What Happens in a Cable Strike: LV, HV and the Person Holding the Tool

0:40Good morning, everyone. Hopefully, you can see me. Welcome to Sygma HQ. Few issues this morning. For some reason, it put a password on the room, so. Oh well. I think everyone's got here.

1:00As always, guys, just give it a couple of minutes for people to get in the room. I was a bit late opening up this morning because we had a an issue with a couple of people getting in. So, just let everyone jump in.

1:17Just while we're waiting, guys, um excuse me. Sorry. It's not corona. I've just been drinking too much coffee and vaping too much. Um let me know what job role you're in, guys. What what do what do you do? Um just just it's handy for me if I know what kind of audience I've got so I can tailor it a bit. Are you health and safety, or excavator, utility surveyors? Give us a idea of your job role. Chuck it in there. Also, is it anybody's first time with me today? Anybody here for the first time?

2:06Okay, good mixture.

2:21If anybody has been here before, you might realize I've changed rooms. Um we've got a a real course in the in our training room, so I've been relegated to the spare office. I'm afraid. It's not as nice a room, unfortunately. And the lighting's not great, either. But there you go.

2:43Okay, I think we've got everyone here that's coming in. We have got a few new people, guys. For those that have been here before, just excuse the intro. Um my name is Pete Ashcroft. I work for um Sygma Solutions. Wrong side. It's always reversed in the in the camera. We're a a specialist training provider in utility location.

3:04Um it's the only kind of subject we we we teach in. We do one-day courses, two-day courses, five-day courses, but it's all geared around around um utility detection and avoidance. And we're running these uh free kind of mini-series of webinars, which are like sections from our normal course. Um so, they're like little snippets, if you like, of of what we teach people. So, I hope you find them educational.

3:26Um my personal experience, very quickly. I started with Radiodetection at the age of about 19, 20. Um long, long time ago. Um worked with them for a while. I've worked with utility mapping companies, and now I'm obviously concentrating more on the training side of it. So, I hope you find it um enjoyable and useful. Bit on the software, guys. I like to keep these interactive. So, please, guys, get involved. Chuck comments in there. Ask me questions.

3:51If if you don't understand something, throw it in there. The only thing with the software is there's a slight delay. Uh what you're hearing now, I probably said 10 seconds ago. So, that makes it a little bit tricky when I'm asking questions. I've just got to pause for a while and wait for your responses to come in. Um but we can try and manage that as we as we go through the session today.

4:09It's the the most difficult thing about delivering online is not being able to see your faces. On a face-to-face course, I can kind I can kind of see and judge if people understand what I'm talking about and if they're in agreement, or if they're asleep, even. Um it's difficult on a webinar, so I will be just jumping in now and again asking you for a bit of feedback just to ensure that um you're understanding what I'm talking about as we as we go through it. It's important that we understand each step as we go for the next step to then to then make sense. Okay, guys?

4:39So, this section that I'm going to cover with you this morning um is from what we call our reasons for using locators section. When we deliver a training course on a cable locator, the first thing that we do is talk to people about why it's important um to to use a CAT and Genny, for for example. Okay? We have got one or two utility surveyors in here, guys. Just bear in mind that this

5:00section of the presentation is aimed at the guys that are actually doing the excavations. These are the guys on the ground digging holes, um putting themselves in danger. Okay, so it's aimed at them. But as a utility surveyor, it's it's good that you see this because it'll re- it'll uh emphasize how important is the work that you do when you're out there mapping these utilities. Okay, so without further ado, I will kick off. And hopefully, you can see and hear me okay, guys.

5:27I'm going to um put my screen share on. There we go. Make me a little bit bigger for you. Don't know if that's good or bad, but there you go, guys.

5:56As I said, guys, um we we talk about the reasons why we use locators. There there are there are many reasons for it, and you can see a few of them that are listed up there. I'm I'm sure you can probably think of other reasons as well why it's important that we use a um a cable locator. The one that we'll concentrate on this morning in particular is the first one, and it's operator safety.

6:19Um to me, when we're dealing with the guys that are on the ground, this is the most important part of it. It's for safety. I worry um in recent times that we're losing sight of this a little bit. We hear people talking about um preventing damage and and costs and everything else, but we we need to make sure we don't lose sight of the main reason why we're doing this, and that's to protect people from being injured at work when they're working on underground cables. And that's the section that we're going to concentrate on today.

6:46If you strike an electricity cable, you can get injured or even killed off it. I'm pretty sure everyone in here accepts that and understands that. So, we're doing it primarily to prevent injury or death.

7:02I want to throw a question out to you guys. What kind of injuries would you expect to get off an underground cable? What do you think would happen to you if you struck an underground cable?

