What is a clamp meter? And what are the best clamp meters for electricians you should choose?
We have tested and compared the best clamp meters for electricians, and in this guide, we will share our findings and review our top 5 choices.
Before we go to the reviews, however, let us begin by discussing the definition of the clamp meter itself.
What Is a Clamp Meter?
A clamp meter is, in a nutshell, an electrical test tool that is a hybrid between a digital multimeter and a clamp.
Clamps, or to be exact, current clamps, are used to measure current, while probes measure voltage. It is called a clamp because it has hinged jaws which open, and so we can clamp these jaws around a cable or any conductors. This clamping allows us to measure the current in that circuit without disconnecting the cable, and so it won’t disrupt the operation.
These clamp jaws are typically made of ferrite iron and are designed to detect and measure the magnetic field generated by the current.
However, modern clamp meters typically offer more measurement functions other than the main current measurement function. Some products also offer various technologies to improve accuracy and also to allow specific measurement features.
Today’s clamp meters (including the ones we’ll review below) include most of the typical functions of a digital multimeter like voltage measurement and resistance measurement.
You might also want to check out our previous guide of digital multimeters (DMM) here to get a clearer picture.
Types of Clamp Meters and How They Work
There are two main types of clamp meters available in the market today, which are based on the types of the measured current. They are:
- Current-Transformer Clamp Meter: can only measure AC current
- Hall Effect Clamp Meter: can measure both AC and DC currents
Current-Transformer Clamp Meter
A current-transformer clamp meter uses two ferrite iron clamps that are independently wrapped with copper coils. The main principle is that the combination of ferrite iron and copper coils forms a magnetic core, which allows the measurement to happen.
When the arm of the clamp meter is placed on a conductor, the magnetic wave generated from the clamp meter acts as the secondary winding, of which the iron core of the clamp concentrates the magnetic field of the conductor (or cable).
Due to this action, a new current in proportion to the primary current is generated by electromagnetic induction. This new current is what actually measured by the measurement device inside the clamp meter, which will produce the current reading.
Hall Effect Clamp Meters
Hall effect clamp meters also utilize two ferrite iron clamps. The main difference is that these clamps are not wrapped with copper coils. Instead, in hall effect clamp meters, the current flowing through the conductor is concentrated in the one or more gaps of the ferrite iron core, whenever the clamp jaws close around the cable or the conductor.
If we look closely at the clamp tips of hall effect clamp meters, we can see at least one gap between the two jaws in the clamp’s core. This gap creates an air pocket that is passed by the magnetic field of the conductor. This will also limit the magnetic flux and so ensure the core won’t be saturated by the magnetic field.
Inside the gap is a semiconductor unit we call a hall effect sensor, which is covered with a plastic molding (so we can’t see it). The hall effect sensor is essentially a variable-voltage transducer that can adjust its output voltage based on the conductor’s current. The voltage generated by the sensor is then amplified and scaled to represent the measured current.
Since the clamp’s core and the gap are able to concentrate on DC magnetic fields, hall sensor clamp meters can also measure DC current.
How To Measure Current Using a Clamp Meter
Although different clamp meters might have their own unique features and measurement methods, here are the general steps in using a clamp meter to measure current:
- If the probes are attached to the clamp meter, remove them first
- Switch the clamp meter ON
- If you can choose between AC or DC current, make your choice using the dial switch. After that, the display should indicate that it’s now ready to measure current. Typically the display should show a jaw sign or similar icons.
- Place the conductor in the center of the clamp, then close the clamp’s jaws. Level the conductor between the alignment marks that should be on the jaws.
- The display should now show the desired reading. Depending on your model, you can change the display’s resolution based on your needs.
Important Features To Consider in a Clamp Meter
RMS stands for root mean square, and if your clamp meter comes with a true RMS feature, it simply means the meter can convert AC signals into DC signals of equivalent value. So, a true RMS meter can accurately measure pure waves, as well as non-sinusoidal waves.
AC current is represented as a sine wave because it reverses directions several times per second (alternating). On the other hand, the amplitude of a sine wave will change continuously over the wave period, and so current measurements will vary depending on when you measure this sine wave, and so it might not be accurate.
True RMS simply tackles this accuracy issue.
IP, or Ingress Protection rating will tell us the degree of enclosure protection employed by the clamp meter unit, especially against water, moisture, and other external factors. A well-protected instrument means we can use it in more places and conditions. Some models use NEMA instead of IP rating.
Auto-ranging clamp meters can automatically set the correct measurement range. So, users wouldn’t need to adjust the switch and dial positions while trying to properly clamp the conductor. Auto-ranging feature, simply put, will save time and improve the unit’s ease of use.
Different clamp meter units come with different display units. The display can come in different sizes, resolutions, and some might have back-light and some don’t. The better the display, the easier we can view and analyze the readings.
The unit’s internal memory. The more memory it has, the more measured values can be recalled later.
