I'm an office administrator for a mid-sized industrial services firm—about 150 people across two locations. I handle all our test equipment and inspection tool orders, roughly $60k annually across maybe 8 or 9 vendors. It's my job to make sure the maintenance crews have what they need before they realize they need it. (Should mention: I learned this the hard way after a $1,200 rush order on a thermal camera in January last year. The finance team was thrilled.)
So when I get asked about thermal cameras—and I get asked a lot—it's usually from our senior field techs or the facilities manager. They want something specific. They want a sensor, not just a toy. And they want to know if upgrading to a thermo-only device is worth it when they already have a solid multimeter like the Fluke 117.
Let me break down a comparison I've made for our team a few times: the FLIR A35 thermal camera (that fixed-mount sensor module) versus the FLIR One Gen 3 (the smartphone attachment). And I'll explain why that Fluke 117 is still the tool they'll grab first.
Why Compare These?
It's tempting to think thermal cameras are all the same—point, shoot, see the hot spot. But in a B2B maintenance workflow, the difference between a fixed-mount sensor and a handheld device is huge. The A35 is a camera sensor, basically a black box you wire in. The One Gen 3 is a portable visualizer you pair with your phone.
They serve different roles. But I keep seeing people try to use one where they should use the other. Let me show you what I mean.
Dimension 1: Sensor Capability vs. Portability
The A35: A Real Sensor for Fixed Monitoring
The FLIR A35 thermal camera is a rugged, fixed-mount sensor with a 320 x 256 pixel thermal array. It's designed to be embedded in a monitoring system—think conveyor belt hot spots, server room racks, or mechanical rooms you want to watch 24/7. It's not a handheld tool. You hook it up to a controller (or a PC) and feed the data into your SCADA or logging software.
I've had our facilities manager ask for one after a near-miss on a motor bearing. The idea is you mount it, aim it, and let it run. (In our case, we set it up in the main electrical room to monitor breaker panel temps during a summer heatwave. It paid off when we caught a 40°C rise in one cabinet before it caused a trip.)
It's not something you carry around. But if you need continuous, automated monitoring, it's the right approach.
The One Gen 3: Portable, but Limited
The FLIR One Gen 3 is the opposite. It's a small attachment for your phone (Lightning or USB-C). It has a 160 x 120 pixel thermal sensor—lower resolution, but enough for quick troubleshooting. You can snap a thermal image, measure spot temperatures (from -20°C to 400°C), and even save a visual photo overlay (MSX technology, which blends thermal and visible light).
Our lead electrician uses one for initial walkthroughs. He can quickly scan a panel, find the hot breaker, then decide if it needs a deeper look. It's fast. But the resolution difference matters. The A35 will spot a hot spot on a pipe at 15 feet. The One Gen 3 might miss it until you're 3 feet away.
Conclusion: If you need continuous monitoring, the A35 is the sensor. If you need a portable visualizer for spot checks, the One Gen 3 works—but don't expect lab-grade accuracy.
Dimension 2: Integration vs. Standalone Use
The A35: Built for Integration
The A35 is designed to feed data to a system. It has GigE Vision and GenICam support (those are standards for industrial cameras). And it can output 60 frames per second. That means you can log temperature data, set alarms, and trigger actions automatically. For example: if a conveyor motor hits 80°C, the system can shut down the line before the bearing seizes.
For us, setting up the A35 meant running cables and installing software. Not hard, but not a quick job. (Note to self: next time, order the bracket kit and the 10-meter cable upfront. The standard 5m cable is too short for most installations.)
The One Gen 3: Simple, but Isolated
The One Gen 3 is mobile-first. You use the FLIR ONE app on your phone. You can capture images, add notes, and export a report or CSV. But it's not connected to a monitoring system. You won't get an alert when a temperature threshold is crossed (unless you happen to be looking at the screen). And you can't integrate it into your existing infrastructure.
That makes it perfect for drive-by inspections but useless for 24/7 monitoring.
Conclusion: If you need the camera to talk to your system, the A35 is the only choice. If you just need a quick look now and then, the One Gen 3 is much simpler.
Dimension 3: The TG165-X and Why Your Fluke 117 Still Matters
I've also had to order the FLIR TG165-X MSX thermal camera for some of our crews. It's a handheld, gun-style thermal imager with a built-in spot thermometer. It's a middle ground: more rugged and dedicated than the One Gen 3, but not as capable as the A35. It's useful for electricians doing service calls who want to see hot spots without pulling out a phone.
But I want to clarify something. A thermal camera—whether it's an A35, a One Gen 3, or a TG165-X—doesn't replace a good multimeter. It's a complement.
A lot of people assume that seeing a hot spot on a thermal image means you can skip the electrical measurements. That's a dangerous oversimplification. The assumption is that if the panel looks cool, it's safe. But in reality, a resistive connection can be hot only under load, and by the time you see it glowing on a thermal image, you've already got a problem.
I didn't fully believe this until I ignored it. Our senior electrician was doing a routine check on a 3-phase motor starter. The thermal image looked clean. But he used his Fluke 117 true RMS multimeter to check voltage drop across the contacts. Turns out there was a 15% imbalance on one leg. That imbalance wasn't producing enough heat to see on a quick scan, but it was a sign of contact wear that could have caused the starter to fail under full load a week later. The Fluke 117 caught it. The thermal camera would have missed it.
Conclusion: Don't think thermal imaging eliminates the need for electrical diagnostics. They work together. The thermal camera tells you something is hot. The multimeter tells you why.
Which One Should You Buy?
Buy the FLIR A35 If:
- You need continuous, automated monitoring of equipment or panels.
- You have the infrastructure to integrate it (cables, software, mounting).
- You care about high-resolution data logging (60 fps, 320x256).
Buy the FLIR One Gen 3 If:
- You want a portable visualizer for quick spot checks.
- You're on a budget (it's significantly cheaper than the A35).
- You don't need integration or continuous monitoring.
Keep Using Your Fluke 117 If:
- You want to measure voltage, resistance, or current (thermal cameras can't do that).
- You want to confirm electrical connections under load.
- You want a rugged, reliable handheld tool that works without a phone.
Final thought: I've seen too many maintenance teams buy a thermal camera and assume their old multimeter is obsolete. That's not how it works. The thermal camera adds a new dimension to your diagnostics, but the multimeter is still the workhorse. Keep both. Use them together. And if you're ordering for a team (like I do), make sure you order the right tool for the right job. (Mental note: the A35 doesn't come with a cable longer than 5 meters. You'll need to order that separately. Don't ask how I learned that lesson.)
