WEBVTT 00:00:00.000 --> 00:00:04.259 You know, we spend so much time obsessing over 00:00:04.259 --> 00:00:06.879 the architecture of our homes, the paint colors, 00:00:07.019 --> 00:00:09.960 the open floor plans, the smart gadgets. But 00:00:09.960 --> 00:00:11.939 we rarely think about the fact that we are living 00:00:11.939 --> 00:00:14.619 inside a machine, a machine with a circulatory 00:00:14.619 --> 00:00:17.460 system that's literally vibrating with lethal 00:00:17.460 --> 00:00:19.980 energy just a few inches from our heads while 00:00:19.980 --> 00:00:22.100 we sleep. Yeah, it's true. We treat the electrical 00:00:22.100 --> 00:00:24.219 grid like it's just, well, magic. You flip a 00:00:24.219 --> 00:00:27.179 switch, light appears. Exactly. But if you actually 00:00:27.179 --> 00:00:31.089 peel back the drywall, What you find isn't magic. 00:00:31.589 --> 00:00:34.850 It is a century -long violent struggle between 00:00:34.850 --> 00:00:37.329 engineering standards and the laws of physics. 00:00:37.560 --> 00:00:40.340 And that is exactly the mission for today's deep 00:00:40.340 --> 00:00:42.420 dive. We're looking at the source material on 00:00:42.420 --> 00:00:45.100 electrical wiring, specifically diving into the 00:00:45.100 --> 00:00:47.600 Wikipedia documentation on its engineering history 00:00:47.600 --> 00:00:49.579 and the physics behind it. Because it's a massive 00:00:49.579 --> 00:00:52.539 topic. It really is. And what struck me immediately 00:00:52.539 --> 00:00:54.340 in the research is that this isn't just a story 00:00:54.340 --> 00:00:56.479 about pulling some copper cables through a wall. 00:00:56.719 --> 00:00:59.240 It is a story about metallurgy, chemistry, and 00:00:59.240 --> 00:01:01.960 frankly, some terrifying trial and error. It 00:01:01.960 --> 00:01:04.540 really is a strict discipline of safety standards. 00:01:04.780 --> 00:01:07.219 When you look at the evolution of wiring, you're 00:01:07.219 --> 00:01:09.379 seeing an industry constantly trying to solve 00:01:09.379 --> 00:01:11.959 three problems at once. Which are? How do we 00:01:11.959 --> 00:01:15.000 move electrons efficiently? How do we stop the 00:01:15.000 --> 00:01:19.319 system from melting down? And how do we keep 00:01:19.319 --> 00:01:21.719 it from killing the people using it? Minor details, 00:01:21.840 --> 00:01:23.319 right. So let's start with the first part of 00:01:23.319 --> 00:01:26.500 that equation, moving the electrons. The material 00:01:26.500 --> 00:01:28.739 itself. Right, the conductors. I think most people 00:01:28.739 --> 00:01:31.079 just assume the wires in their walls are copper. 00:01:31.459 --> 00:01:35.049 And for the most part, today they're right. But 00:01:35.049 --> 00:01:38.109 why copper? Is it just tradition, or is there 00:01:38.109 --> 00:01:40.409 a hard physics reason it became the gold standard? 00:01:40.609 --> 00:01:43.049 It's definitely physics. Copper is sitting in 00:01:43.049 --> 00:01:45.870 a real sweet spot on the periodic table. Obviously, 00:01:45.930 --> 00:01:48.069 silver is a better conductor, but silver is way 00:01:48.069 --> 00:01:50.030 too expensive to put in walls. Yeah, that would 00:01:50.030 --> 00:01:52.390 be a very expensive house. Exactly. Gold doesn't 00:01:52.390 --> 00:01:55.390 corrode, but it's essentially useless for structure 00:01:55.390 --> 00:01:58.790 because it's so soft. Copper gives you high conductivity, 00:01:59.269 --> 00:02:02.329 but more importantly for wiring, it has high 00:02:02.329 --> 00:02:04.959 tensile strength and ductility. Dictility being 00:02:04.959 --> 00:02:07.319 the ability to stretch and bend without snapping. 00:02:07.819 --> 00:02:09.699 Right, because think about the installation process. 