The inrush feature provides users with an accurate measurement of current surges/spikes that typically flow into electric appliances and motors during startup. Inrush can be a very important feature to have when troubleshooting various appliances.
Why You Need a Clamp Meter: Pros and Cons
First, let us discuss the benefits of using a clamp meter:
- Clamp meters filter out noise, and can provide accurate and stable readings for various applications.
- Versatile, can be used in noisy electrical situations and environments
- Typically slim and ergonomics, so we can easily hold it when wearing protective gloves
- Most models can measure low-level DC current
- Fast measurements, so can save time
- Newer clamp meters come with extra features for a wide range of measurements
However, there are also several limitations of clamp meters in electrical measurements:
- It is mainly a current-measuring tool, so not all models can measure voltage accurately
- Measures to the nearest tenth or hundredth of a unit. On the other hand, digital multimeters can measure in milliunits (millivolts, milliamps, and milliohms), so DMMs are generally more precise.
Top 5 Best Clamp Meters
Below, we will discuss five of the best clamp meters for electricians we have tested. Each of them has their own advantages and disadvantages, and maybe even more importantly, price points.
Without further ado, let’s rundown the list of the best clamp meters for electricians starting from our 5th place contender right through to our top picks!
#5. Klein Tools CL600 Digital Clamp Meter
- Size: 7 in. x 3.02 in. x 1.61 in.
- Weight: 12 oz
- Automatically ranging true RMS technology for improved accuracy
- Measures AC current, AC/DC voltage, resistance, continuity, DC micro-amps, frequency, capacitance, and can test diodes through the included test leads
- Thermocouple probe included, can measure temperatures
- Durable and sturdy, can withstand a 3.3’ (1 m) drop without breaking
- CAT-III to 600 V, Class 2, double-insulation safety rating
Pros and Cons
- Very affordable for its features
- Thermocouple probe included, so can measure temperatures accurately
- Features a low-battery indicator
- Very sturdy and durable built
- Low-impedance, so it’s energy-efficient
- Double insulation to provide an extra layer of protection
- Bulky and not very ergonomics to grip
- The included leads are relatively low quality
Another one from Klein, the Klein CL600 is more affordable than the CL800 that is discussed above. Similar to the CL800, the Klein CL600 offers auto-ranging true RMS technology which can provide more accuracy in your readouts.
For its very affordable price, the Klein CL600 also offers a thermocouple probe so we can take temperature measurements.
The Klein CL600 also offers a relatively large, high-quality display with a decent amount of backlight, and it’s fairly easy to read the measurements.
Overall this is a very decent clamp meter if you only take non-professional measurements around the house. For general-purpose professional measurements, however, the leads aren’t high-quality enough and might break after prolonged use.
#4. Fluke 323 True-RMS Clamp Meter
- Weight: 9.3 oz
- Size: 8.15 in. x 3 in. x 1.34 in.
- Slim and ergonomic design
- True RMS for AC accuracy
- Measures up to 600V AC/DC
- 400A AC
- CAT-IV safety rating to 300V
Pros and Cons
- True RMS measurement with exceptional technology
- Measured to 400A and 600V AC/DC
- Pretty decent accurate proportions
- Large display combined with slim and ergonomic design
- Display hold feature
- Audible continuity buzzer
- Doesn’t measure DC amps
- Display not backlit
- Carry case a bit small and tight
The Fluke 323 is not really a top-end Fluke clamp meter, but it is still a pretty accurate and reliable clamp meter as expected from the Fluke brand.
The Fluke 323 is a clamp meter that focuses on the basic functionalities without providing you with any fancy features (which in most cases we don’t use much anyway), and so the Fluke 323 can be a great choice for engineers and technicians that prefer simplicity. Also, due to its simplicity, it is very easy to use in most situations.
The main functionality of the Fluke 323 —as with any clamp meters—, is to measure current indirectly. The 323 can only measure AC (and not DC) current, so it might be an issue for certain maintenance situations. It can, however, measure up to 400A AC, which is a pretty decent number.
Like most of the decent clamp meter products available, the Fluke 323 is rated for CAT III installations to 600 V measurement and CAT IV installations to 300V. As you can see, it can measure up to 600 V with true RMS measurement, so you’ll get fairly accurate readings.
It can also detect non-contact voltage and includes an audible continuity signal, which can tell you when there’s a live wire. So, we can conclude that the Fluke 323 is a safe, easy to use, and pretty versatile clamp meter, suitable for most general-purpose measurements.
#3. Klein Tools CL800
- Weight: 12.3 oz
- Size: 9 in. x 3.8 in. x 1.5 in.
- Jaw size: 1.38 in.
