Ducks on thermal camera

J Sigmo

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Many years ago, a guy brought a thermal imaging camera into the place where I worked. He was somewhat desperate because he had connected it backwards to a big 12V battery, and fried it. This was an AGA "Thermovision" thermoscan camera back in the late 1970s, or early 1980s.

I got the job of troubleshooting it for the poor guy. It turned out that it had only damaged one bipolar transistor, But it was somewhat odd finding it because this was the one and only bad bipolar transistor I have ever run across in 45 years of electronics work that was bad, yet measured as if it was good on a multimeter using the simple "diode test" function. You'd think that there would be all sorts of transistor failures that wouldn't show up with such a crude way of testing them, but that remains the one and only example I've ever seen!

Anyhow, we had a suitable replacement transistor, and I got it fixed fairly quickly. But then I had to play with the thing!

This was a rather miraculous device for the day. It used a single photodiode as the detector, and the image was raster scanned over that single diode by two rotating ruby prisms. One was octagonal, and about a centimeter thick and five centimeters in diameter. The other was smaller, and rotated 90 degrees out from it. Together, this system formed the horizontal and vertical scan of the image. The photodiode was cooled by liquid nitrogen. The owner had brought a thermos of liquid nitrogen, and you just poured some into a compartment such that the photodiode was immersed and thus cooled.

The thing was remarkable. We played with it for a few hours before the owner came in and retrieved the device. He was thrilled that it was repaired and that it had so little damage. I think the thing cost around $35,000 back then. So he was understandably anxious about it.

Anyhow, you could easily see the heat in fluorescent light fixtures that had been shut off for many hours. And what was most amazing to me was that you could see warm footprints where someone had walked across a concrete floor 45 minutes ago!

It had adjustments that let you select a range of temperatures, and you could place a cursor in the image and it would tell you the actual temperature of that point in the view. Again, this was a remarkable device to me back then!

I wonder how these modern infrared cameras stack up against the performance of that old beast.

The guy who owned it did various surveys for people, mainly for industrial electrical systems and equipment. He said that a lot of what he found for people was imbalances in three phase power systems by just looking at the temperatures of transformer banks or wiring. He noted one case where he saw that a metal hand-rail in a power substation was warmer than the surrounding metal, and this showed that stray current was finding a path to ground via the handrail! He also did evaluations of insulation in buildings, etc.

It's neat to see that these new units will also show a warm footprint. But to see where someone had walked across a concrete floor 45 minutes ago, wearing shoes, still seems incredible to me. The difference in temperature has to be tiny.
Very cool stuff!
 
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IReallyLikePizza2

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I have the FLIR One that plugs into a phone, you can clearly tell in my roof where my solar panel ends. The very top of this image is the ridge, and the 2-3ft of roof before the solar panels start. Roof is much cooler where its covered by panels

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I also found this using the camera!

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Improper Alu to Cu connection, 20a breaker, wire rated for 15a and half the damn house going this connection, with no junction box!
 

J Sigmo

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I want one! I've just never sprung for any of them yet!

Aluminum wiring. Nasty stuff if not handled correctly.

People don't realize how quickly aluminum oxidizes, and how great of an insulator aluminum oxide is. It's sapphire! Hard, great insulator, and forms within minutes of exposing the bare aluminum.

Fine aluminum powder is an amazing "fuel" for an explosive.
 

J Sigmo

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I think the genius that wired that part of your place might be the guy who owned my house before we bought it. He was very frugal!

Connections behind walls with no junction boxes, and he liked to pull every centimeter of slack out of each box, too. You couldn't even pull a switch or receptacle out far enough to access the terminal screws. You had to cut the wires off just to get the devices out of the boxes! I've rewired a LOT of the place. He didn't use any aluminum, but still... ;)
 

TonyR

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I think the genius that wired that part of your place might be the guy who owned my house before we bought it. He was very frugal!

Connections behind walls with no junction boxes, and he liked to pull every centimeter of slack out of each box, too. You couldn't even pull a switch or receptacle out far enough to access the terminal screws. You had to cut the wires off just to get the devices out of the boxes! I've rewired a LOT of the place. He didn't use any aluminum, but still... ;)
Maybe the same dudes that wired my stepmom's place circa 1980. Around here, if Bubba can make a light bulb light up, he's an electrician. Circa Dec. 2019 my stepmom up the road called me, said her small heater in the bedroom went out and she could smell something.

Below is a picture of what happens when you daisy-chain outlet to outlet and use the push-in wire holes in the back instead of forming a loop in your wiring and using the side screws (these were 40 years old, before side clamps). Those back push-in holes have like a knife-blade to grab the conductor in a small area when compared to a good loop on the side screws. The voltage drop from that poor connection when using a 1500 watt radiant heater caused enough heat to burn the insulation as the heat conducted down the wire. This has been heating up for some time, as the copper has turned orange in color, an indicator it has lost its annealing and ductility, making it brittle. Further evidence is the ivory thermoplastic has turned brown.

I had to move so far down the hot and neutral conductors to cut out the brittle part I had to make a short pigtail, wire-nut and tape and come up to a new receptacle, which I then connected with the clamp and side screws. I also went downstream to the other 2 receptacles, replaced them with new and wired to utilize the side clamps and screws.

claudia-burnt_NEMA5-15R_121319_med.jpg
 
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J Sigmo

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The push in connections should be illegal!

I really like the receptacles with the side clamps. I always sort of hated the loop around the screw, even though it does make a good connection if used correctly! I'll pay more for better devices to get the clamp type connections! They're what I've become used to on contactors, relays, timers, power supplies, etc. But then we also get into the whole issue of using solid wire for the most part. I generally hate the stuff, but whatchagonnado?

I should show you a receptacle that was wired up no more than 9 years ago at the plant where I work as part of new construction when we added on to the building. Very similar effect, but in this case, the dummy managed to clamp the insulation of the wire under the side screw, leaving just a bit of copper touching the terminal. Fortunately, he left ample slack, so that even though I had to cut the wire back a few inches to get past the charred insulation, I was able to make the connection to the new receptacle with room to spare. That was a couple of years ago.

Just last week, a bank of lights in our large filter room stopped working. I got on a ladder and found exactly what I expected to find based on what we've fought for the years since this job was completed: A wire nut not installed correctly. In this case, it was tight (which was a big surprise), but the wire in question wasn't aligned with the others (too far back to be included in the "grip" of the wire nut), so all I had to do was take the connection apart, use a new GOOD wire nut, align the stripped ends, and install the nut properly.

This is probably the 20th or more bad wire nut connection that's hosed us since this work was done. Some of which have been found deep inside of conduits, nowhere near any junction box!!!!

The most horrifying thing I found (thankfully before we applied power) was where they'd connected one of the 120VAC hots to a contact in a small 480 3 phase motor starter panel to a terminal on the starter that would have tied it to one of the 480 phases!

In a way, I understand how this mistake was made because the boneheads who designed this starter arranged the terminals in a most confusing way that would naturally lead to this error. But still, I expect actual licensed electricians working on an industrial job to be more careful. I was just in there wiring up some control system wiring and happened to decide to check everything just to be sure my understanding of it all was 100% accurate.

Had we powered that part of the building up, the 480 would have been applied to a circuit that is the 120V control side of every motor starter, valve control, etc., for 2/3rds of the whole water treatment plant. People would have been without drinking water, perhaps for months, as we'd have had to buy replacements for a lot of toasted gear!

This is what comes out of regulations that require a municipality to put everything out for bid, and accept the low bidder for every job over a certain cost. The town dodged a bullet here, for sure. And the list of such things is long!
 
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