00:02:09.919 --> 00:02:12.240 You have to pull these wires through tight spaces, 00:02:12.639 --> 00:02:14.979 bend them hard around corners, twist them into 00:02:14.979 --> 00:02:17.419 terminals. Right, you're wrestling with it. Exactly. 00:02:17.479 --> 00:02:20.680 If the metal is too brittle, it microfractures. 00:02:21.080 --> 00:02:24.599 Copper is incredibly forgiving. It's tough, but 00:02:24.599 --> 00:02:27.340 it's workable. But, and here is where the history 00:02:27.340 --> 00:02:30.460 gets really messy. Copper hasn't always been 00:02:30.460 --> 00:02:33.870 the only option. The source material highlights 00:02:33.870 --> 00:02:37.449 a period in the late 1960s and mid 70s where 00:02:37.449 --> 00:02:40.250 the industry made a massive pivot Oh, yeah, the 00:02:40.250 --> 00:02:43.469 aluminum era is a classic case of economics driving 00:02:43.469 --> 00:02:46.250 engineering and arguably doing it way too fast 00:02:46.250 --> 00:02:49.229 in the mid 60s Copper prices just went vertical 00:02:49.229 --> 00:02:51.509 because of supply chain shortages and strikes, 00:02:51.509 --> 00:02:53.689 right? Yes strikes in major copper producing 00:02:53.689 --> 00:02:56.449 countries So builders are looking at their spreadsheets 00:02:56.449 --> 00:02:58.990 seeing the cost of wiring a suburban home tripling 00:02:58.990 --> 00:03:02.180 and they desperately look for a substitute And 00:03:02.180 --> 00:03:04.400 to aluminum? On paper, it looked like a total 00:03:04.400 --> 00:03:06.759 savior. Aluminum is abundant, it's cheap, and 00:03:06.759 --> 00:03:08.780 it's lightweight. You could just use a thicker 00:03:08.780 --> 00:03:11.240 gauge of aluminum to match the conductivity of 00:03:11.240 --> 00:03:13.819 copper and still save a lot of money. But as 00:03:13.819 --> 00:03:15.900 anyone who has bought a house from the 1970s 00:03:15.900 --> 00:03:19.419 knows, this didn't go smoothly. The sources describe 00:03:19.419 --> 00:03:22.340 a literal wave of house fires attributed to these 00:03:22.340 --> 00:03:26.620 connections. But I want to dig into why. Because 00:03:26.620 --> 00:03:28.599 it wasn't that the aluminum couldn't carry the 00:03:28.599 --> 00:03:31.120 current. Correct. The wire itself was totally 00:03:31.120 --> 00:03:33.419 fine. The failure happened at the connection 00:03:33.419 --> 00:03:36.699 points, the outlets, the switches, the splices. 00:03:36.740 --> 00:03:39.360 Where it met the hardware. Yes. It comes down 00:03:39.360 --> 00:03:42.780 to two specific physical properties where aluminum 00:03:42.780 --> 00:03:46.199 differs from copper. The first is its coefficient 00:03:46.199 --> 00:03:48.460 of thermal expansion. Meaning how much the metal 00:03:48.460 --> 00:03:50.379 expands when it gets hot and shrinks when it 00:03:50.379 --> 00:03:52.520 cools down? Precisely. Every time you turn on 00:03:52.520 --> 00:03:54.699 a vacuum cleaner or space heater, current flows, 00:03:55.400 --> 00:03:57.599 and that wire heats up. Which is normal. Totally 00:03:57.599 --> 00:04:00.180 normal, but... Aluminum expands significantly 00:04:00.180 --> 00:04:03.080 more than copper does under the same load. Then 00:04:03.080 --> 00:04:05.620 you turn the appliance off, and it shrinks. So 00:04:05.620 --> 00:04:08.020 the wire is effectively breathing inside the 00:04:08.020 --> 00:04:10.520 screw terminal. Yes. Expanding and contracting 00:04:10.520 --> 00:04:13.099 over and over again. And eventually, this mechanical 00:04:13.099 --> 00:04:16.019 pumping action works the screw loose. But that 00:04:16.019 --> 00:04:17.800 leads to the second problem, which is creep. 