Getting the Best From a Genny: Connection, Clamp and Induction

0:15So, so like most transmitters, the um the Genny or the transmitter can be broken down into two main main ways of using it: connection and induction. For any any beginners in here, guys, connection is where, as it says really, you're hooking it up to something. So, we're using direct connection leads or or even a signal clamp. Induction is when we just use the box on its own with nothing connected, and we can sit it on top of a of a buried utility. So, they're the two main ways of using it.

0:44We can we can we can break that down a little bit further as well. Look at the next kind of slide here. We've got direct connection, signal clamp, plug connector, and induction. There's a there's a few other methods as well, but they're the main ones that we that we focus on. So, the the idea with the with the transmitter is that we're sending a signal down the utility to be able to detect it better. Um if you want more information on on why the Genny is so important, watch my power and radio presentation this afternoon. It's called "The Problem with Power and Radio", and we talk a lot about about why it's ineffective to to to be scanning purely in passive modes.

1:20So, what we're doing with a with a with a Genny signal is we're sending a um a current down a down a utility. Um we're creating an electrical circuit which gives off a magnetic field at a particular frequency, and then when we turn our locator on the same frequency to match, we we can detect it. It's and it's the more reliable way of of locating. So, if you look at the top picture on the left here, guys, just to give you a very basic example of of what's happening here, we've got our transmitter, we've hooked up to a metal water pipe, we've placed an earth in the ground, and that is creating a circuit.

1:50So, the idea is the signal's going to travel along here and and back to the earth, and that's our circuit. When I go through the next section, guys, we're going to be talking about signal travel and where it goes. Um just remember, it does actually go both ways. It's an AC circuit, so it's it's actually going both ways. So, for example, with your Genny, you're often told to put your red lead onto your utility and your black lead to ground. You can use it the other way round, guys, if if you want. There's there's no set way of doing it. It's an AC circuit we're applying.

2:15But I will be referring to it as signal travel, and I'll be drawing it out in one direction. So, please please bear that in mind that it is it is kind of going both ways, if you like, on an on an AC circuit. So, that's how our direct connection works. Uh signal clamp, of course, we're just clamping it round the cable. Plug-in adapter, we stick it into a into a socket, and then induction, just above something. So, these are all these are these are all ways of applying a signal onto a buried utility uh to make it more detectable.

2:43What I what I always try and do, and I do this in the training courses that I run as well, what what we try and do with our courses is not only talk about how you operate the kit and and teach people how to operate the kit, what we what we need to try and do is is teach people how to conduct a site survey with it. So, so when the guys get to site and they've got to, you know, they've got an excavation to do and they've got to find everything, give them a format to work to. What do we do first? What do we do next? And again, if you're a utility surveyor, you're probably doing this anyway. You'll you'll be methodical and you'll be working to a process of of locating things in order. Uh but there's no reason why the guys on site can't can't do the same thing when when they're looking for things.

3:20And this is why I often, um if anybody's been on my courses before or talked before, um I often get frustrated with the term "cable avoidance", because cable avoidance, as soon as I hear that word, it it kind of it gives me visions of people walking around in zigzags on on power and radio. And I believe we should talk more about cable location. We can't avoid it till we've located it, and the mindset that we should be in is having this location attitude of going out to deliberately find known services first. So, we always teach guys to start with the Genny, start with the transmitter. That's the first first way that we use the the kit.

3:56So, if we if we look at a typical street scenario then, because I'm sure that's where most people are working, in terms of methodology, what I always recommend to do first, after you've done your visual check and you've looked at your utility plans, is go for the street lighting. It's a really good habit to get into. Let's get the lighting circuit um located first. And and let me give you the reason behind that.

4:17So, we use our transmitter to hook up to the column and put a signal down the cable. Street lighting in the UK works in two different ways, typically. It's what we either call a loop-in loop-out system or a tee'd off system. So, the tee'd off system that you can see on the bottom, um it it basically means that the lighting is fed off the LV main. So, the LV main that goes down the footpath that has branches coming off to all the houses also has branches coming off to the lighting columns. So, as you can see here at the bottom, this is what we call the the tee system.

4:49The the one above it above it is what we call a loop-in loop-out system, and this is where it's usually a separate lighting cable entirely. So, it's separate to the LV main. It's a dedicated lighting cable that goes down that footpath, and if you the reason they call it loop-in loop-out, it kind of goes in and then another one comes out. So, you've kind of got two cables coming out of each column, if that makes sense. That makes sense to everyone, that, guys? You okay with that? So, they're they're the two two variations we have in in the lighting network in the UK. And I'm I'm going to move on to to why we try and do it first, and it's all about trying to save a bit of time, trying to be efficient in in what we're doing on site.

5:27So, if we look at this very basic street scenario that we've got up on on screen now, uh we've got three houses, so naturally, you know, three houses with three service cables, main LV cable, um and and again, this is the attitude that we should have when we're excavating. A lot of guys go out there and think, "Right, I'm digging a hole, I'm going to scan it with my CAT and see if it makes a buzzing noise." What we should be doing is getting to site and saying, "Right, yes, I've got to dig a hole, but what could potentially be in there? There could be an LV main in there, there could be an LV service, there could be a lighting cable in there. So, let's get hooked up and find them. Let's prove where they are first before we start excavating." Okay?

6:04So, going back to this street scenario, let's say I come along to here with that mindset and think, "Right, I need to find all these cables. I'm going to hook my Genny up to each of these buildings, and I'm going to trace all these out, trace the LV main, etc. So, I've got all that traced out. And then, the second thing that I do is I go and hook up to this lighting column, and I suddenly realize that because it's a tee'd system, I've applied a signal onto here, I've got a signal on here, and I've even managed to get a bit of signal on here. Can you see what I've just done there? I've just wasted 20 minutes. If I'd done the lighting first, I'd have found all that."

6:41So, that's the idea of getting into the habit of doing lighting first. I I call it easy street. Some streets you can go into and hook up to the column, and you can find all the LV network off that one connection. Not always though, guys, not always, because, you know, it might be a separate circuit, you you might not get signal to run to these properties depending on the earth at the property. But my point is let's try it first and see what we get. If we hook up to the lighting and we only find the lighting, we've got more work to do, haven't we? Yeah, so we will have to put a bit more time in, but let's see if we can minimize that time. Again, guys, that that makes sense, guys? It's always hard with these webinars because I can't see your faces, so I don't know whether you look confused or asleep. So, at at various sections, guys, I'll be chucking jumping in and asking you just to give me some feedback to let me know you're all still following me um on this, guys. And again, any questions, chuck it in. All right, so that's why we do lighting first.

7:10we can minimize that so. Okay, guys, does that make sense, guys? It's always hard with these webinars because I can't see your faces, so I don't know whether you look confused or asleep. So, I'll at various sections, guys, I'll be jumping in and asking you just to give me some feedback to let me know you're all still following me on this, guys. And again, any questions, chuck it in. All right, so that's why we do lighting first.