7:16And then just while you're answering that, hopefully, you've stuck your answers in there now, guys, I'm going to show you this picture. I don't know if anybody recognizes that picture, but that picture is from the front cover of HSG47, which is the HSE guidance on avoiding

7:35So, you may recognize it. The picture, though, a lot of people don't realize this now, especially the younger generation, the picture is taken from an old video. It was called Alive or Dead. I don't know if anyone remembers it. It was done in the '80s, and it was an old HSE video. And on the video, that's actually a dummy. They strap a dummy onto a jackhammer, and they remote control it through a cable.

7:56The point I'm making with this, guys, is that's a real explosion coming off an underground cable. And if you look closely on the bottom right, you can actually see the cable there. Okay. There has been companies that have done it since this. They've they've replicated this, but as far as I'm aware, and I could be wrong, they've always done it with explosives. So, they've kind of replicated it, but this original one was a real genuine blast coming off a low-voltage cable. And and quite rightly, guys, the answers that are coming in are burns, severe burns, etc. Okay. That's the main injuries that we get off underground cable.

8:32One of the myths of underground cables, if you like, is is around the area of electrocution. It's extremely rare that you will ever get electrocuted through striking an underground cable. Very, very rare. And I can honestly tell you that in in over 20 years of doing nothing but this, I honestly don't think I've come across a single genuine example of someone that's been electrocuted on the initial strike of an underground cable.

9:02You see lots of headlines in the news saying that workers suffer electrocution, etc. But actually, when you go into the details, they didn't. They suffered burns and explosive injuries. It is not very often at all that electrocution occurs through striking a cable. And the reason that I want to talk about this, guys, and the reason I'm bringing it up is that I think it's important that we educate people properly on the use of insulated hand tools, things like these.

9:32I've seen a massive increase in the emphasis that companies are putting on insulated hand tools over the last five or six years. And my concern is that, well, I'll give you an example. We've done some work with some apprentices recently, some younger guys. And when I got talking to these guys, they genuinely thought that hitting a cable with an insulated tool would stop them getting hurt.

9:56I'm not saying these are useless. I'm not saying we shouldn't use them, but we have to understand what they will and won't protect us from. Insulated tools will protect us from electrocution, but remember what I said, the chance of that is is is is almost impossible. It's very, very remote that that would happen. Okay. You're more likely to get burnt from underground cable through the explosive effects of arcing current. And if we look back at this picture, guys, would an insulated shovel or an insulated bar stop that burning you? And it certainly wouldn't stop it happening.

10:32Okay. So, just to be clear, yes, there is a use for insulated tools. Yes, we recommend that people use them, but we need to make sure that the guys out there understand that, unfortunately, they will not stop them getting burnt off an underground cable, and that is the most likely thing that's going to happen when you hit them. One more point on insulated equipment, guys. Let's make sure we're educating the guys when we give it out. A lot of the guys that I see on site, if I ask them what voltage those are rated to, quite often they don't know. Okay. Some of the good ones, you see, will be rated to 1,000 volts with a flash voltage of 10,000.

11:07Think about high-voltage cables, guys. The bulk of the HV network is 11 kV or above. Okay. Yes, we get six, you know, but the bulk of it's higher than that. Okay. Now, guys, I don't want you to take my word for this. I want to explain to you now, logically, about what happens when you hit an underground cable. And I think I've got another question for you. What injuries would you get if you touched an overhead cable? What would happen to you? Okay. So, the question I asked before on underground cable, I think everyone said burns, severe burns, blast injuries. What would happen with an overhead cable? What are the differences?

11:45The other thing that you'll notice with an overhead cable, I'm sure you've seen videos before and examples of overhead cable contact, they don't tend to get this I call this the volcano effect, an eruption of flame and fire. And it's quite prolonged. It can last up to three seconds. We get this huge blast of flame and fire. We don't tend to get that on overheads, guys. You might see the lightning bolt kind of arc across, okay, but you don't tend to get this same eruption, this same flame when we make contact with with an overhead usually. Yeah, absolutely, Kerry, electrocution.

12:22So, what we're trying to what we're trying to what we're trying to say here, guys, is, can you see there's a difference between overhead and underground in terms of the injuries that we get and in terms of the reaction when we make contact with them? So, there's a difference there. So, let's start looking at what that difference is. Now, guys, when you signed up for this webinar, on the registration link, there should have been a warning on there about graphic videos. And you're still here, so I'm hoping you're okay with them, but I will warn you again that we have graphic videos coming up, people being electrocuted and cable strikes of people being burnt. So, if you want to disconnect, guys, I won't take any offense, but you have been pre-warned of what's coming up. You may have seen some of these before.