00:04:18.199 --> 00:04:20.540 Which sounds like a horror movie title, but in 00:04:20.540 --> 00:04:23.139 metallurgy, that's cold flow, permanent deformation, 00:04:23.319 --> 00:04:25.839 right? Right. Aluminum is a softer metal. When 00:04:25.839 --> 00:04:28.720 you tighten a screw down on it, over time, the 00:04:28.720 --> 00:04:30.560 metal essentially flows away from that pressure 00:04:30.560 --> 00:04:32.980 point to relieve the stress. It flattens out 00:04:32.980 --> 00:04:35.379 permanently. So now you have a gap. And a gap 00:04:35.379 --> 00:04:37.740 means high resistance. And high resistance means 00:04:37.740 --> 00:04:41.379 heat. Exactly. And it gets even worse. Once that 00:04:41.379 --> 00:04:44.120 gap opens up, you invite in the third enemy, 00:04:44.600 --> 00:04:46.779 which is galvanic corrosion. For battery effect. 00:04:47.040 --> 00:04:50.000 Yes. Most electrical terminals in the 60s were 00:04:50.000 --> 00:04:53.120 made of brass or steel, metals designed for copper. 00:04:53.769 --> 00:04:56.250 When you put aluminum against a dissimilar metal 00:04:56.250 --> 00:04:58.470 and add just a little humidity from the air, 00:04:58.990 --> 00:05:01.689 you create a microscopic battery. The aluminum 00:05:01.689 --> 00:05:04.529 starts to corrode. And unlike copper rust, which 00:05:04.529 --> 00:05:07.670 is conductive, aluminum oxide is actually a ceramic. 00:05:07.810 --> 00:05:10.230 It's an insulator. That is the critical failure 00:05:10.230 --> 00:05:12.889 point. You have a loose connection due to thermal 00:05:12.889 --> 00:05:15.790 expansion and creep, and now the contact point 00:05:15.790 --> 00:05:18.290 is coating itself in a layer of non -conductive 00:05:18.290 --> 00:05:20.629 ceramic dust. So the electricity is trapped. 00:05:20.920 --> 00:05:23.319 Right, it has to arc to jump the gap. And that 00:05:23.319 --> 00:05:25.839 arc is roughly 5 ,000 degrees Fahrenheit. And 00:05:25.839 --> 00:05:28.639 there goes the house. It is fascinating that 00:05:28.639 --> 00:05:30.939 a mismatch in thermal expansion coefficients 00:05:30.939 --> 00:05:34.220 can literally burn a neighborhood down. It is. 00:05:34.360 --> 00:05:36.680 Now, we fixed this eventually. We developed new 00:05:36.680 --> 00:05:39.379 alloys in the late 70s that act more like copper. 00:05:39.740 --> 00:05:42.660 And we introduced these COAL -R rated devices. 00:05:42.839 --> 00:05:45.160 Those are the switches and outlets specifically 00:05:45.160 --> 00:05:48.180 designed for aluminum. Exactly. They use indium 00:05:48.180 --> 00:05:51.160 or special geometries to maintain contact even 00:05:51.160 --> 00:05:53.660 if the wire changes shape. And what about the 00:05:53.660 --> 00:05:55.939 antioxidant paste, the purple goo you sometimes 00:05:55.939 --> 00:05:58.350 see? Yeah, the paste. sometimes with zinc dust 00:05:58.350 --> 00:06:01.329 in it, that's to stop the oxygen from hitting 00:06:01.329 --> 00:06:03.730 the metal and creating that ceramic layer. It 00:06:03.730 --> 00:06:06.050 breaks up the oxide. It's basically a chemical 00:06:06.050 --> 00:06:08.170 patch for physical vulnerability. But honestly, 00:06:08.350 --> 00:06:10.649 for residential branch wiring, like the small 00:06:10.649 --> 00:06:12.990 stuff in your bedroom, we mostly just went back 00:06:12.990 --> 00:06:15.370 to copper, right? We did. It's just safer and 00:06:15.370 --> 00:06:17.509 requires less specialized knowledge to install 00:06:17.509 --> 00:06:20.310 correctly. But aluminum is still king in the 00:06:20.310 --> 00:06:22.350 larger infrastructure, like the service lines 00:06:22.350 --> 00:06:24.759 coming into the house from the street. Oh, absolutely. 00:06:25.420 --> 00:06:27.579 For heavy power transmission lines and service 00:06:27.579 --> 00:06:30.439 entrance cables, aluminum is really the only 00:06:30.439 --> 00:06:32.899 logical choice because of the weight. Copper 00:06:32.899 --> 00:06:34.699 would just be too heavy to string up on poles. 