Fluke vs Klein Multimeter: A Maintenance Technician on True RMS, Sensor Troubleshooting, and ifm Pressure Sensors

Why I Stopped Guessing and Started Comparing Fluke vs Klein Multimeters

I've been servicing industrial controls for 8 years. I've personally made, and documented, 11 significant measurement mistakes, totaling roughly $6,000 in wasted budget. One of those mistakes ended with two perfectly good ifm pressure sensors sitting in a parts bin. This article is not a spec-sheet war. It's a field-level comparison of Fluke and Klein true RMS multimeters, using the Fluke 117 and the Klein MM700 as the main examples. If you're in the middle of a Fluke vs Klein multimeter debate, these are the dimensions that actually matter.

Verify the signal, not the sensor. If you can't trust your multimeter, you'll throw good parts at bad wiring.

The $480 Sensor Mistake That Made Me Care

In September 2019, a hydraulic press kept tripping on erratic pressure. I diagnosed a failed ifm pressure sensor and replaced it. The fault returned. I was about to order another one when a co-worker removed the panel cover and measured 24 V at the PLC but only 22.8 V at the sensor connector. The 1.2 V drop came from a corroded terminal block. The sensor was fine all along. That mistake cost $480 in parts and about six hours of downtime.

The lesson is not 'buy a better brand.' The lesson is that a poor measurement decision is expensive no matter who made the sensor. ifm pressure sensors are reliable. The problem was my verification procedure, not the sensing element. That is exactly why the multimeter matters.

Why a Multimeter Is the Bridge Between a Sensor and a Verdict

A sensor only reports what it sees. A bad ground, a loose terminal, a misconfigured analog input, or a distorted supply voltage can all look like a failed sensor. A good true RMS multimeter shows you where the problem is. A bad one gives you confident nonsense.

Last winter, a tank temperature reading started drifting. I almost ordered a replacement ifm temperature sensor. Instead, I checked the 4-20 mA loop with a process meter. The current matched my hand-held thermometer. The sensor wasn't bad; the PLC analog input had been reconfigured by accident. That kind of check is routine, but only if you trust the tool in your hand.

Dimension 1: True RMS and Low Impedance

Both the Fluke 117 and the Klein MM700 are true RMS meters. That should be your first filter for any industrial work. Variable frequency drives, servo drives, and battery chargers create non-sine waveforms. An average-responding meter can read those waveforms with complete confidence and still be wrong.

In my first year, I made the classic money-saving mistake: I bought a cheap average-responding meter because I was only checking voltage. The first time I used it on a VFD circuit, the numbers made no sense. A senior tech's true RMS meter made sense immediately. I replaced that meter and never went back.

True RMS is the baseline, but it is not the whole story. The Fluke 117 has a LoZ mode that drains ghost voltages. The Klein MM700 also has a LoZ mode. If you've ever read 48 V on a cable that was supposed to be dead, you know why that matters. Ghost voltages send you chasing faults that do not exist.

Dimension 2: Safety Ratings and the Non-Contact Tester

Buying a multimeter is not like buying a phone. The internal protection can be the difference between a blown fuse and a serious arc flash. According to the manufacturers' published specifications, the Fluke 117 is rated CAT III 600 V, and the Klein MM700 is rated CAT IV 600 V / CAT III 1000 V. That makes the Klein a bit more flexible around service entrances. It does not mean one is automatically safer. The meter, leads, and technique all have to be matched to the environment.

I keep a Fluke 1AC II Non-Contact Voltage Tester in my shirt pocket and use it before opening any panel. It is a presence check, not a measurement. The 1AC II can tell you a circuit is 'probably dead' or 'likely live', and then I confirm with a two-probe meter. The 1AC II has warned me twice about a panel labeled 'disconnected'. The non-contact tester is a companion to a good multimeter, not a replacement for one.

Dimension 3: Daily Usability

Where these two meters differ the most is not accuracy. On a clean 480 V supply, both read correctly. On a clean resistance check, both read correctly. The differences show up in daily habits.

The Fluke 117 is compact and easy to carry in a small pouch. The Klein MM700 has a bigger rubberized body and a stand that I genuinely like. A colleague who does residential service prefers the Klein because it offers more ranges for the price. I prefer the Fluke's LoZ access. Neither preference is objective. The best meter is the one you will actually carry.

One honest surprise: I expected the less expensive Klein to feel like a downgrade. It did not. It has a different feature set, including a higher CAT rating and more measurement functions. That does not make it 'better' than the Fluke. It makes it a different tradeoff.

Dimension 4: Price vs Cost of a Wrong Diagnosis

Price is where the comparison gets emotional. From online distributor listings I checked in early 2025, the Fluke 117 was roughly $170-$220, and the Klein MM700 was often $100-$150. Those numbers change, so verify current pricing. The difference is usually less than one service call.

If a cheaper meter leads to one false sensor replacement, the savings disappear. But I don't think the answer is always 'spend more'. It's 'spend on the features that prevent the mistake'. True RMS, LoZ, and a proper CAT rating are not luxury options. They are the difference between finding a voltage drop and replacing a sensor that was never broken.

Which One Should You Buy?

If you troubleshoot VFD-driven systems, check sensors in control panels, and want a compact true RMS meter with LoZ, the Fluke 117 is worth the premium. If you want a broader feature set, including current, temperature, and a higher CAT rating, and you don't mind a bulkier tool, the Klein MM700 is a legitimate choice. If you only need a quick presence check, the Fluke 1AC II Non-Contact Voltage Tester is enough—but it is not a substitute for a meter.

And if you are diagnosing an ifm pressure sensor or an ifm temperature sensor, start with the sensor's actual output before ordering a replacement. Many ifm sensors with IO-Link can show you the digital process value, but when the sensor is wired as 4-20 mA, the loop still needs to be verified with a tool you trust.

Before You Replace the Sensor: A Short Checklist

• Measure supply voltage at the sensor, under load.
• Check the sensor output with the correct range and a meter you trust.
• Wiggle the connector while watching for intermittent changes.
• Use a true RMS multimeter for any AC signal driven by a VFD.
• After a non-contact tester says safe, confirm with a two-probe meter.

The Meter Is the Bridge

After the third false 'sensor failed' report in Q1 2024, I created our pre-replacement checklist. We've caught 34 potential misdiagnoses since then. That did not happen because I switched brands. It happened because I started comparing meters on the things that matter: safety, true RMS, LoZ, and whether the meter is comfortable enough to actually use.

Fluke and Klein both make tools that can do the job. The hard part is choosing the one that matches how you work—and then using it before you replace a sensor. When you show up with a proper meter and a checklist, the customer sees a technician who does not guess. That impression is worth more than the price difference.