13:44So, obviously, guys, not a nice video. He's been killed there. It reminds us of the dangers of overhead cables, guys. But he was obviously killed there. Okay. I've got another one coming up, guys. While you watch the second one, what I want you to consider and I want you to give me an answer on this is, why he was actually electrocuted? What did he do? And and to give you an idea where I'm going with this, what would happen if a bird landed on that power line? What would the difference be? Have a think about that and chuck some answers in the chat box while you watch the next one.

14:38Once again, he's been killed, guys.

14:40Once again, he's been killed, guys. I think it's pretty obvious he was probably killed instantly when he made contact with that. Well, I don't know how I've managed to do that, but I've ended up with subtitles on here. That's pretty cool, actually, but I don't know how I've done it.

15:20I have no idea how I've done that. It's pretty cool. Anyway, I can't think of how to turn it off, so you'll have to bear with the subtitles. Um, just give me a second, guys.

16:00Sorry about this, guys. Just give me a second. I'm just seeing if it's really annoying me, so I just want to see if I can turn it off. I can't. Anyway, okay, guys, you've got the answer anyway, guys. Um,

16:20yeah, he was in contact with ground, um, via via the via the train, via earth. And that's why a bird can land on it. Um, so so what we're trying to establish there, guys, with those with those graphic videos is that electrocution occurs when the current passes through your body to ground, okay? That's why we get electrocuted. But the other thing that we need to understand about electricity

16:42is that it will always take the path of least resistance. And if you ever if you join me on my Genny sessions, guys, or if you've been on a Genny session, we talk about this um quite a lot on the on those sessions about paths of least resistance. And it's the same with any electrical current. It's looking for the easiest route to ground possible. Um, and that's why we have lightning conductors and things like that. So, I just want to share a little story with you guys, um, and an example of this. I'm going to turn my screen share off for a minute so I can stand up and show you.

17:08Uh, this was quite a while ago now, um, about 10-15 years ago. Um, a young man picked up um a long metal flagpole off the floor. So, he's picked up this long metal flagpole, and he's levered it upright. And as he went up with the pole, he made contact with an overhead cable. Luckily for him, the pole was touching the floor. So, the current went straight down the pole and into the ground, burnt his hands on the way past, but it didn't kill him, okay? But can you see that if the pole was off the floor, then the current would have passed through him instead, and it would have killed him? Okay, but because it was touching ground, that created that easier path back. Does that make sense, guys? Do you do you understand that? Do you accept that?

18:10Okay. So, on that same theme then, let's just carry on and show you another example. This is, um, I don't know if you've seen this before, guys. I figured out how to turn subtitles off as well, by the way. Um, I don't know if you've seen this before. This is in China, and they've and they've got scaffolding, and we've got overhead cables on the top left-hand side. What I want you to notice with this scaffolding is that it's not on the floor. There's no metal in contact with the ground. So, the the only they've got four rubber wheels on each corner, effectively. The only thing making the circuit between the scaffolding and the floor is the people that are pushing it. And they've all just been electrocuted.

18:49It's still pumping current through them. And if you look on the left-hand side, guys, the guy there, he actually hangs on the longest. Um, and he's the only one that manages to get up and walk away from this. I don't know how long he survived for afterwards. You'll see him still hanging on.

19:15Eventually, he drops off, and I'm just going to fast-forward it. Watch what he's been on the floor about 2 minutes here now. Watch what he does now. He's electrocuted again. How unlucky is that? If you keep watching him, he still manages to get up and walk away.

19:40Well, what I want to show you with that video is that if that scaffolding was actually on the floor, if the metalwork was touching the floor, they'd have had a better chance of surviving it. But the it had no other way way to go. It had to come through them. If we go back to the beginning here, watch the guy here on the left again. Look at his feet, and you'll see the um current pass through his feet. You see that? They just get stuck to it, Kerry. When you get electrocuted, you can stick and and hang on to it. Um, it kind of grips your hand, if you know what I mean, so you're you're stuck to it, effectively. It like tenses the muscles in your hands, so you grip on. It's very common with electrocution, that.

20:20So, what I was trying to establish there, guys, in in quite a graphic way, I admit, is that electrocution occurs when the current passes through your body to ground, okay? However, if there's an alternative path of lesser resistance available, the current will pass through that instead. Do you accept that, guys? Are you are you in agreement on these two on these two principles? While you answer that question, um, I'm just going to go grab some water, guys.

21:21Great stuff. We're all in agreement. That's what I like. Okay, so now we understand that principle, um, and we accept that, let's now kind of, if you like, transfer that theory onto underground cables and look at some of the differences that we have with underground cables. So, there's an array there of different types of underground cables. Remember, guys, this is UK-based, so I don't know if anybody's tuned in from overseas. Um, I think everyone's UK-based, but this is this is based on the UK network. The the top ones are are LV. The top ones are low voltage.