00:06:34.920 --> 00:06:37.579 Way too heavy and way too expensive. But those 00:06:37.579 --> 00:06:40.100 aluminum connections are massive lugs. They're 00:06:40.100 --> 00:06:42.420 torqued down with wrenches, often checked by 00:06:42.420 --> 00:06:45.319 professionals. It is a completely different environment 00:06:45.319 --> 00:06:48.800 than a 15 -amp outlet behind your sofa. Speaking 00:06:48.800 --> 00:06:51.019 of environments, let's pivot to the infrastructure 00:06:51.019 --> 00:06:54.279 itself. Because the wire doesn't just float in 00:06:54.279 --> 00:06:57.360 space. The outline highlights a few different 00:06:57.360 --> 00:07:00.199 methods of routing, specifically raceways. But 00:07:00.199 --> 00:07:02.699 first, let's talk about standard wiring. Sure. 00:07:02.879 --> 00:07:05.500 The stuff we see every day. In a standard home, 00:07:05.680 --> 00:07:08.120 we are used to thermoplastic sheathed cable, 00:07:08.600 --> 00:07:10.879 often with a splash of color, like the green 00:07:10.879 --> 00:07:13.160 or yellow stripes you see for earth and grounding 00:07:13.160 --> 00:07:15.519 in the UK and other jurisdictions. Right. It's 00:07:15.519 --> 00:07:18.120 flexible, plastic -wrapped. and we snake it through 00:07:18.120 --> 00:07:20.800 hollow walls. It's fast and cheap. But if you 00:07:20.800 --> 00:07:23.819 walk into a factory or a steel mill, you won't 00:07:23.819 --> 00:07:26.240 see that plastic wrapping. No, in industrial 00:07:26.240 --> 00:07:28.399 settings where you're dealing with extreme heat 00:07:28.399 --> 00:07:31.339 or physical danger, that plastic melts or gets 00:07:31.339 --> 00:07:34.509 crushed. So what do they use? The source material 00:07:34.509 --> 00:07:38.350 mentions mineral insulated cable, and the description 00:07:38.350 --> 00:07:40.529 of this fascinated me because it sounds more 00:07:40.529 --> 00:07:43.269 like blacksmithing than electrical work. It is 00:07:43.269 --> 00:07:45.730 a remarkable manufacturing process. You start 00:07:45.730 --> 00:07:48.790 with a giant copper tube. You insert heavy copper 00:07:48.790 --> 00:07:51.029 rods inside it, and those are your conductors. 00:07:51.029 --> 00:07:53.529 Okay. Then you fill the empty space with magnesium 00:07:53.529 --> 00:07:55.970 oxide powder. Which is essentially a ceramic. 00:07:56.230 --> 00:07:59.850 Yes, and highly fire resistant. Then... And this 00:07:59.850 --> 00:08:02.769 is the crazy part. They run this entire assembly 00:08:02.769 --> 00:08:06.329 through rollers and dyes to stretch it out. It 00:08:06.329 --> 00:08:09.189 compresses the tube, crushing that powder until 00:08:09.189 --> 00:08:11.689 it becomes solid, literally like a rock. So the 00:08:11.689 --> 00:08:14.529 final product is a solid copper sheath. with 00:08:14.529 --> 00:08:17.470 rock hard insulation inside, holding the wires 00:08:17.470 --> 00:08:20.370 rigidly in place. It is incredibly tough. You 00:08:20.370 --> 00:08:21.910 can hit it with a hammer, you can run through 00:08:21.910 --> 00:08:24.029 a fire, and it will not short out. It acts more 00:08:24.029 --> 00:08:26.910 like a pipe. But it is miserable to install. 