, never appears to be so wholeheartedly shared by his boss Paul Bader who looks nervous as Jem starts up the fan unit. But soon enough a bright spark (not Jem - an electrical one) jumps from the copper tube (the cloud) to a neutral wire (the Earth). Inside the copper tube thousands of polystyrene balls are now whizzing around simulating the movement of rain and hail in a cloud.

Jem explains that the little balls (rain and hail), by being whizzed against each other, are 'stripped' of their electrons. These stick to the surface of the copper tube. The tube accumulates a surplus of electrons which zaps towards the earth (in this case a neutrally charged copper wire) due to the voltage difference between the charged tube (the cloud) and the uncharged wire (Earth). I think I get all that - do you?

 
The science shack prepares for zapping Copyrighted image Icon Copyright: Production team

13th November after noon
2pm
The Science Shack - looking a little out of its depth in this futuristic forest of mushroom-shaped gizmos here at the National Grid - is being dressed not to kill. Chris and Marty are fixing what looks like copper plumbing to the roof - in an attempt to make a lightning conductor.

3.30 pm
The Shack is finally zapped by the National Grid's impulse generator. Chris' conductor saves Adam and the future of Science programming. Well, he would have done if Adam had actually risked sitting inside the shed. He chose, instead, to operate the zap button itself. Was there a thought in the back of Adam's mind, as he pressed the button, that the Shed might actually explode? Was that a manic grin we saw flicker across his face? Or was he expressing confidence in Chris' lightning conductor?

The picture shows that the electricity jumped from the bottom of the conductor to the floor without going down the earthed wire along the floor. That's because the zap is simply too much for the wire to bear and it 'spills over' by jumping to the floor. Carl Johnstone our National Grid high voltage testing expert likes, when it is relevant, to compare electricity to water. This time he excels himself: 'it's like when you flush the toilet. The water fills up the bowl because there is too much pressure'.

Faraday cage Copyrighted image Icon Copyright: Used with permission 4.30pm
Marty's prototype Faraday cage is tested. Adam will be putting himself in a Faraday suit - which acts like this cage - and being winched 15 metres up in the air to touch a charge of 400,000 volts, making sparks fly from his fingers. Without the suit he risks death.

It is comforting to know that with this high tech model Marty has tested Faraday's assertion (in 1836) that if you put yourself in a cage which is electrically charged, even if you touch the cage, you are safe. Faraday discovered there is zero electrical interference inside. This little model has two little polystyrene balls swinging from each hand, attached by a wire to a stove lighter. When the model is standing on top of the cage and the lighter is clicked the balls swing about, affected by the charge. When it's inside the balls don't move. What more proof does Adam want that he will survive?

6pm
Jack Blackett, Laboratory chief, makes comforting noises about Adam's protective suit, it is lined with wires and even covers his feet. He will be winched up by a crane to touch an electric charge of 400,000 volts. Adam is insulated from the crane by a glass fibre rod hanging from its hook. The rod is tested to hold two tons which Adam thinks will suffice.

We climb to the top of the workshop and look down on the intrepid presenter. Adam hates heights - but for Science Shack he is prepared to face vertigo AND 400,000 volts.

Adam slowly ascends. For the purposes of filming this has to be done several times. Adam has his eyes shut for most of the journey.

Adam suited and dangling Copyrighted image Icon Copyright: Used with permission As Adam reaches out to touch the charge he manages to summon up a grin, despite his nervousness. A great crackling sound accompanies the sparks and Adam feels his hair stand up on end. He is elated, electrified even, by the experience, but has decided not to get a job as a National Grid maintenance engineer. They do the same as he has just done but hanging off a helicopter.

 
Why you should never be on the phone during a storm Copyrighted image Icon Copyright: Production team

14th November before noon
Today Adam and the team are at Brighton University making more lightning in the High Voltage testing labs. By the end of the day Jem and Chris from the Science Shack team hope to have knocked up a proper Faraday Cage for Adam to step inside before being zapped with a million volts of electricity.

10am
Dr Peter Howson, who runs the Brighton High Voltage labs, shifts a lever, flicks a switch, presses a button and strikes a Silver Birch tree with thousands of volts - simulating a lightning bolt. The sap in the tree instantly boils, explosively, splitting the trunk. Earlier he showed us what happened to a piece of dry wood - virtually nothing.

Peter is more familiar with zapping insulating materials, known as 'dielectrics'. He is assisted by PhD student Nigel Bish. Together they appear to have discovered a new way of predicting whether dielectrics are showing signs of premature ageing or degradation - which means their invention will help predict faults in materials subject to high voltage more accurately than ever before.

