Science Podcasts

Naked Scientists episode

Sat, 1st Aug 2009

Peeing on an Electric Fence

Electrical hazard warning sign (c) Jaumefont @ wikipedia

What happens if you urinate on an electric fence?  We find out the answer to this and some of your other science questions on this week's Naked Scientists, including why chilli peppers are red, how does squinting help you see further and what's the best way to align your laundry with the wind?  Plus, why blue food colouring could reduce the damage of spinal injury, how shrimps could catalyse biodiesel production and the physics behind the regularity of raindrops...

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In this edition of Naked Scientists

Full Transcript

  • 13:32 - State of the art facility opens at the Babraham Institute

    The Naked Scientists attended the opening of the new multi-million unit at the Babraham Insititute and bumped into Minister for Science, Lord Drayson.

  • 18:55 - Falling Mugs

    Scare all your friends by dropping a mug with seemingly nothing to stop it hitting the floor, and find out what this has to do with ice skating.

  • 26:50 - How do marine mammals control their salt intake

    If you drink sea water it dehydrates you because the salt in the water triggers osmosis at cellular level, et cetera. So you have to get the salt out of your body, lose some water to compensate. How do animals like marine mammals that are therefore eating a lot of salt in their d...

  • 30:43 - Why is TB contagious?

    Why is it that so many children died in Ireland from tuberculosis that their mothers had?



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I fear that you might incinerate your privates, or at least, develope an extremely large woodie...................Hey, hey Ethos, Tue, 4th Aug 2009

Don't do it! Chemistry4me, Wed, 5th Aug 2009

An electric fence supplies pulses separated in time, unless it is a "lethal force" military fence. This just will shock you severely. If you happen to make contact with a source of continuous potential ( either DC or AC), you are unable to stop urinating until the bladder is totally empty, provided that there is a continuous stream connecting you to the source, without the stream breaking up into droplets.

Either way is not recommended due to the muscular spasm associated with the shock, and you will definitely never do it again, as the learning will be burned in to your brain pathways very strongly.

SeanB, Thu, 6th Aug 2009

Mythbusters tackled "peeing on the 3rd rail" and extending it to electric fences in their 2004 season.  They were looking at it more from the "Guy killed peeing on electric rail" angle.

"Urinating on an electric fence can cause electrocution. (Spinoff of Peeing on the Third Rail)"

Outcome - Busted/Plausible

Upon retesting the myth on an electric fence it was found to be Plausible, but the rail was still Busted. Distance was the factor, as the urine stream breaks up less at the close range needed for urinating on the fence than urinating on the third rail, thus ensuring a direct line of current between ones body and the electrical source.

So pee from a distance and you should be fine, but then, why not just go behind a bush? mubbled, Fri, 7th Aug 2009

Erik Harris asked the Naked Scientists: First of all, I've been a listener to your show for almost a year now, and really enjoy it each week. Thank you for putting it together and sending it out for the world to listen to. Dave Ansell covered the question about peeing on an electric fence in this week's episode. In the discussion, Chris asked about peeing on the third rail (the electrified rail) on a train track, and Dave suggested that it'd probably be fatal if the person was at all grounded. The TV show MythBusters answered this question back in 2003, and then again (with respect to fences) in 2004. They showed, using high-speed photography, that your urine separates and turns into droplets on the way down (nice tie-in to this episode's discussion on rain drops), and that they were too far separated by the time they hit the rail to conduct electricity back up the urine stream. Think about the shower in your home. Turn it on and stick your hand on the floor where the water hits - you don't feel a bunch of steady streams of water from the shower head, you feel a bunch of droplets. Because of this, if you're peeing on an electrified rail at ground level, while standing, you're almost definitely not going to get electrocuted. Personally, I'd still advise against it, just in case, through some odd quirk of chance, there was a brief instant where the droplets weren't suitably separated. It's different with an electric fence, though, because it's vertical, and the urine stream doesn't have time to separate into droplets. So, if you were to kneel next to the third rail and pee, you'd almost definitely get zapped (and presumably killed). Erik Harris What do you think? Erik Harris , Fri, 7th Aug 2009

Tim Hanes asked the Naked Scientists: Hello Dr. Chris, First, let me tell you I am a great fan of the Naked Scientists. Please keep up the great work! Now to the point: To my chagrin, I have to admit having thought about the pee on the electric fence issue quite a bit. I, like Dave, grew up in a rural area and was also cautioned about weeing in the wires of electric fences. I always suspected that this was a myth. I agree with you that this really needs confirming in the kitchen. One significant issue, I suspect, is the distance of the urine stream in question, from the wire because the further down the stream you go, the more the urine will break up from a "solid" stream into a grouping of droplets (much the way a shotgun blast spreads out as it travels toward a duck). For this reason, I think that peeing on the power rail in the underground would be harmless (sorry Helen) because by the time the stream got down to the rail, it would be too dispersed to conduct the current back up itself to the point of issue (to put it politely). Please get Dave to take this to the kitchen! Cheers, Tim for Germany What do you think? Tim Hanes , Fri, 7th Aug 2009

Tyler novak asked the Naked Scientists: Hi, Tyler here at Work in Maryland here in the states. I am listening to your latest podcast right now and I have something info to offer having to do with the "peeing on the fence" subject. Mythbusters actually did a segment on this and originally called it busted because 1: they tried it with an experiment and did not get a charge and 2: when viewed with the high speed camera, they saw that what looks like a constant stream of urine actually quite quickly becomes a broken stream of droplets. Due to these droplets preventing the electricity from coming up stream, they called it busted. Although in a later show, someone had wrote in saying it happened to them, so in conclusion, they showed that in most cases you would not get a shock, the only time where it would be very likely is if you were literally inches from the fence when urinating, before the stream gets a chance to break up. I love your shows and hope to hear more from you in the future. Good Testing! What do you think? Tyler novak , Fri, 7th Aug 2009

Michael Desmond asked the Naked Scientists: Dr Chris, Dairy farmers are aware that certain flavour taints can come through in milk, I know from my grandfather, if milking cows ate cabbage the milk would be tainted, I know that sometimes silage can taint milk, good quality silages does not. † Michael Desmond. Waterford, Ireland What do you think? Michael Desmond , Tue, 11th Aug 2009

Alex asked the Naked Scientists: Hey Naked Scientists, love the show - you guys have been a part of me discovering my passion for science. Thank you. I was also just wondering about your usage of the word current in your previous podcast when you were talking about peeing on an electric fence. Since current is the rate of flow of the electrons wouldn't it be more proper to say, for example, "Is the current fast enough to be harmful?" as opposed to "Is there enough current?". Thanks a bunch, keep up the great work! Alex Pickering What do you think? Alex, Tue, 11th Aug 2009

brad tittle asked the Naked Scientists: Check out the Mythbusters episodes on the subject. One of the problems I discovered recently is that urine going out of our elevated tubes doesn't stay solid. The surface tension of the stream causes droplets to form rather shocking close to your penis (your mileage may vary). Once that droplet is formed the path for conductivity becomes challenged. The Mythbusters had a really difficult time trying to make the third rail method work at all. They ended up cheating heavily. -- Brad Tittle Tech Support What do you think? brad tittle , Tue, 18th Aug 2009

So John here has wasted his time ? ...

Apparently people defecate outside his shop too,
maybe the shorter orifice-wire distance involved will mean the circuit is completed.  

(cave canem) RD, Sat, 24th Oct 2009

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