00:08:27.129 --> 00:08:29.189 Because it's so stiff. Yeah, you don't pull it. 00:08:29.230 --> 00:08:31.089 You wrestle it into place. But the trade off 00:08:31.089 --> 00:08:33.909 is invincibility. Pretty much. Then there is 00:08:33.909 --> 00:08:38.059 the marine environment. Wiring on ships. Saltwater 00:08:38.059 --> 00:08:40.360 is obviously the enemy of all things electrical, 00:08:40.779 --> 00:08:43.299 but the notes mention that it's not just corrosion 00:08:43.299 --> 00:08:46.379 they're worried about. It's containment. That's 00:08:46.379 --> 00:08:49.620 a critical distinction. A ship is a series of 00:08:49.620 --> 00:08:52.899 watertight compartments. If you drill a hole 00:08:52.899 --> 00:08:55.759 through a bulkhead to run a wire and that compartment 00:08:55.759 --> 00:08:58.879 floods, that wire potentially becomes a leak 00:08:58.879 --> 00:09:01.039 path. Wait, the water could travel along the 00:09:01.039 --> 00:09:03.539 wire? Or even inside the cable jacket itself, 00:09:03.779 --> 00:09:06.399 between the strands, acting like a hose. I didn't 00:09:06.399 --> 00:09:09.080 even think about that. Yeah. So marine cable 00:09:09.080 --> 00:09:12.820 requires blocking compounds to stop water ingress. 00:09:13.279 --> 00:09:15.659 And where it passes through walls, they use stuffing 00:09:15.659 --> 00:09:18.379 tubes or multi -cable transits. What are those? 00:09:18.480 --> 00:09:20.620 They're high compression rubber blocks that squeeze 00:09:20.620 --> 00:09:23.299 the cable so tightly that water cannot pass, 00:09:23.559 --> 00:09:25.899 even under immense pressure. And the wire itself, 00:09:25.940 --> 00:09:28.259 they modify the copper for ships, right? Yes, 00:09:28.259 --> 00:09:31.090 they use tinned copper wire strands. Every single 00:09:31.090 --> 00:09:33.269 strand is coated in tin. Tin is slightly less 00:09:33.269 --> 00:09:36.289 conductive than bare copper, but it resists corrosion 00:09:36.289 --> 00:09:38.549 much better. It acts as a sacrificial layer. 00:09:39.029 --> 00:09:42.190 Exactly. If salt air gets in, the tin oxidizes. 00:09:42.610 --> 00:09:45.570 But the copper underneath remains intact to carry 00:09:45.570 --> 00:09:48.490 the current. Add a thick, rugged jacket on top 00:09:48.490 --> 00:09:51.210 of that, and it can survive the ocean. So we've 00:09:51.210 --> 00:09:53.409 talked about residential and extreme environments. 00:09:53.809 --> 00:09:56.570 Let's look at how we move massive amounts of 00:09:56.570 --> 00:09:59.700 power. The sources mention bus bars. Right. First 00:09:59.700 --> 00:10:02.879 of all, why the term bus? It's actually a contraction 00:10:02.879 --> 00:10:05.879 of the Latin word omnibus, meaning for all. It's 00:10:05.879 --> 00:10:08.259 the main trunk that serves everyone. Ah, that 00:10:08.259 --> 00:10:11.139 makes sense. So what is a bus bar exactly? When 00:10:11.139 --> 00:10:13.759 you need to move thousands of amps, say, in a 00:10:13.759 --> 00:10:16.700 data center or a large building, a flexible cable 00:10:16.700 --> 00:10:18.879 would need to be the size of a tree trunk. It 00:10:18.879 --> 00:10:20.559 becomes totally unmanageable. So they switch 00:10:20.559 --> 00:10:24.309 to solid metal. Correct. A bus bar is a solid, 00:10:24.570 --> 00:10:27.970 rigid strip of copper or aluminum. It's not insulated 00:10:27.970 --> 00:10:30.009 in the traditional sense. It's usually suspended 00:10:30.009 --> 00:10:33.009 on ceramic or plastic standoffs to let the air 00:10:33.009 --> 00:10:35.750 cool it. Because at that amperage, the heat generation 00:10:35.750 --> 00:10:38.850 is massive. Exactly. A rubber jacket would just 00:10:38.850 --> 00:10:42.970 melt and trap all that heat. By leaving it bare, 00:10:43.230 --> 00:10:45.570 but obviously protected inside a locked cabinet, 00:10:46.029 --> 00:10:47.830 the air can circulate and keep the operating 00:10:47.830 --> 00:10:49.970 temperature down. It's very brute force engineering. 00:10:50.210 --> 00:10:51.950 And for the smaller stuff in commercial buildings, 00:10:52.230 --> 00:10:56.590 we use raceways, conduits, trays. Yes. In an 00:10:56.590 --> 00:10:58.590 office building, you'll see wires pulled through 00:10:58.590 --> 00:11:01.730 rigid steel conduits. It offers physical protection 00:11:01.730 --> 00:11:04.049 and acts as a secondary ground. And the source 00:11:04.049 --> 00:11:06.389 is also mentioned chasing grooves into masonry. 