7:29Now, let's let's go back a little bit and look how we actually trace street lighting, guys. So, for anyone that hasn't done it before, we hook up to the column. Very simple. So, we get one of our connection leads, fasten it to the metalwork of the column, and put an earth in.

7:45Um, you'll see, especially with the newer kit now, guys, I've not got time to do with a massive amount of detail, but one of the benefits of the new Genny4 is it's sending out what we call simultaneous dual frequency. It's kicking out 33 kilohertz and 131 kilohertz simultaneously. And then when you put your CAT on Genny mode, you guys might have experienced this, you'll get kind of three different noises. When it's cranked up quite high, you'll hear both frequencies coming through. And then as you turn it down, you'll hear either the 33 or the 131.

8:14What that high frequency does, that 131, that enables to do what we call capacitance techniques. And that's where you'll see people wrapping it round a column, guys. You might have seen that before. And it was quite a new thing, so everyone was kind of raving on about it. Yes, it works, but if you've got a metal column, guys, it's not as good as connecting onto it. So, don't automatically go to wrap it round. Get a connection first, and if it doesn't work, wrap it round. Typically, sometimes concrete columns and things, we get it with with wrapping it around, guys.

8:45Okay, so we hook up. Okay, like that. If we can't get an earthing, if it's tarmac or concrete, or flags like this, what we can do is put that pin on the ground like so, and then we can chuck some water on it. There we go, and that gives us an earth.

9:16It doesn't have to be fizzy water, guys. We're just the posh in Wiggin. So, we use sparkling water, but any any liquid will do, and I'll leave you to your imaginations to work out what type of liquids that you could use and have been used in the past. So, that's another way of getting earth, guys, okay? Just by doing that. So, let's go back to to here.

9:36One of the things that I like doing during these sessions, and and I always find it fascinating, is asking people, and I'm going to ask you guys, where do you put the earth in relation to the column? So, do you put it close by? Do you put it far away? What angle do you put it at? How far away does it go? Give me some feedback on that. Because what I tend to find when I ask that question is I get many different answers. There doesn't seem to be any consistency with what people say.

10:07So, where do you think I should put it? Does it matter? Is it just a case of shoving it in anywhere?

10:26As far as possible at 90 degrees. Any other answers there, guys? Close by. So, here we go again. We've got some different ones coming in already. What what is interesting also is if you ask somebody why, they quite often can't tell you. I get answers, "Well, that's the way we've always done it." At 90 degrees and a few meters away, depending on access. So, a variety of different answers. So, we're going to talk in depth now about the earth position. This applies to all transmitters, guys.

10:50Okay. We're going to talk about it, and what I'm going to try and cover with you today is there is no kind of exact right place to put it, but I want to tell you the effects that it that it that it has when you put it in different places. So, I'm not very good at drawing, by the way, guys, so you're going to have to excuse my little diagrams a bit as we as we go through this.

11:18So, let's look at some of the answers there. So, if you imagine I've got my street light column here, and then I get my Genny, so this is obviously a plan view, guys, looking from above. And if I put the earth out here a few meters away or quite far away, would you all accept that that earth wire on the ground now is giving off a massive signal? And it's on the surface of the ground, so it's very close to you, and it's giving off a huge signal like this, yeah? I'm sure you'd all agree with that. So, the the problem with that is then, what what that means is I can't use my locator here. If I go in that area with my locator, I'm going to pick up that earth wire, yeah?

11:59Okay, so how about then, if that's our lighting column, and I clip on the column, put it really close, I can now do a full circle around that column, and it doesn't matter which way that cable goes, I can find it. So, it's actually looking at what you're doing and what you're trying to achieve. You know, I get people asking me, "How close to the column can you work?" And it depends on where you earth it. If I earth it really close, I can get within half a meter of that column, no problem. I can get nice and tight close to it. Okay, so we earth it really, really close.

12:32Where a lot of this has come from, guys, the old the old Mark 1 Gennys, the old handbag Gennys, as they used to call them, they weren't they were nowhere near as good. The impedance matching was nowhere near as good enough, and and you had to get that earth out, you know, quite far away and at 90 degrees just to get signal to run down it. But with these modern transmitters now, guys, they're so good, so effective. The Genny4 is a brilliant transmitter. Um, um, we can now afford to earth it quite close by like that. Okay, and we're going to expand on this point, guys, as we as we go on. So, for now, when we start off, let's let's have it nice and close and be able to work quite close to the column. Does that make sense to everyone, guys? Are you you okay with that?

13:04You can see on here, can you see how close I've got it here? Right at the bottom, so. Really, really, really close.

13:23One of one of the other questions I get asked quite a lot is how far will a Genny signal travel? So, I'm going to ask you guys the same question. How far does a Genny signal travel? Or a transmitter signal. Now, now, bear in mind, guys, you guys that are utility surveyors, you've got multi-frequency transmitters. So, so, frequency affects distance. But remember, we're talking single frequency now. So, just using one single frequency, you know, how far will that will that will that transmitter signal travel? Okay.

13:47Um, and what I'm going to do is there is no set answer, guys. There is no answer to that question. It all depends on so many factors. Let me show you a couple of things here, guys. It's always a fine line with these, guys. I'm trying to share with you as much as I can and not make it too technical and boring. Let's first of all look at the difference between tracing a pipe and tracing a cable in terms of distance. Now, when when I apply this Genny signal onto this column, I'm sure you will all agree that that cable is insulated. Okay? Now, remember, and and it's it's really important to understand this, that that that that signal, if you like, is trying to get back to here, yeah? We're trying to complete the circuit. If anybody watched the, what happens if you hit a cable session with me, we talked about paths of least resistance and stuff on that, do you remember? So, this signal's trying to get to that, but because this cable is insulated, it doesn't get

14:20And it's it's really important to understand this, that that that signal, if you like, is trying to get back to here, yeah? We're trying to complete the circuit. If anybody watched the what happens if you hit a cable session with me, we talked about paths of least resistance and stuff on that, if you remember. So, this signal's trying to get to that, but because this cable is insulated, it doesn't get have an easy time getting off it. So, what it has to do, it has to follow this cable along here, and it's looking for an earth point, yeah? A piece of metal in the ground, which could be another column. What it could be, though, is it could go up here, up here, and then that that LV cable goes into that house, and it's bonded to the metal pipes underneath, yeah? Okay? So, it goes back through ground here, and then back to that earth. Does that make sense, guys, yeah? So, it's it's it's going on the on insulated cable, traveling down it, finding an earth point, and then coming back.

15:13Okay. Now, this is the difference, guys, right? What if that was a metal pipe? What's the difference between a metal pipe and a cable? A metal pipe doesn't have insulation on it, so it's it's metal in contact with ground. So, when we apply a signal to the metal pipe, imagine that's a metal pipe now, can you see that at anywhere along that pipe, that signal can bleed off like this? Yeah.