21:30like transfer that theory onto underground cables and look at some of the differences that we have with underground cables. So there's an array there of different types of underground cables. Remember guys, this is UK-based, so I don't know if anybody's tuned in from overseas. I think everyone's UK-based, but this is this is based on the UK network. The top ones are are LV, the top ones are low voltage cables. The bottom ones are high voltage cables. Okay?

21:54So there's no two cables exactly the same, they're all slightly different. However, they've all got one thing in common. They all have this metal sheath underneath. What's it called, this, guys? Every cable has it, this piece of metal, if you like, underneath the outer insulation. All these cables have it.

22:19And I'm just going to show you a real example. Turn my screen share off again for a second. Well, it's not great, you know, guys, but I've got a damaged HV cable here, can you see that? So, it's just been hit, but if you look here, again, the phases are inside and then we have this metal round the outside of that cable. Can you see that?

22:43Oh, every time I do that, I get oil all over me. And David has hit the nail on the head. It is the earth. Okay, every cable has this earth underneath the outer insulation here.

23:01So, let's just use this one as an example here, guys. The dangerous electricity current, if you like, is on these phases inside. Whoops. Yeah. To touch that, though, where the electricity is, what do you have to pass through? Can you see that, guys? You can't touch that without first of all passing through this. Yeah.

23:22So, now I'm being full screen. It doesn't matter what tool you're using. Could be a digger bucket, could be a jackhammer blade, could be a shovel, you could be knocking a pin in the ground. That tool has to first of all physically penetrate that earth, okay? So, it's going through the earth, and then while it's in contact with the earth, it then hits the phase.

23:44Okay, you're holding onto this, remember. But which is the best way back to ground? The path of least resistance is to the earth and then down the earth, not through you. You could get a bare metal bar and slam it through a cable, and you wouldn't get electrocuted because the current would sooner go that way than than through your body.

24:02We do not do practical tests for that, guys, so just take my word for it. What what you can maybe relate to this a little bit more, now as you can imagine, doing these courses for so many years, I'm often told stories of cable strikes. I hear hundreds every year. One of the common ones I hear, just as an example, is, "Oh, we had a guy on site and he had a road pin and he hammered it through through the ground and he hit a cable and it was a miracle he wasn't electrocuted."

24:29I have heard that hundreds of times, guys. Hundreds of times, a similar variation on that story. I have never once heard that story where the person was electrocuted. Okay? It's not a miracle. Okay, it's just physics, if you like. The other thing to consider as well, guys, is this. This is another thing that minimizes the risk of shock.

24:48Let me um just go back to here again. So, if you remember, guys, the main thing that protects us is the earth. We've talked about that. But let's let's look at a different example. I'm crap at drawing, by the way, guys. If that's the ground, and that's our cable, let's say the cable doesn't have an earth, yeah?

25:07We've got the man stood up here, and he hammers that pin through the cable. Why would the current go all the way up here and back through his body to get to ground? That's not the easiest path, is it? There's no way it's going to do that. It's going to hit that pin and go go to ground. The pin's already in contact with ground. And I'm not saying always, but nine times out of ten, when you hit a cable, whatever you hit that cable with is in contact with ground at the same time.

25:31So, there's a few reasons which minimizes that risk of shock. Now, guys, remember what I'm saying though here. I'm not saying you wouldn't get injured. I'm certainly not saying you wouldn't get injured. But this is where it's different to an overhead. Let's go back to this picture. What have we just done then when we hit this? We've hit this cable, we've pushed through the earth, and we've hit that phase inside. Hopefully, you can see where I'm drawing that.

25:51And what we've just caused now is a short circuit in the cable. By the way, guys, is this all making sense so far, guys? You follow me along okay with this? Again, it's difficult because I can't see your faces. So, we've just caused a short circuit between two conductors in that cable. Now, bear in mind, if you've hit this cable hard enough, you could have caused all three phases to touch together.

26:10So, we then start off this chain reaction which causes the explosion. We have a short circuit. The first thing that happens with a short circuit is you get a massive increase of current. We get a huge surge of current at the point of impact. When we get an increase of current, we then get an increase of temperature, so the cable gets very, very hot.

26:31To give you an idea how hot an underground cable gets, an LV cable, low voltage cable, can get to 19,500 degrees C. Now, I'll give you an idea how hot that is, guys. The surface of the sun is 5,000 degrees C. So, nearly four times hotter than the surface of the sun is how hot that cable's going to get when you hit it.

26:51I'm sure some of you in here, especially if you're involved in health and safety, would have seen holes blown out with, you know, digger buckets, jackhammer blades, that kind of stuff. The cable I showed you before, you know, the heat is incredible. So, surge of current, massive increase of temperature. What happens when something gets hot? What does it do? Think about what happens to its size. It expands, doesn't it?