00:11:06.519 --> 00:11:08.620 which is very common in Europe. They don't have 00:11:08.620 --> 00:11:11.860 hollow drywall like in America. They have solid 00:11:11.860 --> 00:11:14.620 brick walls. So they literally carve a groove 00:11:14.620 --> 00:11:17.620 into the brick, lay the cable, and plaster over 00:11:17.620 --> 00:11:19.919 it. That sounds like a nightmare for renovation. 00:11:20.200 --> 00:11:21.659 Oh, it is. You're basically doing demolition 00:11:21.659 --> 00:11:23.600 just to move a light switch. Now, it's amazing 00:11:23.600 --> 00:11:25.899 how much engineering goes into protecting these 00:11:25.899 --> 00:11:28.600 wires from heat, water, and physical damage. 00:11:29.179 --> 00:11:31.539 But sometimes the enemy isn't chemical or physical. 00:11:31.940 --> 00:11:34.840 Sometimes it's biological. Oh, the rodents. This 00:11:34.840 --> 00:11:36.539 part of the research gave me a good laugh, but 00:11:36.539 --> 00:11:38.779 it's actually a huge problem for the electrical 00:11:38.779 --> 00:11:42.679 grid. Why are squirrels and rats so obsessed 00:11:42.679 --> 00:11:45.759 with our power lines? It is a massive issue. 00:11:46.159 --> 00:11:48.440 There's this persistent myth that the insulation 00:11:48.440 --> 00:11:51.500 is made of plant -based plastics and that the 00:11:51.500 --> 00:11:53.320 animals find it tasty. I've definitely heard 00:11:53.320 --> 00:11:56.120 that, like the eco -friendly wiring theory. While 00:11:56.120 --> 00:12:00.139 some modern plastics do use biocomponents, the 00:12:00.139 --> 00:12:02.720 actual biological data suggests it's much simpler. 00:12:03.569 --> 00:12:06.350 Rodents have teeth that never stop growing. Right. 00:12:06.429 --> 00:12:08.610 They have a biological imperative to gnaw on 00:12:08.610 --> 00:12:11.370 things, to sharpen them and keep them at a manageable 00:12:11.370 --> 00:12:14.549 length. So a PVC cable is just the right consistency? 00:12:14.669 --> 00:12:17.230 It's perfect. It's firm but chewy. It's basically 00:12:17.230 --> 00:12:19.570 a teething ring for rats. The problem is when 00:12:19.570 --> 00:12:21.330 they gnaw through the jacket of a high -voltage 00:12:21.330 --> 00:12:23.710 line, it usually ends poorly for the squirrel, 00:12:24.070 --> 00:12:26.169 but it also trips the transformer and knocks 00:12:26.169 --> 00:12:27.909 out power for the whole neighborhood. Or in a 00:12:27.909 --> 00:12:29.970 home, they chew the neutral wire and cause a 00:12:29.970 --> 00:12:32.759 fire hazard. Exactly. Telephone and network cables 00:12:32.759 --> 00:12:35.179 get hit hard, too. So the industry had to fight 00:12:35.179 --> 00:12:38.240 biology. How do you stop a determined rat? Well, 00:12:38.299 --> 00:12:40.120 in high -risk areas, they use armored cable, 00:12:40.580 --> 00:12:43.279 wires wrapped in a spiral of steel. But there's 00:12:43.279 --> 00:12:45.879 also a chemical solution, insulation loaded with 00:12:45.879 --> 00:12:49.820 pepper dust. The spicy cables. Exactly. Manufacturers 00:12:49.820 --> 00:12:52.440 can embed capsaicin, the same compound that makes 00:12:52.440 --> 00:12:54.879 chili peppers hot, into the plastic jacket of 00:12:54.879 --> 00:12:57.299 the cable. So the rat takes one bite and gets 00:12:57.299 --> 00:12:58.940 the equivalent of a mouthful of ghost pepper. 00:12:59.200 --> 00:13:02.179 That is the idea. It creates a severe burning 00:13:02.179 --> 00:13:05.240 sensation that discourages a second bite. It's 00:13:05.240 --> 00:13:08.460 a very elegant, non -lethal way to say keep out. 00:13:08.639 --> 00:13:10.960 I love that we are literally using culinary science 00:13:10.960 --> 00:13:13.220 to protect the power grid. Whatever works, right. 