Best True RMS Multimeter for Electricians: Fluke 117 vs Klein MM720
Choosing the right multimeter can make electrical testing faster, safer, and more reliable. For electricians, a meter should handle everyday voltage checks, continuity tests, resistance measurements, current readings, and troubleshooting without becoming difficult to use.
A True RMS meter is especially useful when working with modern electrical systems that produce non-linear or distorted waveforms. This includes variable frequency drives, LED lighting, electronic power supplies, HVAC controls, and other equipment with switching electronics.
If you are looking for the best true rms multimeter for professional electrical work, two strong options are the Fluke 117 and Klein Tools MM720. Both are built for demanding jobs, but they serve slightly different users.
The comparison below gives you a quick look at their key features before we examine each meter in detail.
Table of Contents
Table of Contents
Quick Comparison: Fluke 117 vs Klein MM720
| Feature | Fluke 117 | Klein MM720 |
|---|---|---|
| Meter type | True RMS digital multimeter | True RMS digital multimeter |
| Best for | Professional electricians | Electricians and advanced DIY users |
| AC/DC voltage | Up to 600V | Up to 1000V |
| AC/DC current | Up to 10A | Up to 10A |
| Resistance | Yes | Yes |
| Capacitance | Yes | Yes |
| Frequency | Yes | Yes |
| Temperature | No | Yes |
| Low impedance mode | Yes | No |
| Auto-ranging | Yes | Yes |
| Safety rating | CAT III 600V | CAT IV 600V / CAT III 1000V |
| Display | 6,000 counts | 6,000 counts |
| Notable feature | Auto-V/LoZ | Wide measurement range |
| Ideal user | Electrical professionals | Electricians, technicians, maintenance users |
This table highlights the main differences, but your final choice depends on the type of electrical work you perform. The sections below explain where each meter has an advantage and which one makes more sense for different jobs.
1. Fluke 117: Best for Professional Electricians
The Fluke 117 is one of the most popular digital multimeters for electricians because it focuses on the measurements professionals use most often. It offers True RMS AC voltage and current measurement, automatic ranging, a large display, and a compact design.
Its biggest advantage is the Auto-V/LoZ function. Low impedance voltage measurement helps reduce false readings caused by ghost voltage, which can occur when conductors run close to energized circuits.
For electricians working on commercial buildings, residential panels, motors, lighting circuits, and HVAC equipment, this feature can save time during troubleshooting.
The meter also has a 6,000-count display and a built-in LED display light, which is useful when working inside electrical panels or in poorly lit areas.
Why electricians like the Fluke 117
- True RMS AC measurements
- Auto-ranging operation
- Low impedance mode for ghost voltage
- 600V measurement capability
- 10A current measurement
- Resistance, continuity, frequency, and capacitance functions
- CAT III 600V safety rating
- Compact and rugged construction
- Easy one-handed operation
The Fluke 117 is not designed to be the meter with the longest feature list. Instead, it focuses on practical electrical testing and makes common measurements quick.
Check the Fluke 117 Price on Amazon
If you want a proven professional meter with excellent everyday electrical troubleshooting features, the Fluke 117 is worth considering.
The Fluke 117 is particularly attractive for electricians who value reliability and simple operation over having every advanced measurement function built into one instrument.
2. Klein MM720: Best Feature-Rich Alternative
The Klein Tools MM720 takes a different approach. It provides a broad selection of measurement functions while offering higher maximum voltage specifications than the Fluke 117.
The MM720 can measure AC and DC voltage up to 1000V and includes functions for current, resistance, capacitance, frequency, temperature, and continuity.
Its temperature measurement capability can be useful for technicians who work around HVAC equipment, motors, electrical panels, and industrial systems.
The meter also carries a CAT IV 600V and CAT III 1000V safety rating, making it a strong choice for users who want broader electrical measurement capability.
Klein MM720 Key Features
- True RMS AC measurement
- Up to 1000V AC/DC voltage
- Up to 10A current measurement
- Resistance measurement
- Capacitance testing
- Frequency measurement
- Temperature measurement
- Continuity testing
- Auto-ranging
- 6,000-count display
- CAT IV 600V and CAT III 1000V rating
- Durable construction
For users who need a multimeter for electrical maintenance, industrial troubleshooting, HVAC work, and general electronics, the MM720 provides more functions than the Fluke 117.
Check the Klein MM720 Price on Amazon
If temperature measurement and a wider range of functions matter to you, the Klein MM720 can be an excellent value-oriented option.
3. Why True RMS Matters for Electricians
A standard average-responding meter can give accurate readings on clean sine-wave power. The problem appears when the waveform becomes distorted.
Modern electrical equipment often creates non-sinusoidal waveforms. Variable frequency drives, switching power supplies, LED drivers, UPS systems, and electronic controls are common examples.
A True RMS meter measures the heating effect of the waveform more accurately, allowing electricians to obtain more dependable AC measurements on many non-linear loads.
This does not mean every electrical measurement requires True RMS. For basic residential voltage checks on clean utility power, an average-responding meter may be sufficient. However, True RMS provides a useful advantage when troubleshooting modern electrical equipment.