15:40So, for anyone that's done any tracing, have you ever noticed before, um we do a lot of stuff with the gas lads, and they can they can relate to this really easily. You're tracing a metal gas pipe, metal water pipe, you tend to find that as you're following it, the signal's dying off all the time. You've got to keep nudging your transmitter sensitivity up to compensate for that. When you're tracing a cable, an insulated cable, you tend to find your signal stays a lot more constant, and you can generally travel further um along it. Um and also, think about pipe size. Can you see that a really big pipe has a lot of metal surface area in contact with ground? So, so that signal's going to bleed off really, really quickly compared to a small 2-in pipe. That make sense?

16:19Yeah. You're again, guys, you're all okay with that? Does that make sense? Am I explaining to you the difference between a pipe and a cable and and how signal travels and stuff on it?

16:38Product placement. And of course, guys, on that same subject, if you ever trace the high-pressure gas pipe before, you tend to go really far on them. Why is that? Why can we trace a high-pressure gas, which is a big pipe, is because it's coated. Yeah, high-pressure gas pipes are coated on it, so it's it's like it's like insulated, yeah? It go- it goes further. Okay. Right. So, we've we've we've we keep going backwards and forwards, but remember we're talking about how far a Genny signal will travel, yeah? So, we're still on that same subject. We've talked about the difference between a pipe and a cable. Now, let's go back to the earth position scenario that we talked about. And we said on the lamp column, we'd put it close.

17:21We can afford to do that on a cable because remember what we said, it's insulated, isn't it? So, when that signal hits that cable, it's kind of got to run down it to be able to get off it again, yeah? But with a pipe, it can jump off straight away. So, let me let me draw out what what I'm trying to get at with this. So, imagine that's my metal pipe looking from above, again, plan view. If I get the transmitter and clip here, and put my earth in quite close like I did with the lamp column, what I'm kind of doing there is I'm encouraging my signal to get off early, if you like. That make sense? So, I'm actually not going to trace very far with it um because it's it's it's coming off very quickly. I'm encouraging that to come off. Remember, on a cable, it can't kind of do that because it's insulated. It's going to run down it more.

18:10So, what tends to happen with a with a well, I mean, this is applicable to pipes and cables, guys, don't get me wrong. But from my experience, I found it a bit more dramatic with cables. If I do pull the earth out like this, put it further away, I trace further. Usually, there's a few exceptions, guys, and we haven't got time to go through every different scenario. I'm sure you can appreciate that. Okay? So, that's why we can pull it out. We can start off close and then pull it out, you see. All right?

18:39Now, if you look at the manufacturer's instruction book, and and I'm sure you guys mentioned this, 90°, everyone talks about 90°. Yeah? Um I I tend to not go for 90°. Um and the reason for that is, if you imagine at 90°, I get 50% going this way down the pipe and 50% going that way down the pipe. That make sense? So, you're you're effectively it's going both ways. But you're only tracing one way at once. You've usually only got one locator. So, what what's effectively happening now is half your signal, if you like, is going the wrong way. So, we can adjust it slightly. We can we can bring that earth round to say 45° like this, and we might get 70 going that way. That make sense?

19:21Another thing to consider here as well is if you've if you've got a house up here, with a branch going to it off that, yeah? If you put the earth down here or down here, my signal doesn't want to travel up there. Can you see? It wants to do this. But if I put my earth that way, it now wants to travel up there. But because it wants to travel up here, not as much wants to carry on. So, can you see sometimes it depends on what you're trying to do? Are you trying to trace the main line? Are you trying to pick up the services? What are you trying to do? And where can you put the earth in the best position to help you? This is where we I mean, if you if you um want to come on the high-end EM one on Tuesday, we talk about double-ended connections on there as well. However, guys, there are problems with extending your earth, and I'll give you a real example of this. Okay?

20:13So, let me show you this scenario here. Um we've got this just outside the office, guys. So, we've got a metal water pipe here. And we've also got an electric cable here. So, that's electric, and that's water. We get the transmitter, and we clip on, and we put the earth over here. Now, with any transmitter, what what should happen in theory, on paper, is that whatever you've hooked up to should have a stronger signal on than any return signal. So, what's happening is we've got signal kind of coming along the water pipe, but we've also got another signal on the electric cable. Yeah? Technically speaking, that should have the greater one on it because we're hooked up to it. But we have to take depth into consideration. If this water pipe is 1.5 m deep, and the electric cable is only 500 mm deep, because this one is closer to us, it has the stronger signal. Okay?

21:07Now, for you guys using RD8000s, this is where your current direction comes in and your current measurement comes in, yeah? Your CD feature. If you don't know about CD, guys, um you know, get on the high-end EM one next week. It's a really important feature on the 8000s. But in terms of CAT and Genny, which is what we're talking about, you know, this can be confusing. So, out here, there's a rim of of the valve box, like a metal lid. And what we do instead is we earth to that. So, we get the Genny, one on the valve and one on the earth. And because we're not dragging the earth across here, we don't get this. We manage to then locate the water water pipe. Okay? So, guys, a bit of feed- Does that make sense to everybody, yeah? Do you see what I mean about there is no right or wrong? I'm just trying to show you a bit about the effect that moving that earth has.

21:30is, we earth to that. So we get the Genny, one on the valve and one on the earth. And because we're not dragging the earth across here, we don't get this. We manage to then locate the water water pipe. Okay? So guys, a bit of feedback. Does that make sense to everybody, yeah? Do you see what I mean? Like there is no right or wrong. I'm just trying to show you a bit about the effect that moving that earth around has on stuff. Is everyone all right with that, guys? Any questions on that before I move on to the to the next section?

22:03Excuse me, keep guzzling Pepsi Max, so.

22:12Cool, great stuff, guys. Right. So, we're we're again, we're we're still we keep going off on tangents. We're still on that same theme of of how far a Genny signal will go. So, what we've established so far, I think, is it depends if it's a pipe or a cable. It depends on the earth position, yeah? Let's look at some other factors then now, which we can throw into that.

22:31So, back to this one, guys. Let's look at how a Genny signal travels.

22:42So, if I hook up to this column, I've got a signal on that cable. I'm going to start throwing some questions at you again here, guys. But just for now to get you started, what I would say here is there's 100% on that. It it won't quite be that, but let's just make it easy maths and simple rather than overcomplicating it. And what I'm trying to get at here, guys, is if there was two cables coming out of that column, you'd have 50/50, okay? So, hopefully, you're all with me so far.

23:06That 100% signal is going to get to this joint here, guys. And this is where I want to throw it back at you. What do you think's going to happen here at that point?

23:21Again, sorry about the delay, guys. Just just bear with it. But what do you think's going to happen here? Give me some answers to that, guys.

23:39Yeah. I should have been a bit clearer, guys. Which one? Yeah, Alice has got it bang on. Yeah. It's going to split. How much will it split, though, is what I was getting at, guys. But again, I'm not going to cause any more delay. I'll just get on with it. So, it gets to here, and then we get 50 going that way, and then 50 going that way, yeah?

23:59Now, this, guys, is where we we we need to remember about what this signal's doing, because it won't always split 50/50. Remember what this signal's doing, guys. Electrical current, path of least resistance, best way to ground, yeah? It's looking for a physical ground. So, let's imagine that this cable is fed by a substation here, yeah? Underneath that substation, there's a massive earth mat, and it's quite close by. So, that 100% signal can hit here, and what I might get is 80% going this way and only 20% going that way, okay?