00:13:13.500 --> 00:13:15.460 Let's step back in time for a moment because 00:13:15.460 --> 00:13:17.580 we've been talking about all these advanced protections, 00:13:18.100 --> 00:13:20.840 grounded conduits, spicy jackets, mineral insulation, 00:13:21.240 --> 00:13:23.539 but the history of residential wiring is, well, 00:13:23.659 --> 00:13:25.620 it's frightening. Frightening is a very fair 00:13:25.620 --> 00:13:28.539 word. If you look at the Wild West era of wiring, 00:13:29.080 --> 00:13:33.200 from roughly the 1880s to the 1930s, the philosophy 00:13:33.200 --> 00:13:35.799 was completely different. Describe the knob and 00:13:35.799 --> 00:13:37.679 tube setup for us, because I've seen it in older 00:13:37.679 --> 00:13:39.659 attics and it looks like a chaotic spider web. 00:13:40.019 --> 00:13:42.720 It really does. It consisted of single conductors 00:13:42.720 --> 00:13:45.019 suspended on ceramic knobs and passing through 00:13:45.019 --> 00:13:46.620 ceramic tubes whenever they had to go through 00:13:46.620 --> 00:13:48.799 a wooden joist. And the insulation on the wire 00:13:48.799 --> 00:13:51.240 itself. It was usually just cotton cloth soaked 00:13:51.240 --> 00:13:54.659 in asphalt or rubber. But here's the key. The 00:13:54.659 --> 00:13:57.820 real insulation was the air. They relied on the 00:13:57.820 --> 00:14:00.379 fact that the wires were spaced out and air could 00:14:00.379 --> 00:14:02.279 circulate around them to dissipate the heat. 00:14:02.519 --> 00:14:04.500 Which works fine until you decide to renovate 00:14:04.500 --> 00:14:07.879 your 1920s Victorian home and blow modern insulation 00:14:07.879 --> 00:14:10.759 into the walls. Precisely. This is the tragedy 00:14:10.759 --> 00:14:13.519 of Nob and Tube. It was actually a fairly safe 00:14:13.519 --> 00:14:16.779 system for its time. But as soon as we started 00:14:16.779 --> 00:14:19.659 packing our walls with fiberglass, we surrounded 00:14:19.659 --> 00:14:22.159 those wires. They couldn't shed heat anymore. 00:14:22.340 --> 00:14:24.600 So they cooked. They cooked. And then that old 00:14:24.600 --> 00:14:26.759 rubber insulation. It had sulfur in it for the 00:14:26.759 --> 00:14:29.019 vulcanization process. And sulfur attacks copper? 00:14:29.580 --> 00:14:31.919 Right. It forced them to tin the copper just 00:14:31.919 --> 00:14:34.440 to protect it from its own inflation. But over 00:14:34.440 --> 00:14:37.039 decades, that rubber becomes brittle and flakes 00:14:37.039 --> 00:14:39.820 off just by touching it. Leaving bare energized 00:14:39.820 --> 00:14:43.220 wires hidden in your walls. Exactly. A chemistry 00:14:43.220 --> 00:14:46.580 problem that we didn't fully solve until modern 00:14:46.580 --> 00:14:49.750 plastics like PVC and nylon came along. But the 00:14:49.750 --> 00:14:52.009 source material lists some early methods that 00:14:52.009 --> 00:14:55.809 sound even worse than knob and tube. The dangerous 00:14:55.809 --> 00:14:58.309 creativity of the early days. Oh, the transition 00:14:58.309 --> 00:15:01.129 period. Before standard conduits, people were 00:15:01.129 --> 00:15:03.629 just improvising. The one that always chills 00:15:03.629 --> 00:15:06.870 me is running wires through old gas pipes. Because 00:15:06.870 --> 00:15:09.250 homes used to have gas lighting before electricity. 00:15:09.409 --> 00:15:11.309 Right, so the pipes were already in the walls. 00:15:11.990 --> 00:15:14.610 Installers thought, hey, a ready -made raceway. 00:15:15.009 --> 00:15:17.409 They push electric wires right through the iron 00:15:17.409 --> 00:15:20.350 gas pipes. But iron pipe threads have sharp edges. 