For a wider comparison of professional meters, see our guide to best digital multimeter for electricians before making your final purchase.
4. Fluke 117 vs Klein MM720: Which Should You Buy?
Both meters can be good choices, but their strengths are different.
Choose the Fluke 117 if your work mainly involves:
- Residential and commercial electrical systems
- Circuit troubleshooting
- Electrical panels
- Lighting circuits
- Motors and controls
- Detecting ghost voltage
- Fast everyday measurements
Choose the Klein MM720 if you need:
- Higher voltage measurement capability
- Temperature measurement
- More measurement functions
- Industrial maintenance capability
- HVAC troubleshooting
- A versatile general-purpose multimeter
The Fluke 117 has the advantage of its dedicated low impedance function, while the Klein MM720 offers a broader feature set.
For many professional electricians, the Fluke 117 is the more focused choice. For technicians who want more functions from one meter, the MM720 can offer greater versatility.
5. What to Look for in a Professional Multimeter
The best true rms multimeter should not be selected by price alone. Electrical safety, measurement accuracy, usability, and the type of work you perform all matter.
True RMS Measurement
True RMS is valuable when measuring distorted AC waveforms from electronic equipment and modern power systems.
Safety Category Rating
Look for the correct CAT rating for your application. CAT III is commonly associated with building distribution and fixed installations, while CAT IV is intended for measurements closer to the utility service and source.
Never assume that a higher voltage number automatically makes a meter safe for every application.
Auto-Ranging
Auto-ranging reduces the need to manually select measurement ranges. This can speed up routine troubleshooting.
Low Impedance Mode
A low impedance function is useful for identifying whether a voltage reading is real or caused by induced or ghost voltage.
Build Quality
A professional meter may be used daily, carried between job sites, and exposed to dust, drops, and rough handling. Durable construction is therefore important.
Display Quality
A clear backlit display makes measurements easier to read inside panels, equipment cabinets, and other poorly lit areas.
6. Safety Tips When Using a Multimeter
Even the best true rms multimeter cannot compensate for unsafe testing practices.
Before taking a measurement, inspect the meter, test leads, and probes for damage. Confirm that the leads are connected to the correct terminals and that the selected measurement function matches the circuit.
Never measure resistance or continuity on an energized circuit. When measuring current, make sure the meter is connected correctly in series and that the circuit current is within the meter’s rated limit.
Use properly rated test leads and personal protective equipment when required. Always follow the electrical safety procedures applicable to your workplace.
7. Which Is the Best Choice for Most Electricians?
For a professional electrician who wants a dependable meter for everyday troubleshooting, the Fluke 117 is a particularly strong choice. Its Auto-V/LoZ function, straightforward controls, True RMS measurement, and rugged professional design make it well suited to electrical service work.
The Klein MM720 is the better option when you want a wider selection of measurement functions and higher voltage capability. Its temperature function can also be useful for HVAC and maintenance applications.
Before buying, think about the equipment you test most often. A residential electrician may value simplicity and ghost-voltage detection, while an industrial technician may prefer additional measurement functions.
If you are comparing options beyond these two models, our guide to best digital multimeter for electricians can help you compare additional meters based on safety ratings, measurement functions, durability, and job type.
Final Verdict
The Fluke 117 and Klein MM720 are both capable True RMS digital multimeters, but they are designed with slightly different priorities.
The Fluke 117 is the better fit for electricians who want a focused professional meter with excellent everyday troubleshooting features and low impedance voltage measurement.
The Klein MM720 is a strong alternative for users who want more measurement functions, temperature testing, and higher voltage capability.
For professional electrical work, the best true rms multimeter is ultimately the one that matches your actual testing needs, safety requirements, and working environment. For most electricians focused on everyday electrical troubleshooting, the Fluke 117 is the standout choice.
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Frequently Asked Questions
1. Is True RMS better for electricians?
Yes. True RMS can provide more accurate AC readings when dealing with distorted waveforms. This is useful when testing variable frequency drives, electronic equipment, LED drivers, UPS systems, and other non-linear loads.
2. Is the Fluke 117 good for professional electricians?
Yes. The Fluke 117 is designed with electricians in mind. Its True RMS measurement, Auto-V/LoZ function, automatic ranging, and rugged construction make it suitable for many residential and commercial electrical applications.
3. Is Klein MM720 better than Fluke 117?
Neither is universally better. The Fluke 117 has an advantage for everyday electrical troubleshooting and ghost-voltage detection, while the Klein MM720 offers more measurement functions and higher voltage capability.
4. What does LoZ mean on the Fluke 117?
LoZ means low impedance. The Fluke 117 uses low impedance measurement to help reduce false voltage readings caused by ghost or induced voltage on disconnected conductors.
5. What safety rating should an electrician look for?
The required rating depends on the electrical environment. CAT III is commonly used for fixed building installations, while CAT IV is intended for measurements closer to the service entrance and utility source. Always select a meter and accessories rated for the specific application.
If you need more help choosing the right professional meter, compare the features in our best digital multimeter for electricians guide before buying.
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