Nigel Bish Copyrighted image Icon Copyright: Used with permission 'They used to rely on 'seasoned opinion' to predict these things' says Nigel. The system he is working on uses neural networks to predict 'underlying trends' in ageing or degradation of materials. He tests out his system by deliberately instigating voids (or faults in this context) into the materials he tests. Fuzzy logic and neural networks - invented as a result of studies on how the human brain looks at the world - are for Nigel's purposes the best way of judging those 'underlying trends.

He is pretty sure that they now have a foolproof way of fault detection and fault predicting in dialectrics. Any drillion dollar companies out there who want a piece of the action?

Nigel has also discovered in the course of his work that high voltage physicists, motorbikes, rock music and guitar lovers, tend to hang out together. This might explain all those Tesla blue flames fizzing around rock guitarists' guitars.

11.30am
Dr Howson zaps a (busted) computer monitor with an arc of electricity. An arc gives a much bigger jolt as it is constant and powerful and eventually sets fire to things. But it is the very suddenness of the lightning bolt that makes it so dangerous.

'More power Igor!' Dr Howson says to Nigel as he zaps a telephone and the charge runs up the flex and out of the ear piece. Ever since the Science Shack team contacted the good Doctor he has kindly been doing tests in preparation for today's filming. His workshop is littered with stuffed toys, old TV monitors and bits of tree.

He has since discovered a passion for blowing things up with lightning he never knew was in him. His students were no less enthusiastic. 'They were so fascinated by seeing things being blown up and roasted and they didn't want to go back to their lectures' he says, smiling.

There is (believe it or not) a serious side to this demonstration. You are pretty safe inside a house during lightning but Dr H does not advise talking on the phone, as the flex is very attractive to lightning. And your TV or computer - even when it is switched off - might blow up after conducting the lightning through the cable or the lead.

12noon
Dr Howson can't resist one more test and zaps a cuddly toy donated by a student who no longer had a use for it.

He then explains to Adam things to avoid in a thunderstorm:

  • Don't stand in an open field, especially not while swinging a golf club.
  •  
  • You are safer standing on one leg than with your legs apart. Scientists have observed that lightning can run up one leg and down the other. Nasty. Cows near trees have suffered this fate.
  • If you are swimming in the sea or a lake you should be perfectly safe. There is a huge dissipation of electricity in an expanse of water (this might explain why fish don't end up being killed 'en masse' every time there is a storm). 'You'd be immersed in a vast Earth' he explains'.
  • Don't go outside, but...
  •  ...avoid telephones and computers indoors.
  • Finally, it is not a good idea to go out onto the Common wearing one of those First World War German helmets with a spike on top. While there is still something of a debate raging in academic crcles about the merits of spikes and domes in conducting electricity, Dr Howson says the spike is more attractive.

 

 
Adam Hart-Davis and Kim Bradburn Copyrighted image Icon Copyright: Production team

14th November
2pm
Chris and Jem are, as usual, nowhere near finishing the prop which will be integral to the pièce de résistance of the programme, the coup de theatre - Adam standing in a cage and staring a million volts in the eye. This is the first Faraday cage that they have ever built and, as usual, they joke about whether it will work or not.

But this time they have rather outdone themselves. This cage is already getting the envious eye from a number of high voltage physicists on the campus. Jem looks a little worried that he may be building something that looks almost professional. There are even rumours that the local lion tamer is thinking of putting in a bid.

Building the Tesla turban Copyrighted image Icon Copyright: Used with permission 2.30pm
Doctor Ken Skeldon of Glasgow University brings his one and only collapsible Tesla coil (it really is the only one in the world like it) into Dr Howton's lab. Ken built it with financial help from a government body (SATRO) that promotes the understanding of science. Tesla invented his coil a hundred years ago. It is not only a spectacular piece of machinery but it is able to generate very high voltages with little power (though there is still plenty of power to kill you).

Adam chats to Ken as he sets up his coil. Built with the Russian Doll principle each section, holding 250,000 volts, links with the next. It is as portable as a Tesla coil can get. Ken explains that Tesla's dream was to provide cordless electricity that could be delivered through the air. He thought every city, town and village could put one up in the local square and people could draw their electrical requirements from it. He was certainly a brilliant man, and this idea was not completely off beam, but the system as it was could not be described as terribly safe. His coil is still used extensively in engineering and electronics for generating those high voltage/low power currents.