00:15:20.610 --> 00:15:23.049 Razor sharp. You pull the wire, you strip the 00:15:23.049 --> 00:15:25.730 insulation right off, and you energize the entire 00:15:25.730 --> 00:15:27.950 gas pipe network of the house. That sounds like 00:15:27.950 --> 00:15:30.389 a bomb waiting to go off. And there was also 00:15:30.389 --> 00:15:32.730 a mention of burying wires in wooden troughs 00:15:32.730 --> 00:15:35.070 filled with pitch. Yes, and embedding rubber 00:15:35.070 --> 00:15:37.690 tubes in wet plaster, then pulling them out to 00:15:37.690 --> 00:15:40.250 leave a cavity for the wire. Just a tunnel in 00:15:40.250 --> 00:15:42.570 the plaster with no protection. It really seems 00:15:42.570 --> 00:15:45.330 like for the first 50 years we were just throwing 00:15:45.330 --> 00:15:47.610 things at the wall to see what didn't catch fire. 00:15:47.820 --> 00:15:50.399 It was a steep learning curve paid for in property 00:15:50.399 --> 00:15:52.879 damage. Which brings us to today. We have strip 00:15:52.879 --> 00:15:55.279 codes, we have flame retardant plastics, we have 00:15:55.279 --> 00:15:58.519 spicy cables. As we synthesize all this, what 00:15:58.519 --> 00:16:00.639 is the big takeaway for you from all these sources? 00:16:01.200 --> 00:16:03.500 I think it's the realization that electrical 00:16:03.500 --> 00:16:07.460 wiring is a constant, delicate balance. You're 00:16:07.460 --> 00:16:10.220 balancing material costs like copper versus aluminum 00:16:10.220 --> 00:16:12.720 against environmental demands, whether that's 00:16:12.720 --> 00:16:16.419 heat, moisture or rats. And above all, safety. 00:16:16.720 --> 00:16:19.360 It's a system designed to contain a very dangerous 00:16:19.360 --> 00:16:22.360 force. Exactly. It's not just wire. It's an engineered 00:16:22.360 --> 00:16:24.899 containment field. That is such a great way to 00:16:24.899 --> 00:16:27.259 look at it. And for you listening, I really encourage 00:16:27.259 --> 00:16:29.700 you to just look at a simple power outlet in 00:16:29.700 --> 00:16:32.360 your room today. Realize that it's just the terminal 00:16:32.360 --> 00:16:35.580 point of a massive, historically complex system 00:16:35.580 --> 00:16:38.720 involving geology, chemistry, and over a century 00:16:38.720 --> 00:16:40.799 of engineering. It really puts it in perspective. 00:16:41.120 --> 00:16:42.919 And I'll leave you with one final thought. We 00:16:42.919 --> 00:16:44.720 talked about how we move from dangerous open 00:16:44.720 --> 00:16:47.779 wires to plastic sheath safety. But our built 00:16:47.779 --> 00:16:51.230 environment is a patchwork. With those aluminum 00:16:51.230 --> 00:16:54.330 connections from the 70s still slowly loosening 00:16:54.330 --> 00:16:57.429 inside walls and that sulfur -heavy rubber insulation 00:16:57.429 --> 00:17:00.529 crumbling in older historic homes, how much of 00:17:00.529 --> 00:17:03.009 our built environment is silently ticking toward 00:17:03.009 --> 00:17:06.130 a mandatory, highly invasive overhaul? We are 00:17:06.130 --> 00:17:08.609 running modern lives on some very old infrastructure. 00:17:08.940 --> 00:17:11.640 That is a genuinely provocative thought to end 00:17:11.640 --> 00:17:13.579 on. I'm definitely going to go check the date 00:17:13.579 --> 00:17:15.960 on my circuit breaker panel. Always a good idea. 00:17:16.079 --> 00:17:17.839 This has been an incredibly illuminating look 00:17:17.839 --> 00:17:19.740 behind the drywall. Thanks for diving into the 00:17:19.740 --> 00:17:21.900 sources with us. My pleasure. And thanks to you 00:17:21.900 --> 00:17:23.619 for joining us on this deep dive. We'll catch 00:17:23.619 --> 00:17:24.319 you on the next one.