27:13So, the current shoots up, the temperature shoots up, and the whole thing expands, and we get this release like this coming off it. Okay? The problem we have with an underground cable is it's not just the fact that all that expands, it's how quick it does it. It goes from normal temperature to 19,500 degrees C in less than a second. The expansion is a rapid expansion, it causes a pressure wave.

27:41We talk about cables being unexploded bombs, and it's very, very true, guys. Um, it's very, very similar because it's the same way as a bomb works. A bomb is simply combustible material, you ignite it, it gets hot very quickly and expands. If you think back to any movies you've watched with bombs going off, you can see the pressure wave that destroys things. It's the same.

27:59You might have heard of people hitting a cable and being blown out of the hole. It's exactly the same thing. It's not the electrocution, it's the pressure wave caused by that massive expansion. Okay? So, as I said again, to repeat, increase of current, increase of temperature, the whole thing expands. Okay? And that's what injures us.

28:15One of the worst cables to hit is a cable made of copper, the old cables. There's a few issues with copper. It's got quite a low boiling point for a metal. So, you know, things go from a solid to a liquid to a gas when you start to heat them up. Copper will melt and turn to liquid at about 1,000 degrees C.

28:31It will then boil and turn to gas at 2,500. Remember how hot the cable gets, guys, 19,500. So, well within that temperature range, the copper content of that cable vaporizes. When you boil copper, when it vaporizes, its mass expands by 67,000 times. So, a piece of copper the size of your thumb will get 67,000 times bigger. That's how a cable explodes, guys. And that's the difference, and that's why the risk of shock is so low on underground cable. So...

28:40copper content of that cable vaporizes. When you boil copper, when it vaporizes, its mass expands by 67,000 times. So, a piece of copper the size of your thumb will get 67,000 times bigger. That's how a cable explodes, guys. And that's the difference, and that's why the risk of shock is so low on underground cable. So, let me be clear on this, just to summarize.

28:55We're going to be in full screen again. If I get a bare metal bar with no insulation and put it through a cable, I probably won't get electrocuted, I'll probably get burnt. I got an insulated metal bar and put it through a cable, I probably wouldn't get electrocuted, I'd probably get burnt. Can you see the message there, guys?

29:10It doesn't matter if that tool is insulated or not, you are not going to stop the cable exploding and you're not going to stop getting burned, unfortunately. I hope that all makes sense, guys. As I said, I want to be clear, I'm not saying not to use insulated tools, I'm just saying that we need to make sure that people understand what they will and will not protect them against.

29:25You all okay so far, guys? Hope that makes sense to you. We're going to move on now and look at some examples of cable strikes, but just want to make sure that everyone's okay with that. If there's anything you want me to expand on in there or explain upon, or any questions on that, then then chuck it in there before we move on to the next section.

30:10Okay. So, I'll start moving on, guys, while you're while you're answering that. You remember that picture that um that I showed you before. Oh, I need to turn screen share back on, don't I?

30:25So, you remember this picture I shared with you before, guys, and you'll probably remember that I said it was from um an old HSE video. Just going to show you the clip that that's from.

31:13The next one is um a real one. So, this is in Romania. Not quite as dramatic, but it's real. Just seen him manage to jump out of the the way there at the back.

31:33This is a little bit more serious, guys. Again, this one is real. It was CCTV footage um it was in Stockport, near Manchester. It's it's a while ago now. If you look at the top, guys, you see the two guys working here, and they're they're basically relocating the column. They're digging a new hole for it. No barriers, no plans, no CAT and Genny. You'll see people walking right past them. They were lucky they didn't hurt anybody else when they were doing this.

31:58On the left-hand side of where they're working, there's a box here. You can see that. That's a power pack for a portable breaker. You you just saw him bend down then with his hand in the hole. They've come across a piece of rock or concrete they can't shift. So, he was having a look at what that was. And he's now got the hand tool back in there again.

32:20He's decided the only way to move this obstacle now is to put the breaker back in, and I want you to watch this closely and watch how deep it goes when he puts it in. It's gone in so deep that that just to operate it, just to pull the trigger, he's got to get on his knees. And he hits the cable. Watch it in slow motion, guys. Look at the speed of it. He doesn't even get a chance to pull his head back out of the way.

32:51The next one's going to zoom in, so we lose a little bit of quality, but the message is still there, guys. The speed of this is frightening, completely engulfed in flame.

33:05This one's a more recent one. You may have seen this one, guys. It's been doing the rounds on social media and and such like. Again, it's real. It was outside the House of Lords, I believe. Look at it again in slow motion. Look at the V-shape of his head, and that gives you an idea of how much his face has taken the impact of that blast. Look at the molten metal coming down. Look how hot it is on the ground. Shrapnel, guys, yeah? Like a grenade going off.