24:34Hopefully, you're with me on that. What I'm trying to get at here, guys, is I can't tell you how much it will split. As as Alice has hit the nail on the head, it depends on the earth going each way. Okay, but hopefully, you can see. I've had it on some places, guys. In fact, out here, it does the same near the sub. You clip on a building, and 100% goes that way, even though it's it is split, the cable, it all goes that way. Now, I know this is technical, guys, but I think it's really important that we understand that, especially for the guys that are excavating, because they need to understand that sometimes it might look like the cable's just bending to the left.

25:04But if they understand this, they'll have that little bit of a doubt and think, "Hang on a minute, is it actually a tee this? Yeah? Is it because of this scenario?" You see, makes sense? So, anyway, we're going to use 50/50 as an example. I'm just going to tidy this screen up a little bit.

25:21Okay, let's go back to my pen. So, we we've got 50 coming this way. And then what's going to happen here? It's going to split, isn't it, guys? Again, this is so important. How much signal is the house going to take? I'm going to throw that back at you. How much signal is that house going to take? You should be able to get this, guys.

25:48If your screen's frozen, Karen, just try hitting the reconnect button. Hopefully, everyone else can still see me.

25:57So, it's it's it's the same, guys, as what Alice has said originally. It depends on the earth. So, one of the things you'll hear me talking about is modern housing and and old housing. And my definition of a modern house is one that's been built with plastic pipes. So, if you hear me say a a modern house, yeah, it could it could be 10 years old, but if it's been built with plastic pipes, I call it a modern house. Modern houses do not usually have a physical ground. They use what's called a PME system. Okay, so there's no physical earth because there's no metal pipes underneath it, okay? So, if this was a modern house with no physical ground, it would take hardly any, if any at all, okay?

26:36If it was an old house with two metal pipes under the ground, might take half of it. If it was a house with one metal pipe, one plastic pipe, it might take a bit of it. Again, can you see where I'm going? I I don't want to overcomplicate it, but we need to understand that there is no set specific amount of signal that will travel down that LV service. It depends on those factors, and every street is different. Okay, but let's keep it simple. Let's say that that does take half my signal, 25. I've got 25% left. It splits again here, 12 and a half, 12 and a half left.

27:08So, when I start getting down to here now, can you see that I'm running out of signal? Yeah? Okay, it's dying off. It's it's running out. So, again, going back to our original question, how far will it travel? Depends how many branches come off it, and it depends if those branches take signal. So, imagine an old terraced street, yeah? They've all got an earth, and they're all very close together. Can you see how you wouldn't trace the LV very far because every branch is taking signal off you? Imagine a big posh street with big mansions spaced far apart, less branches effectively in a in a longer distance, yeah?

27:41You know, on a modern street, you tend to trace further because you don't get any branches taking signal off. Okay, so all this is important. And what's also important on this subject, guys, is is this is why we teach people not to do zigzag scans. We teach people to find the signal and follow it, because can you see what's going to happen when I follow this signal along here? My signal is going to give me a sudden drop there.

28:04And you'll be amazed at how many courses I've been on watching the guys use CAT, and they'll follow a signal along, the signal drops, they just turn the sensitivity control up and carry on. There's no thought process gone in about why that signal might have dropped, do we need to investigate further? So, monitoring signal level and signal drop is a really important part of locating, I believe, of understanding it. Okay.

28:27Again, guys, are you all all okay with that? Chat's gone a bit quiet. You're all still there. Does it all make sense? Anything you want me to expand on or explain in a bit more detail? So, the the Genny's great, but we just have to understand it as well, we need a bit of the science behind it.

28:52Karen, if your screen's frozen, try reconnecting. It must be a connection connection your end. So, guys, let let me just run on to a couple of examples. This is more for the guys

28:54Oh, and if your screen's frozen, try reconnecting. It must be a connection, connection your end. So guys, let me let me just run onto a couple of examples. This is more for the guys that are excavating. Let me let me just explain. I think I think we're get- in the UK now, we're we're getting people to use the Genny more, but sometimes I think that we're we're not doing enough with it, okay?

29:11In other words, I see a lot of guys that are just clipping onto columns. And I and I want to show you some of the things that we need to consider. So, imagine that we've got a a house here like this, a building, and then we've got an LV main and a service connection. And we've got a lamp column here, guys. Again, forgive my rubbish drawing. If we connect our transmitter to this, we've got a 100% signal on that.

29:33And if you remember, guys, it gets to here, 50. Remember, might not always be 50/50, but let's keep it simple. So, 50 goes that way. That house takes 10% of that signal. Yeah, and then I've got 40 left carrying on, okay?

29:49What this means, to try and visualize this, guys, the LV main has got more signal than the service. All right? So, to visualize it, imagine big signal on the LV main, small signal on here. Now, what that means in terms of locating is that we can trace this service, yeah, down to here, okay?

30:11But when we get close to that LV main, it becomes very difficult to determine where it meets it. Does it meet it straight on? Does it go parallel? Does it go diagonal? It's difficult.

30:22So, if my excavation is going to be here, I would argue that's enough because I know that the LV service is not where I'm digging, okay? It's away from me. So, so in terms of accuracy and where it exactly meets the main, not that important.

30:38However, if I was digging here, I would argue that's not enough. We need to get more accuracy on it. So, what we should do, even though we have managed to pick that up off the column, what I would now recommend doing...

30:53Let's imagine now instead, we clip on the house. How much signal do we have here? Yeah, 100%. And then what have we got on the LV main? 50 and 50. Can you see how we've just flipped it?

31:09We had the stronger signal on the LV main and the smaller on the service. We've turned it around now. The bigger signal is on the LV service, the smaller on the LV main. It makes pinpointing where it meets the main much, much easier and much simpler. You'll never get it bang on on a junction anyway, but it makes it far simpler.

31:24And and just to finish off on this point, guys, I don't want to go on about it too much, but I want to just share with you a a cable strike um that happened recently, and I've got many of these examples, but I think it's a good example of how important this is.

31:37The scenario was we had a a house like this, and if you imagine that's the garden wall, driveway, so driveway here and carries on. We had the LV main, and then we had a lamp column here. So, the guys came along, and they clipped onto the column, earthed it, same again, 100%.

31:56Writing backwards there, 100%. 50. And then we've got the LV service doing this. What the LV service actually did is it came down to here, ran parallel, and then went to here. So, we had 50 here, 40 here, and 10 on here.

32:12And what the guys managed to do was they found the service cable on the driveway, they traced it down to here, and what do you think happened? They've got 40 here and 10 there. They basically traced that because this 10 was too close to the 40, you couldn't see the 10. You could you could see it here because nothing else is there, wasn't it?

32:35No, Alistair, it'll go straight down it usually. I'll show you some ways of connecting on. Um, it can sometimes go down go down go down both, Alistair.

