FLIR A38 Thermal Imaging, Fluke Multimeters, and 12-Inch Calipers: A Field Tech's FAQ

I'm a senior field service technician at an industrial maintenance company. I've handled 700+ emergency callouts in 11 years, including a same-day motor failure at a food plant where the restart window was six hours. In that world, the right tool isn't the one with the most features. It's the one that answers the question before the deadline.

When I first started doing diagnostics, I assumed the most expensive multimeter was the most important tool in my truck. Three years later, I realized I was wrong. A thermal imager can show you a problem a meter can't reach until it has already caused a shutdown. That lesson changed how I work.

Here are the questions I actually get asked about my kit:

• What is the FLIR A38 thermal imaging camera good for?
• Can thermal cameras see through glass?
• What is the best Fluke multimeter for electricians?
• Is the Fluke 189 multimeter still worth it?
• Do I need a 12-inch caliper?
• When should I grab a thermal camera instead of a multimeter?
• Should I buy a cheap thermal camera or save up?

What Is the FLIR A38 Thermal Imaging Camera Used For?

The FLIR A38 thermal imaging camera is a fixed-mount industrial thermal camera. It is not a handheld scanner. It sits in one position, watches a target, and records temperature data continuously. I use cameras like this for electrical panels, conveyor bearings, motors, and steam systems.

Last September, a plant had an intermittent trip on a compressor feeder. By the time I arrived, the breaker was cold and the meter showed nothing. The A38's logged data showed the same terminal had hit 72°C at 4:12 AM, again at 4:47 AM, and again at 5:03 AM. That historical record told me exactly which terminal to inspect. We found a loose lug. The whole repair took 40 minutes.

That is the real value of a fixed thermal imager. It sees the fault while it's happening, even when you're not physically there. The cost is higher than a handheld camera. But in an emergency, the saved downtime pays for it.

Can Thermal Cameras See Through Glass? (FLIR Included)

No. And I do not mean 'most thermal cameras.' I mean none of them work through ordinary glass, including FLIR. Glass reflects infrared radiation and blocks most of what it does not reflect. The thermal image you get from a window is the glass surface temperature plus reflections from the camera and nearby heat sources. It is not a picture of what's behind the glass.

I've had a facility manager argue that his FLIR One showed him a hot wire behind a window. It didn't. It showed the reflection of a heat source somewhere in the room. The moment we opened the door and imaged from the correct side, the hot spot was in a different location entirely.

Honestly, I fell into the same trap in 2023. I knew glass would reflect, but I thought 'what are the odds?' and let a client talk me into imaging a closed window. It was the one time that shortcut could have caused a misdiagnosis. I never made that mistake again.

If you need to inspect something behind glass, open the enclosure or move to a line of sight. It is physics. No expensive upgrade changes it.

What Is the Best Fluke Multimeter for Electricians?

The best Fluke multimeter for electricians is the Fluke 117 for most service work, and the Fluke 87V for industrial electronics. The 117 is compact, has a CAT III 600V rating, and includes non-contact voltage detection. That makes it a great everyday meter for troubleshooting outlets, panels, and lighting circuits. The 87V is built for harsher industrial conditions. It has higher accuracy, more measurement features, and handles variable-frequency drives better.

If someone asks me what is the best Fluke multimeter for electricians, my answer is always: it depends on what you do every day. Do not buy the 87V just because it's the most expensive. Buy the 117 if it covers ninety percent of your calls. Buy the 87V if you regularly work around motor drives and need more measurement confidence.

I would not buy a no-name meter to save $150. A meter that gives you uncertain voltage readings is not a bargain. It is a liability.

Is the Fluke 189 Multimeter Still Worth Buying?

The Fluke 189 multimeter is an older high-accuracy logging meter. If you find a used 189 that has been recently calibrated, it can still do solid electrical work. It has true RMS, high accuracy, and data logging. In its time, it was one of the best handheld meters you could own.

But if you are shopping for a new meter, I would not choose an old 189 over a current Fluke model. The warranty is gone, parts get harder to find, and the battery life is not close to modern meters. The hidden cost is the downtime if it fails in the middle of a job. A $350 used meter that dies in week two is not a good deal.

My honest position: the 189 is a great tool if you already own a calibrated one. It is not a smart first purchase in 2025.

Do I Need a 12-Inch Caliper in the Field?

When someone asks me about a caliper 12 inch model, my first answer is: maybe. It is a shop tool, not a carry-everywhere tool. I use mine for motor shaft diameters, pulley bores, bearing fits, and custom shims. A 6-inch caliper can't reach across those parts.

If you do regular mechanical work, a 12-inch caliper earns its space in the truck. If you only do electrical troubleshooting, you probably don't need one. The same logic applies here as with meters: buy for the jobs you actually do, not the jobs you imagine doing.

Thermal Camera or Multimeter: Which Should I Grab?

This is the most practical question. A multimeter tells you if voltage is present. A thermal camera tells you if something is heating up when it shouldn't. They are not either/or. They complement each other.

I had thirty minutes before a plant restart. Normally I would have checked load current on every phase and then imaged the panel. There was no time for both. I chose the thermal camera because it showed a hot connection at the same time as a slightly lower current reading. I replaced the connection and the meter confirmed the repair. It worked. But I made that decision under pressure, with incomplete information. It could have gone the other way.

Do not make a habit of skipping the meter because the camera is faster. The camera points you to the problem. The meter proves what the problem is. Use both.

Should I Buy a Cheap Thermal Camera or Save Up?

I'm not going to say every cheap camera is trash. But thermal imaging is one place where the lowest price creates the highest hidden cost. A low-resolution sensor can miss a small hot spot. Unstable emissivity settings give you readings that you can't trust. Bad software makes it hard to document what you found.

Is the premium worth it? For a professional, yes. The FLIR A38 thermal imaging camera is not the cheapest fixed camera, but it gives you a clear, repeatable, documented view of the equipment. That is valuable when you have to explain your findings to a customer or supervisor. The worst cost in this job is not the equipment. It's the failed repair caused by bad data.

Buy the best thermal camera you can justify. Just do not buy the cheapest one and hope it works.