33:30I don't know how he manages to get up from this. Just the pure adrenaline, but if you look at him closely now, look at his his bottom half. It's just ripped his trousers off him.

33:47When I when I first asked you this morning about what happens when you hit a cable in terms of injuries, I think a few people talked about um internal burns and lung damage. And there's not, believe it or not, there's not that many people killed on underground cables compared to how many cables get struck. But when people are killed, it generally is caused by irreparable lung damage, and also a lot of the major life-changing injuries are caused by the same thing. And what happens is,

34:11you may have heard of this before, in every human there's an instinct in us, and it's called the flight or fight instinct. You may have heard of that. And that instinct kicks in when something frightens us. And part of that instinct kicking in is that your body subconsciously takes a deep breath because the idea is you're filling up your muscles with oxygen ready for your next move, be it flight or fight. And while you may have seen a real example of this, have you ever jumped out on someone and frightened them?

34:34What do they do? Like that. And as you've seen now with these pictures and videos, guys, can you see where people's faces tend to be when they hit that cable? Right in the mix of that flame and heat. And they do this and breathe it in, and it causes really serious damage internally.

34:57Few few pictures, guys. These are old ones. They've been around a while, but we talked about this before about the amount of metal and and what it does to the metal. Remember, that doesn't just evaporate and disappear. That comes out as shrapnel again. That's the guy that was using it. It happened a long time ago, this, guys. Second view of him.

35:19This next one is a chap that cut through a cable on the assumption it wasn't live, and it was. We expand on this a little bit more in the in the normal courses that we run, guys, but one of the things we need to understand is there is no instrument on the market whatsoever that will tell you if a cable's live or dead. Okay? We don't have the technology to do it. That's why electricity companies spike cables.

35:52Okay. So, this guy cut through it. You can tell it was live. That's his vest and his hat. That's his face. You can just see where his hard hat kind of protected him. But I also want to make the point with this, guys, is people do think that, well, I've got insulated handles here, even if it is live, I'll be all right. But do you see what we're trying to say? It's the flash that gets you, the burn. It's that short circuit you're causing by by touching those cores together inside that cable.

36:09Got a little video of him doing this. Show you. You can see him in there now, guys. With that still saw. You might see his arm go as he's firing that up.

36:27Yeah, absolutely, Jake. Absolutely. The other the other thing with this, you've seen the other thing with this, guys, as well is, forgive me going off on a tangent, but this is where I've got a lot of frustration with HSG47. If you look at HSG47, there's a section in there that says, once you've located a cable, determine its status, i.e., is it live or dead?

36:48It's it's impossible to do. But, of course, because that's written into HSG47, people reading that thinking, well, it must be possible. Why would they be even asking that question? And and since the new HSG47 came out, I've honestly seen um an increase in the amount of people that believe it's possible. Okay, when it's not. Okay.

37:08This is um one that happened in uh in London quite recently. This is after the event, basically. This is the aftermath of it, guys. [no speech]

37:32You need help, man. You need help. You see all the skin hanging off his hands and the state of his legs.

37:45Don't put no water on him, yo. This next one, I think, just shows the excavation he was in. Look at that, guys. [no speech]

38:05There you go. So, to finish off on a couple of things about electricity cables, guys, one of the things that we need to be clear on is that low voltage, LV, is just as dangerous as high voltage when it comes to underground cables. I often see sites that I've worked on where, because there's HV there, people take more care with the HV.

38:26High voltage will cause more disruption, it will cost more money to fix, but in terms of personal injury and the risk to the to the worker, LV is just as bad. In fact, I would argue it could be worse. The difference between the two systems is if you look on the left, we have a circuit breaker. That's what we use to protect a HV circuit. And on the right is a fuse, old-fashioned plug-in cartridge fuse. That's what we use on LV.

38:50The difference between the two systems is the speed in which they trip out. Some HV circuit breakers, now vacuum breakers in particular, 75 milliseconds, almost instant. LV fuses can be a second or more.

39:03Think back to what we talked about, guys, about how that cable explodes. The build-up of current, the build-up of heat, the expansion. It needs time to do that, and the more time we give it, the bigger the bang. Okay, so as we said, low voltage can give it that bit longer. We can get just as big an explosion off an LV cable as we can off a HV. So, treat them both with the same respect, treat them both equally. They're both dangerous.

39:33What's also very important, and if you've done street works courses in the past, guys, I'm sure you'll have covered this, is if you do ever hit a cable, you keep away from it. Okay, you get back, you barrier it off, you don't go anywhere near it. You certainly don't do like that on the picture and start trying to tape it up.