32:44Um, does that make sense, guys? Well, if we if we hooked up to the house, how much signal is on here now? We've now got a 100 on the service and only 50 on the main. We could find it bang on. So, it's just to show you how important it is to make that effort to hook up to the house if you can.

33:02Now, obviously, guys, you hear me talking about hooking up to a house. Um, it's amazing how many people don't don't realize how you can do that. Um, you don't need a plug-in plug-in adapter or a plug connector. It's very easy to hook up to somebody's property. Now, I will show you some ways of doing it. So, when you see a building...

33:23If you have a look around that building, you'll be amazed at how many things that you can hook your Genny up to or your transmitter to to find the electric.

33:30So, what we're looking out for is a gas entry point, a gas meter, a tap, an outside light, flue of a boiler, any of these things, hook up to it and you'll usually find the electric service very, very easily, guys. You get such a good signal on it.

33:43Um, so let me just explain in more detail, guys. So, this is a gas entry going into a property. Now, in the UK, we're not allowed to have internal plastic gas in case of a fire, for one very good reason. So, even though it's modern plastic, guys, to a build- modern plastic gas to a building, before it enters and in the house, that has to be metal. So, this bit's metal, this is plastic.

34:06You can see I've earthed with some water. I've hooked up to this. That signal cannot travel back down the plastic gas pipe. The only route for it is to go internally on the metal gas, and what's bonded to the metal gas in the house? You guys might have seen it in your own properties, green and yellow bonding wire passing to your pipes, your taps, sinks. And that goes back to electric cable.

34:27So, it's going down the gas, through the bonding wire, back to your electric meter, and back down the earth wire of the electric cable. So, I know it sounds completely bonkers and backwards, but by clipping on somebody's gas entry, you will get a really good trace on the LV service. But not only that, guys, you'll get a really good trace on the LV main. So, for any of you surveyors that are out there, if you're mapping out the LV main, get onto some nearby buildings and and bang a signal on it, guys. It's so much more effective.

34:54Is everyone okay with that? Makes sense, guys? So, just while you're answering that, I'll just show you a few more. This is an outside gas meter, so we've just clipped onto the inlet here. Again, it's gas, but we're tracing the electric via this method, guys, yeah? If I can't get at that, sometimes I'll just open up the the meter box and clip on the gas meter itself.

35:13Um, outside lights work really well, clip on the the metal outside light. These work brilliantly as well, guys, the little blow-off on a boiler, you can hook up to that. There's loads of ways, guys, loads of ways of putting a signal onto an LV cable if you make a bit of effort to do it.

35:27Taps as well. I use taps as a last resort, guys, because sometimes they don't work because you can have internal plastic, whereas you can't have that um you can't have that with um the gas. So, so loads of ways of hooking up to a house. Let's make the effort to to do that and get a better trace on it.

35:46Uh, who's using CAT4 here, guys? Anybody using CAT4? Um, one of the problems with CAT4, one of the biggest complaints we get about it, uh and and the reason I'm asking is I wan- I wanted to ask if you'd experienced this a bit, is that sometimes when you're on Genny mode, um and you you're trying to adjust sensitivity, um you get what I call quite an erratic response. Um, so you can't see because of my hands. Um, and what do I mean by...

35:50Um, one of the problems with CAT4, one of the biggest complaints we get about it, and, and the reason I'm asking is I want, I wanted to ask if you'd experienced this a bit, is that sometimes when you're on Genny mode, um, and you, you're trying to adjust sensitivity, um, you get what I call quite an erratic response. Um, so, can't, can't see his hands. Um, and what I mean by that is you, you, you turn the sensitivity up a little bit and you tend to get full signal.

36:16You then turn that sensitivity control down a tiny bit and you get none. Has anyone had that before? So, it's kind of all or nothing. It's just like, no, full or, or off. Uh, and, and it's quite common with this kit, but it's a very easy fix. The reason it's doing that usually is because there's too much signal on the utility you're trying to trace. There's too much power on it. And, and what I've found is that over the years, the way people are often trained is, oh, you need a really good signal, you need to get a really good earthing and get a really good dropping tone.

36:43And it's not true, guys. We, we just need enough. We just want enough signal to be able to locate it. When you start banging bucket loads of signals down things, we can cause problems. So, yeah, so that erratic behavior that you've had is too much power. Um, and let me just show you on here, guys. If you just watch what my finger's doing compared to what the display's doing.

37:04You can see I can't get it in the middle. That's down to too much power, too much signal. So, we back it off. We just go to the Genny, and we pull our earth out, backing off our power, yeah? Weakening the signal. And watch the difference now, guys, we can, we can control that really well. Hopefully, you can see that okay, guys.

37:41Did it make sense, guys, that video? Okay with that? There are, um, other benefits, um, to, to hooking up to a building as well. So, so the scenario that you're going to see here, guys, is, um, I've hooked up to a house. I've hooked up to the gas meter to trace the electric. So, if you basically, where I'm stood there now is, if you imagine there's a house here, there's a service cable coming out, then the LV main. And I've hooked up here, guys, yeah, to the house. I am stood, so this CAT here, I'm kind of stood here, yeah, facing that way.

38:16And, and, and what happens is when you, when you, when you've got a 100% signal on, on a cable, and then it splits kind of 50/50 or almost 50/50, you get quite a unique effect that happens on the joints. It's very handy for finding joints, not just on, on, um, on buildings, but on even, even other stuff as well, where you're looking for a tee joint. So, I'm stood here at the moment, and what I always recommend that you do is when you're hooked up to a house, yes, you want to find the service, but I always say let's find the LV main first, just to give us an idea of where that service is going to be fed from. Once you've found that LV main, um, I'll play the video as I talk, guys.

38:52So, here I'm finding the LV main. Remember, this is the section of cable that's got the 50% on it. Once I've found it, I turn the sensitivity control up till I hear both frequencies as a reference point. Then I'll walk along it. You'll hear the signal drop to zero, and then as I go past, it will return. So, I'm going to go back again, and the exact point where that signal stops, that's where the joint is. And as I turn round now, you can see it, and that's the service cable coming down, guys, again. Uh, I hope that makes sense, guys. Just tell me if it didn't, and, um, and, and this is the other thing, guys, you know, this is why we do the practical training. On a normal course, we, we show everyone all this, and then we go outside and get them doing it, and you can see it in, in real life, um, and practice these techniques. But there's nothing stopping you, you know, going out and having a go with this. Uh, what you could do is, you know, book us for some practical training, bit of a sales pitch there.

39:46And that works in most locators as well, that, guys. So, I'm just using CAT4 as an example. You remember at the, at the beginning, guys, um, I touched on the fact that this Genny was kicking out two frequencies, 33 and 131. 131 is very, it's a very high frequency. So, 131 is very good for cables that aren't earthed very well. It's very good at, at jumping gaps, basically. So, we can do a few little neat tricks with it, and they're called capacitance techniques. Um, here we've just held the red wire on somebody's Sky cable from the Sky dish, and that helps us find the electric. Here we've run the cable along, um, a BT cable, that traces the BT, and this is on, on the BT, guys. Again, on these short webinars, I've not got time to go into massive amounts of detail of, of how that works, guys. But this is a BT going into a house, and I'll just show you an easy way we can do this.