'Ken's Pagoda', as we are soon calling it, looks like something out of a very sophisticated conjuring trick. He has even brought along his beautiful companion Meg Horn to help him demonstrate and test it. Unfortunately Adam keeps getting in the frame. Ken is a brilliant builder of wonderful science gadgets for teaching the 'public understanding of science' in conjunction with Glasgow University. He has an 'Arts and Sparks' show and also works with sound.

One of his demonstrations is a sound system that pumps out sound at the resonating frequency of a high quality wine glass (the sound that can make a wine glass break - like the one you can generate with a wet finger on the rim). Using a stroboscopic light you can see the rim of the glass bend up to a centimetre before the glass breaks!

Ken puts the 'Tesla Turban' onto his magical spark machine and we dim the lights. This process takes about half an hour because it involves camera people negotiating how far they really have to stand next to a million volts. Soundman Andy tries to get the amassed science experts to come to some sort of agreement as to how dangerous it is for him to be attached to his microphone boom (he eventually places it on the ground, keeping well away). His main concern is that today his kit is rented. He is quite able to countenance a million volts running down his trouser leg but he does not want the rental gear to be fried!

The Tesla coil does its thing Copyrighted image Icon Copyright: Used with permission 2.45pm
Ken lights the touch paper and retires. Actually he does nothing of the sort - he switches a switch and makes House of Horror lightning bolts dance about with a great crackling and ripping sound all over his Tesla Turban.

Adam is reassured that he is far enough away from the coil to be safe. Then Ken picks up a metal wand and waves it what seems dangerously close to the coil.

A massive crackling spark jumps to the end of the coil but does no damage to Ken because, despite holding onto the metal, the wand is well earthed. Adam has a go and starts to conduct an orchestra of flashing sparks off the top of the coil.

3.30pm
Despite the gags in today's 'zap happy' web update electricity is seriously dangerous stuff and who better to tell us than the ever cheerful Kim Bradburn who had a ghastly experience three years ago, during a lightning storm.

Her new conservatory at her home in the Midlands was dripping water and as she went in to the room to see how much water was coming in she touched a light switch and lost a large section of her hand. It has, mercifully, been rebuilt and she has movement again in her thumb. But the experience led her to find out all about lightning and how to avoid it.

5pm
Jem and Chris' spectacularly professional looking Faraday cage is ready for testing. See yesterday's Big Build for a bit more on how the cage works, demonstrated by a model of a copper man with two polystyrene balls hanging off his arms (that's a bit more like Science Shack than this flashy cage). Adam steps into the cage after he has had his 'court tasters' (Science Shack team members and Dr Ken Skeldon) have a go. Just to get the right camera angle of course.

Adam decides to take a camera into the cage and films the electric current as it zaps him.

Inside the cage Adam is perfectly safe. He can even touch the inside. But if someone outside touched the outside of the cage they would be killed by a million volts of current. This principle explains why an aeroplane is perfectly safe in a lightning storm and why staying inside your car during a 'lightning attack' is a good idea. The team leans two fluorescent tubes against the cage and one inside. The ones outside light up, the one inside does not.

6pm
Science Shack team member Jem has been itching to be zapped with a million volts so he can impress his hoards of clearly easily impressed fans. But Jem always gets the last laugh. He asks the amassed boffins of high voltage electricity, people at the top of their profession, like Drs Howson and Skeldon, what would happen if Adam took a fluorescent tube inside and poked it out through the mesh. Would it only light up in the bit outside?

Director Paul Bader, impressed by Jem's boundless energy and ceaselessly enquiring mind, but keen to get the day's filming finished, gives Jem a sideways glance, raises his eyes to the ceiling and walks purposefully off.

This leaves Jem in the lab with Drs Howson and Skeldon who are quite happy to let Jem have a go. Dr Skeldon does not believe this is an experiment that has ever been done and is not sure of the answer. Dr Howson, not a man to shirk the chance of hosting a World First in his lab, mans the light switch.

Lights are dimmed and the cage is zapped. No one is quite able to work out if the light in the bit of the tube outside the cage is brighter than the (definitely alight) bit inside. Various theories are posited, various theories shot down. Dr Skeldon reckons the gas lit up outside the cage travels down the tube. But no one is quite sure.

Jem in a cage Copyrighted image Icon Copyright: Used with permission Grant offering bodies are invited to contact Jem at Science Shack. He will gladly make use of the monies to further his understanding of the behaviour of fluorescent tubing when poked through a Faraday cage, with him, pointlessly observing it all from inside the cage.

 

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