39:51You may have heard about this before, guys, but there's a danger um with electricity cables, particularly on HV, but you can have it on LV, and it's called an auto-recloser. And the stories you might hear about this is where this the the cable trips out, and it waits 30 seconds and kicks back in, and then it trips out again, waits 30 seconds and kicks back in, and you end up with three explosions.

40:10I'm not going to go into too much detail, guys, but the reason for the system is for overheads. It was for temporary faults. A lot of the time you get a temporary fault on an overhead, and it doesn't damage the line. Um so, this was a quick way of kind of getting the power back on um um very quickly. But because the networks are linked, it's on the underground network as well. So, to give you an example of of what can happen and what has happened, there was a guy injured um doing this in in Rochdale a few years ago.

40:36You hit an underground cable, and it goes bang. You jump back and shit yourself. Okay, you're lucky that you didn't get injured. But then you calm down. And what do you do when you calm down? What's the first thing you want to do? You want to go and have a look, because it's human nature, isn't it? We're nosy buggers at the end of the day. So, you want to go back over to that excavation and stick your head in the hole. The auto-recloser kicks back in,

41:03and you get a second explosion. Okay, so so we need to emphasize that, guys. If there's ever a cable strike on site, we keep away from it. Okay, I've got a couple of quick videos to show you. The first one's in America, but it's the same system. On this video, you'll not see the initial strike. They've hit the cable with a digger bucket, and then they start videoing. So, the explosion you see is the secondary blast when the recloser kicks in.

41:19Is all this making sense so far, guys? Just chuck me some I I worry when the chat goes quiet. So, just chuck a few comments in there if you if it's all making sense and you're still following.

41:27[no speech] Oh my god. It's fucking welding, isn't it? Dude, I got to get the bucket off it. You can't. I have to. You can't. I have to. Dude, you're crazy if you fucking try.

41:52That's fucking my bucket all up. This is a similar one, guys. There's actually someone working in that excavation, and you'll see the point where he hits the cable because the camera goes off. Right on cue. It it comes back on again. He's actually still in there. That's why his mate's looking for him.

42:14See him pop up there? So, it it kind of starts to calm down a little bit now. And they start making their way back to it.

42:36Oh, sorry, guys. It just paused a minute. There we go.

42:54So, very, very lucky, guys. Okay. This was um um Pimlico Road in in London a while ago. Um and and I use this to highlight how dangerous these cables are. This is actually an old link box. But the the point I'm making here, guys, is that the network is so old and knackered in places.

43:18Sometimes just the compaction of the ground around these cables is all that's holding them together. So, we've got to be so careful when we're actually um exposing them and working round them. They reckon in London alone, just in London

43:34...it's pretty frightening. This, this here, you can see, guys, it wasn't an excavation. This was a cable that exploded, basically. Blew a big hole in the footpath. The guy on the corner here is kind of trying to phone it in. And it also highlights that the, the secondary blast, if you like, watch what happens here.

43:57Frightening, isn't it?

44:01That's, that's my section on hitting a cable, guys. Um, if you want, I've got a bit of time. I've got a few slides on high-pressure gas pipes. Do you want to stick around and show you them? Just, just say yes. If you want to disappear then, then guys, go for it. But I've got a few, it's only a couple, it's only another five minutes, guys, if you want to hang around. I just, I'm just conscious that I didn't put that in the agenda, if you like. So, but I'm quite happy to share it with you if you want to hang around for a minute.

44:35Cool, let's go then. So, moving on to, to gas, guys. Um, I don't think I need to bore you too much with the danger of gas. It's obvious, isn't it, guys? Yeah, we get a gas leak, get an explosion, cause asphyxiation. I know some of you guys here are working with gas as well. So, um, what we also have in the UK is, um, high-pressure gas pipes. Critical pipelines, in effect. And, and I don't know if you've seen any of this stuff before, guys. Seen these before? And these?

45:06You'll have these down the routes of, um, high-pressure gas pipes. You also get them on chemical pipelines and fuel pipelines and stuff. Um, so there's, there's quite, um, an extensive network of, of high-pressure gas. Just one more point on that as well, guys. We're doing a little, um, session, um, with Line Watch tomorrow. Line Watch look after all of these pipelines, the, the chemical and fuel pipelines, and they're doing a free webinar. So, I'm jumping on that tomorrow, so. It might be worth you watching if you're interested. Anyway, the, the reason for these, um, these, these marker posts, they're what we call aerial markers.