40:36Yeah, just hold it on like that. No connection needed, guys. Just, just. Some smart arse always says, well, what if you're on your own? So, on this one, I've sellotaped it. Sellotaped. And just, just watch how well this traces, guys. Yeah, this is a tiny, tiny BT cable. It's the only way of doing it. It's the only way of picking this up.

41:16Okay, lots of little things we can do with it, guys. Um, and then this final one, guys, um, I'm tracing the LV service across the garden. That's the LV. Hear the high pitch, the 131 coming through? And just to show you how I've done this on the CAT, this is, um, a plastic light, guys. You remember with a metal light, you just hook up to it. With a plastic one, we just wrap the lead round it, um, um, three times, and that's enough to get us a signal. So, for you, you guys using high-end locators, RD8000s, vScan, um, vLocs and stuff, you can still do this, but make sure your transmitter's on 131. With, with a Genny, it, it, it's sending out both automatically, guys. So, you can do these capacitance techniques with, with 131 kilohertz.

41:59I'm going to move on to the next section now, guys. Any questions on what we've covered?

42:23Cheers for the, cheers for the recommendations, guys. Appreciate it.

42:33So, what I want to look at now is, now, now we know, um, how to hook up to a building, we can now look at how we apply our signal, um, to, to get a proper survey done. So, this is where plans are really, really important, guys, uh, to help us plan the survey. There's, there's some training provider, providers out there that actually teach the guys to use the CAT and Genny before they look at the plans, but I'm not, I'm not a believer in that. I think they're really important because what we need to start understanding now is where we apply the signal to get the best results.

43:02Okay? So, to give you an example here, guys, this is a Scottish Power drawing. And on Scottish Power, the LV is shown in brown and the, and the HV's red. So, you might not have seen one of these plans, but the principle is the same across all utility plans. And if we look at this area here, guys, you can see we've got two

43:03So, to give you an example here, guys, this is a Scottish Power drawing. And on Scottish Power, the LV's shown in brown and the and the HV's red. So, you might not have seen one of these plans, but the principle is the same across all utility plans. And if we look at this area here, guys, you can see we've got two LV cables and and two HV cables. We're going to ignore the HV for now. If you scan the Oh, if you scan this area on power and radio, you just get one big mess. You can't locate them.

43:25So, we need the Genny. But how do we do it with the Genny? What do we do? Let's concentrate on the two LV. We need to find them both.

43:35So, using the techniques I've just previously shown you, can you see and do you accept that if we hook the Genny onto this building, we're going to get the bulk of the signal on that top cable, and we locate that? If we get the Genny on this building, we're going to locate that bottom one. Makes sense, guys? So, we need to look at our plans, think about where we're applying the signal, okay?

43:57This is a UKPN one down in Kent. Now, this one doesn't show house services, because people say, "Well, our plans don't show house services." They don't need to. You can sometimes see things that are obvious. So, again, this is confusing, guys, for anyone that's new to it, but all these different regions of electric companies use different bloody colors. People look at that and think it's cable TV. It's not. It's two LV cables, like, guys. Power and radio find one. We need to find them both before we excavate. Okay, how do we do it? Let's zoom out.

44:26What we can now see is a split over here. So, where does house 1 get its power from? I'd say this cable. Where does house 14 get its power from? So, even though it doesn't show the house services, I can kind of work it out using a bit of logic. So, if I apply my Genny signal to this house, I'll locate top cable, this house, locate bottom cable. Makes sense, guys?

44:52We could also use the columns here as well. The principles are the same, but the point is let's look at the plans and decide how we're going to go about it. It's also where good quality plans come in as well, guys. Sometimes people give you a really zoomed-in view like that, think they're doing you a favor. But actually, I want to be able to zoom out and have a little look around to see where I'm going.

45:13The other thing that I want to touch on here, guys, and this is more towards again the guys doing excavations, is is the advantages of depth estimations on CATs. A lot of the contractors I do work for, sometimes they, on one I'm thinking of in particular, they don't even let the guys have depth, and I think it's a really important part of it. What we have to understand is that depth isn't just to see how deep something is before we stick a shovel in the ground. It helps us work out what's going on.

45:34So, for example, on this one, what actually happens is when you connect your Genny here, you obviously trace that cable and X marks the spot. When you hook your Genny to this house, you trace this cable, but here, this is kind of where our pretend hole is going to be, yeah? We get the exact same result. It's the exact same place.

45:57So, you could easily think to yourself then, actually, they've branched off. Yeah, we've still got a second cable we're looking for. However, when I was hooked up to this house, I did a depth estimate at this point, and it was 300 mil. And when I was hooked up to this house, I did a depth estimate at that same point, but it was now 600 mil. Can you see what that's telling me? Yeah, I've got both the cables. They're just at different depths on top of each other. So, depth is good for stuff like that. Am I tracing the same thing? You know, if the signals jump, there's loads of reasons for depth, guys, and I think it's important.

46:34Western Power, you can see where I'm going with this, guys. Western Power, blue is LV. Similar thing though, guys. We clip on this house, we trace that one. We clip on this house, and we trace that one. So, this is what I'm trying to get at. Even though we're just doing a small excavation here, we might have a little bit of legwork to do to ensure we get everything.

46:54Do I round depth to the shallowest first? Uh, depends what I'm what I'm doing. I guess, again, I'm not using depth to tell people how deep it is before they dig. So, I'll kind of, you know, give them an idea of it. I'm using it more for my information. I'll give you another example of where depth is good. We clipped on a block of flats a while ago, I always remember this one, with a Genny signal, and we had two signals coming out from.

47:08We knew the gas was plastic, so obviously one was water and one was electric. One of them was about 900 mil deep, and one was 300 mil deep. Which is the water? You get the idea? Um, the the deeper one, you know. So. Okay, hope that makes sense, guys. So, we can, you know, plan our attack.

47:45So, we've we've then got the signal clamp. So, so, if we go back to our our process that we're kind of working to, um, the the idea is the first thing we're going to do is we're going to find all the LV. And that's what we've just covered. We're going to use lighting columns and buildings and whatever else we can, um, to trace the the the LV network. Okay, and that should all be marked out now. And the next thing we're going to do is comms, and we do that with a signal clamp.

48:08So, there's our clamp, and then we just put it around a service. So, this is where we'd lift up a BT lid or a cable TV lid, um, and and clamp round it. Okay, I'm not going to get into the rights and wrongs of lifting these lids, guys. Please refer to your own company procedures. I'm not telling you to do it. I'm just saying that this is how you could do it, um, if you have the right permission to do it. Okay, so we hook up like this and trace the comms. So, we've traced the lighting, we've traced the LV, we've we've traced the comms cables with the with the clamp.

48:39Um, guys, I'm sorry about this, but I've been talking all day and my throat's dry, so I've been drinking lots. I need to go to the toilet. I'm sat here cross-legged. Um, so can we just have a quick 2-minute break? If anybody else wants to run off as well and just, um, go and have a quick toilet break. I won't be 2 minutes. Thank you.

50:50I'm back. Hopefully you're all still there. I've washed my hands. So, that's how we use the signal clamp, guys. BT, it's also for you guys that are out there doing excavations, it's handy in trial holes, this. So, I often tell the teams that if you imagine you're doing a big project down the road, instead of trying to CAT and Genny scan the whole bit, just do a small section and do a trial hole, get the clamp on. And also, if anybody on here is getting utility mapping work done on the sites,

51:25give guys access to cables. So, if you know you've got a team of surveyors coming on and you've got guys on site working, get a few trial holes open for them and they'll then get access to the cables and clamp them and, you know, the more access you give them, the better results that you'll that you'll get with the with the with the final survey drawing and things. So, yeah, that's the clamp, guys. That's how we use it. So, we're going to move on to induction now, guys, and this is where we we drop the box.

51:47I must be really clear on this, guys, that induction is is kind of last resort. We should always try and connect or clamp where we can, and only when we've exhausted all the connection and clamping techniques should we then start pulling induction in. And one of my concerns, guys, and I've seen this first hand, is that because the whole industry is talking about CAT data now and CAT data downloads, a lot of the guys on site are just sticking on induction 10 meters away and leaving it on, just to put figures up, basically. You know, so we need to look out for that. So, once connection and clamp is exhausted, then we start bringing induction in. And the way induction works is that when we disconnect the cables from the Genny,

52:33I'll come back to that, Jez, in a second. We disconnect the cables from the Genny and the dispersal signal comes out. And we sit it on top of a cable, and it induces signal onto it just beneath it. Just going back to Jez's question, I guess the best way to describe it, again, we need a circuit, Jez. So, I'm assuming you're talking about the clamp. So, if the cable's like this, if it's got an earth at each end and you put it on here, we're kind of getting that circuit going on the cable, if you like. But if we have no earth at only one end, we break the circuit. Okay? Hopefully that makes sense. So, that's what the magnetic field look like off the Genny on induction. And the idea is you put it on top of a known service, and it will induce a signal onto whatever's beneath it. Now, guys, again, this is Genny-four specific. Do you remember we talked about how the Genny's putting out two frequencies, 33 and 131?

53:25And you also remember 131 is high frequency. It's better on cables that aren't earthed very well. Okay? And also on that, Jez, as well, just reminding me, if you have got cables that aren't earthed at both ends, sometimes 131 will work on them because it's very high frequency. So, 131's good on comms cables and that kind of stuff. When you're using the Genny on induction, you don't get 131. So, by using it on induction, you're limiting yourself to that single 33 kilohertz. Okay? The other problem of induction, if you see what I'm trying to do here, I'm putting the Genny on top of where I think that BT cable is, and I believe the BT cable is there because of the presence of the BT lid.

54:04Okay? The problem is, in a lot of footpaths, guys, you still don't find the BT. This is an example just outside our office. There is a power cable running parallel with it. The power cable is a better conductor, and more importantly, it's got a better earth on it. So, even though the transmitter is sat above the BT, the signal jumps to that. You're then 10 meters away with your CAT or your locator, and you think you're tracing the BT, and you're not, you're tracing the power again. I have seen so many sites where I've been to do a site visit, and the BT and the power cables are marked in the same place. And as soon as I see that, alarm bells start going off, and I start asking, "How did they find the BT?" And it's usually because they found it in induction. It's not actually the BT they've located.

54:48The way to be sure of getting that BT is by lifting this and clamping it. Not all of the companies like that, guys, do that, though, but we have to accept if we don't go in there and clamp it, sometimes we won't find it, guys. Are you okay with that, guys? Does that make sense? And this isn't just BT, guys. Just remember with induction, it's not selective. You put that in a footpath, it'll go on what it likes best. Okay? Not always on what you stick it directly above. So, hopefully you can see from that why connection and clamping is so important, that we make an effort to do that first. Making sense, guys? You okay? Okay with this section? Cool.

55:28What we what we do do with induction is, this is where the HV comes in now, guys. We spend a lot of time talking about HV on the on the full course, so it's just a few snippets again today, guys. HV is the hardest cable to detect, usually, and that's often surprises people. People think that HV, high voltage, means big signal, and it doesn't. If you've got experience locating, I'm sure you can remember many times where you've picked up a stronger power signal off the LV than you have off the HV. So, we tend to get stronger power signals off LV than we do on HV. And also, think about depth, which is normally deeper. So, the HV's normally deeper than the than the LV cable. So, passive modes are usually not very good finding HV. So, we'll use a Genny. But the problem with a Genny is, where do we hook up to it?

56:16Yeah. Okay. It's usually because of the depth. So, if you imagine in a footpath, Johan is asking about why it's shown on radio. If it was on its own, it would. And it's probably worth just talking about this very, very quickly. People often ask about, you know, why don't if I've got that cable just sat here on its own at a meter, I'm probably going to get it. But if I put another cable in here, I'm probably going to get that one. Does that make sense? Because it's shallower, even if my locator's here. It's picking up like the strongest. If you come on the power and radio on this afternoon, I go into it in a bit more detail, but I always talk talk about it of like throwing things in a pond, yeah?

56:59Imagine, just imagine the signal coming off this HV that's deeper, because it's deeper, as being a pebble. You throw a pebble in a pond, you get a ripple. And imagine this one here that's shallower, stronger signal, being a brick. Drop a pebble and a brick in a pond at the same time. Can you see how you would you wouldn't be able to see the ripple off the pebble because of the brick? That make sense? So, quite often, it's not just it's nothing to do with the cable itself, it's what else is in the ground with it, and you're picking that up instead of. Does that make sense, Johan? I hope I'm pronouncing your name right. If not, sorry. So, so, so, so, it's difficult on passive modes to to to locate it. And we can't connect to it, guys, can we? Most

57:20That make sense? So quite often it's not just, it's nothing to do with the cable itself, it's what else is in the ground with it and you're picking that up instead of. Does that make sense, Shaun? I hope I'm pronouncing your name right. If I'm not, sorry.

57:35So, so, so it's difficult on passive modes to, to, to locate it. And we can't connect to it, guys, can we? Most of us here can't get in subs, we can't, we can't hook up to it. So, so the only way we've got is induction. Yeah? That's the only method we've got of doing it. But we still have that same problem, this scenario here.

57:55We have a HV cable here and we have an LV cable here and we have another cable here. So do you accept that no matter where I put my Genny in this footpath or road, even when it's here, these are nearer. Can you see that? This is very, very common, guys. So, you know, you're trying to induce onto it and you still don't get it because, um, because of the depth angle. Yeah? I don't know if anyone's ever had this before. So that's a problem we have with, with induction as well. So hopefully you can start to see now why

58:18HV is more difficult. So what we try and do is, this is a UKPN drawing again, guys. So if you remember what I said, the green is LV and the red's HV. So imagine that we're going to be excavating here. Yeah? On power and radio, you only find the LV.