45:35And the idea is that on a regular basis, um, a helicopter will fly the route of these pipelines, and the markers enable the kind of pilot to see where the pipe goes. And, and they're making sure nobody's digging or working near it. We often do courses and lads will say, "Oh, we had a helicopter land on us and ask us what we're doing." You know, so, so they, they take it really seriously, basically. Um, and, I, I, I've, I've never found an example in the UK of a high-pressure, high-pressure gas pipe being struck. There's been a few medium-pressure and suchlike, um, and stuff, but I, I don't think we've hit a high-pressure one. Again, correct me if you, if you know of one, but, um, high-pressure, I don't think so. But anyway, let me show you why they do this. This happened in America a few years ago.

46:14This was a high-pressure gas pipe that exploded. And it's only when you look at that crater in relationship to the men that are stood around it, you get an idea of how big that actually is. Frightening, isn't it? That's another shot of it. The next one, though, we're going to zoom right out. So, check this out. Look at that blast radius. So, that's the, the, there's an excavation there, that's the, uh, crater we were looking at. Look at the blast radius of that.

46:42So, if you ever wonder why they fly up and down these pipelines in helicopters, making sure nobody's digging, this is why. It's tremendous. Nearby house, what it did to it. This one is, um, another one, guys. This was in Texas, and they were drilling holes to put, um, telegraph poles in, for overhead power cables. Um, and just watch what happened. It's quite interesting, very, very short video, this, guys.

47:22And what is developing now, a natural gas explosion in the northern part of Texas. We're hovering about three-quarters of a mile away from this fire, and the heat is incredible up here in the cockpit.

47:40From the news station, this is a Fox 4 news alert. Conflicting reports from the scene on the number of casualties, but...

47:55...that first explosion lasted for about 10 minutes, where the house was shaking.

48:03My, this thing is huge. And so, your pictures are live right now. No specifics on what went wrong, but obviously, that gas line was struck and ruptured. Oh, an eight-man crew drilling for the electric company, uh, those holes for the power lines, when they accidentally hit that main gas line.

48:35So, this is a bad scene, and emergency crews haven't really been able to get in there close because it's so hot. The explosion was so big and the chaos was so bad, the numbers all afternoon were across the board. Sky 4 continues to give us a look at the smoldering aftermath. The only person missing is the person who was actually driving that heavy equipment. This was a 36-inch pipe with high-pressure natural gas. That's a telling picture right there.

49:14I think you get the idea, guys. I'll just measure, finish off on a, on a couple of slides on water. We don't normally associate water with danger, but it is dangerous. High-pressure water can be really dangerous. Think about what we do with high-pressure water, what we cut with it and stuff. So, quite key to look at. This next one gives you the idea of the power behind a, um, a water pipe. This is, um, a pumped sewer, I believe. Look at that. Absolutely incredible. And it just gives you an idea again of the power behind high-pressure water.

49:43Always reminds me of that film Tremors. I don't know if you've seen that, guys. Makes you feel old when you say that. I teach a lot of the younger guys and mention the film Tremors and they, they look at me like I'm mad, they've no idea what I'm talking about. Anyway, there you go.

50:00So, guys, um, that, that is it. Um, I, I really hope you enjoyed it. Thanks for tuning in. I hope it was useful, and in particular, I hope you understood it all and understood the message that I was trying to pro- promote with that. Uh, we need to fully understand the, the dangers around these cables and what will and will and won't protect us from, um, from, from burns. Um, chuck some feedback in the comments, guys. Did you find it useful? Did you learn a few things? Um, hope so. Hope the platform as well worked okay. Um, as I said, there is a bit of a delay, but I'm getting...

50:10that I was trying to promote with that. Uh we need to fully understand the the dangers around these cables and and what will and will not protect us from um from from burns. Um chuck some feedback in the comments, guys. Did you find it useful? Did you learn a few things? Um hope so. Hope the platform as well worked okay. Um as I said, there is a bit of a delay, but I'm getting used to it now, so you kind of pre-empt what's coming up. So, let me know what you thought. Um I've got um

50:34next one's half 11 today, that's getting the best out of the Genny. And then there's um a radio one at um 1:00, I think. Um think today's going to be the last day of the free ones, guys. Um I'm absolutely exhausted. Um we've been doing lots of these and um and trying to manage the company as well, and we're we're getting a bit more paid work coming back in line now, so. So, yeah, tune in later if you want for the other sessions if you've not been.

51:00Yeah, always remember, guys, it's the they're just snippets, these, so you might not fully grasp every concept, and I and I can't help that. We're just just small sections and stuff.

51:20Thanks for the comments, guys. I appreciate it. Makes it worthwhile. As long as you're getting something from it, that's the main thing. And I'm assuming there's no questions, guys, so I'm going to start shutting down this end. Think everyone's leaving now anyway.

51:52Cheers, guys. Okay, I'm going to leave the room now, guys, and the event. So, thanks again. Possibly see you later. Um if not, take care. Stay safe.