58:40No matter where I put that Genny, I only find the LV. Okay? Because again, I've got this, remember? LV's here, HV's down here. Okay, so what we do is we zoom out. Let's take a step back and zoom out. Can you see that when we zoom out, over here, there is a gap between them.

59:00Remember, the reason I can't induce onto that HV is the presence of the LV right near it. But if I hit that HV with some signal here, I can now locate it at my excavation point. Does everyone understand that, guys? Okay? Important point. I know you can't always do this, but my point is if you can, have a look at your plans. Can you find some separation? Can you find a road crossing? Can you find somewhere where it's,

59:20you know, away from the other stuff where you've more chance to hit it with some signal. This is a similar one, guys. This is Western Power, so blue LV, red HV. We're going to excavate here. So obviously we click on the building, we find the LV service and the LV main, then we need to find the HV, yeah? No matter where I put the Genny in this footpath,

59:40I find the LV. So what do I do? I whack it over here. Yeah? Okay. And this is another little tip, guys. Let's do HV last. It's very tempting when you've got a site to think, oh, there's HV there, let's try and find that first.

60:00Yeah, we'll do it last. And the reason for that is simple. If you accidentally induce onto something else by mistake, because you've got everything else already marked, you'll know you are, yeah? So when we're, when we're trying to induce onto the HV, we're trying to look for kind of an odd one out. Yeah? We're coming towards the end now, guys. Don't worry. I know you've been with me for, for a while.

60:20So, so we've, going, going back to our process, guys, we've done our connecting, our clamping, we've done our induction on known services. Uh, we now start to, to finish off with some final sweeps. Has anybody ever heard of a two-man CAT and Genny sweep before or a two-man parallel sweep? Um, just want to get some feedback on that. Have you heard of it before? Um, have you tried it before? Have you been taught to do it before?

61:00Okay, yes and yes, and no's, yeah. Okay. Yeah, Alistair, it's called different things, yeah. Okay, let me, let me just show you, um, why we don't typically recommend doing a two-man, um, CAT and Genny sweep. I want to just show you some of the, some of the problems with it. Um,

61:20let me, let me pull this up because this is still getting taught quite a lot and I just think people need to be aware of its limitations. So for anyone that doesn't know, first of all, going to explain what one is. So imagine that this is our footpath and this is my excavation area. You remember, guys, the CAT and Genny have to be, um, 10 meters apart. Just, just one thing I forgot then, guys, let me just quickly show you something

61:40before I forget again. You should have me in full screen, right, guys? One of the, one of the problems you have with induction, um, with, with the CAT and Genny is that even if that Genny is, is 10 meters away on the floor and I'm here with the CAT, I will still get a signal from it. So in other words, there could be no utility in the ground whatsoever, but I still get a signal from it. And it looks like a real signal. It will peak as I go backwards and forwards through it. Again, you may have had it.

62:00So when you find something on induction mode, what you're going to do is hold the CAT like this, hope you can see this, get, get a signal level, I set it to about the width of my thumb, and then I point the CAT up towards the Genny. And the idea then is that if I raise the CAT and the signal increases, it's coming down right from the transmitter, okay? But if I raise the CAT and the signal decreases, it's coming from an underground utility. So that's a little tip of how we tell the difference between an airborne signal and a real

62:20signal coming from underground. Try it next time you're out, guys. Have a, have a go of it. [sighs]

62:40[no speech] Okay, guys, so back to, back to, uh, our, our, our two-man sweep. So, so the idea of the two-man sweep, as I said, is, let me just get rid of that,

63:00the, the guy with the CAT is here where the excavation's going to be. Sorry. So, footpath, excavation, guy with the CAT here, and the guy with the Genny's here. And they walk across together. So basically, both walk at the same time across the site. And the theory is pretty simple, that if there's a pipe or cable running along that street,

63:20as they go across it, they're going to find it. As the Genny hits it, the CAT hits it at the same time. Hope that makes sense, guys. Now, the problem with that, though, is that if a cable does this, in other words, it changes position between the Genny and the CAT, okay, we're not going to find it. Because when the Genny is here, it's not on the cable, the CAT is,

63:40and then when you walk across together, by the time the Genny is over the cable, the CAT isn't. Does that make sense to everyone? Two-man sweeps are okay for big areas. I would not do them in a, in a footpath, um, or a carriageway, okay? I'm going to show you an alternative. Are, are you okay with that, guys? Makes sense, yeah? See the problems there? So, so instead we do what's called the blind sweep.

64:00Okay? If you look at the picture there, guys, you can see the Genny is in a different position, um, on each, on each one of the, the, the pictures there. Okay, so what we're going to do here, guys, I'm just going to turn the air con on, guys, I'm getting warm here. Um, what we're going to do here is what we call our blind sweep. So let's do the same footpath example.

64:20So this is done at the end, remember, so we'll have a few things marked out. Same footpath, same excavation, and what we do now is we place

64:30...the air con on there, getting warm in here. Um, what we're going to do here is what we call our blind sweep. So let's do the same footpath example. So this is done at the end, remember, so we'll have a few things marked out. Same footpath, same excavation. And what we do now is we place the Genny 10 meters away above the curb, and we scan all the way across the excavation, or all the way across the width for the footpath, or width for the carriage carriageway, yeah? We then place here and scan again, then place here and scan again, then place here and scan again, and place here and scan again. You get the idea?

65:06As long as we scan the whole width of that area on each position, if a cable does do this, can you see we are still going to find it? So I think that personally, that's a better technique than doing the two men together one. It it it's it covers us for any cables that don't run straight, basically, guys. Um, okay.

65:33Yeah, like if you're doing big areas, we've even done it before across rivers with the Environment Agency, I remember us, like across a stream, one on each side of the bank, or on railways and stuff. If you're doing long, long sections, then yeah, two-man sweep, right, but in a footpath, carriageway, where things are a bit more congested and stuff, I think just placing it in each step and and scanning across is a is a little bit better.

65:55So finally, guys, just just moving on, um, what we can now look at is nulling out, okay? Quick go on this. Um, again, we tend to use it towards the end, guys. There's a few reasons why we null out. Um, I haven't got time to cover them all, but I'll give you one example. Let's go back to the HV cable that we talked about. You remember we had the situation where we have the LV here and the HV here? Do you remember that, guys? And and we've just done our little blind sweep, so we've put the Genny in all these positions, but we still haven't found the HV. Yeah?

66:25Because of the shallower cable. So our plans are telling us there's HV there, we know it should be in that footpath, we can't find it, we suspect this is going on. We've looked at our plans and tried to find a point of separation to hit that with some signal, but we can't, according to the plans the cables are running together all the way. So if you look at the signal coming off the transmitter, for those using an 8000, you'll have a little clip on it, I don't know if you've seen that, and it helps it stand on its side like this. So now what we have is that.

66:55Make sense? We got a dead zone here, haven't we? So remember that scenario we had, if we now place that Genny on its side above that LV cable that was shallower, it should get rid of that, but what it should do is light up that one that's off to one side and slightly deeper. So that's why we null out and that's how we null out, guys. Okay?

67:16Guys, there you go. That is how to get the best out of the Genny. Um,