- True RMS measurement with auto-ranging
- Can perform continuity and frequency
- Can measure voltage, resistance, capacitance, and frequency
- Low-impedance mode to pick up ghost voltages
- Temperature measurements via the included thermocouple
- CAT-IV rating at 600V
Pros and Cons
- Pretty accurate measurement for AC and DC amperage and voltage
- Versatile with various multimeter ranges, including capacitance
- Flashlight function
- Temperature input (thermocouple included)
- Durable and sturdy build
- Backlit illuminated display
- Easy to use with fixable probe leads
- Non-contact voltage checker feature
- Can take a while to get readings
- At certain range and angles, the screen is prone to washing out with backlight
Unlike the Fluke 323 discussed above, the Klein CL800 can measure both DC and AC voltage and also capacitance, resistance, and frequency. It can also test diodes through the test leads, making it a versatile clamp meter for both most testing needs.
You get many functions like in a standard multimeter, and it can measure high volts and amps fairly accurately. It can measure up to 600 A (again, for both AC and DC).
With all these different functionalities, the Klein CL800 is fairly easy to use, as you can choose between all these features through just one dial setting and a select button to switch between AC and DC amps.
It can measure 100V on CAT-III circuits and 600V on CAT-IV circuits, and it is true RMS. So, we can easily read AC and DV voltage and current at a high degree of accuracy.
The Klein CL800 also features a strong magnet that allows it to latch to metal surfaces, which can add to the convenience in various testing and troubleshooting situations. It also includes a fairly large LCD display that is also backlit, so you can easily see the readings.
The key value of the Klein CL800, however, is the fact that with all these features, it is a fairly affordable clamp meter, only slightly more expensive than the Fluke 323 discussed above. A very versatile and accurate clamp meter for its price.
#2. Fluke 324 True RMS Clamp Meter
- Weight: 7.3 oz
- Size: 8.1 in. x 3 in. x 1.3 in.
- True RMS measurement provides accurate readings, can measure both linear and non-linear loads, regardless of waveforms
- Measures AC current up to 400A, resistance to 4kiloohms, and AC/DC voltage to 600V
- Jaw opening can measure current in a conductor up to 30 mm without touching and/or interrupting the circuit
- CAT IV installations to 300V and CAT III installations to 600V
- Slim and ergonomic design
- Large back-lit display
Pros and Cons
- Compact and ergonomics
- Can measure AC and DC voltages up to 60V limit
- Audible continuity sensor
- Large backlit display
- Versatile set of features
- Can measure temperatures with included thermocouples
- Lacks analysis in low temperature
The Fluke 324, as the name suggests, is the more powerful brother of the Fluke 323, that we have reviewed above. It is (significantly) more expensive than the 323, at almost double the price. So, the question is whether the differences in features and functionalities can justify the price difference.
The main difference from the 323 to this model is that the 324 can measure both capacitance and temperature up to 1000 mF, making it a better clamp meter if you want to test HVAC equipment.
Also, the Fluke 324 has a back-lit display, unlike the 323, so you can use the 324 in the dark. With the Fluke 324, we can measure resistance up to 4 k-ohms, so it’s very versatile.
The Fluke 324 features the true RMS technology that is also available in the 323, which allows us to measure linear or non-linear loads with very high accuracy. As a result, it can provide accurate measurements of AC/DC for up to 400 amperes.
Since its jaw can open up to 30mm, it can measure the current in various electrical appliances without touching or disrupting the circuit.
The Fluke 324 has a thin and ergonomic design, perfectly fits in your hand to perform its wide range of features. It’s a little expensive (the most expensive in this list), but it does offer a more versatile set of features compared to the other products we have reviewed above.
#1. Fluke 375 FC 600A AC/DC TRMS Wireless Clamp
- Weight: 1.10 pounds
- Size: 9.685 in. x 3.267 in. x 1.692 in.
- Measure AC/DC current via the clamp
- Features a VFD low-pass filter which provides accurate motor drive measurements
- Connects wireless to any smartphone over bluetooth
- CAT-III to 1000V, CAT-IV to 600Vclass 2, double insulation safety rating
- 600 A ac and dc current measurment
- 2500 A ac current measurement with (optional) iFlex flexible current probe
Pros and Cons
- Durable and sturdy with a high drop rating.
- True-rms voltage and current for accurate measurements on non-linear signals
- Bluetooth connectivity keeps you away from the arc flash zone
- Transmit measurements wirelessly via the Fluke Connect app or Fluke Connect Assets software
- Create reports and share with your team without leaving the field
- Line splitter feature included
- Double insulated for extra safety
- Back-lit display
- The included case is small and won’t hold all accessories
Our #1 pick for the best clamp meters for electricians goes to the Fluke 375. The Fluke 375 is the most expensive clamp meter on the list, however, a small price to pay for one of the best clamp meters on the planet..
The Fluke 375 has an integrated low pass filter and state of the art signal processing which makes it ideally suited for noisy electrical environments while providing stable readings.
The Fluke 375 features a backlit LCD display so it’s easy to read the measurement even in dark conditions. It’s sturdy and robust, but keep in mind that it doesn’t feature a true RMS measurement.
The wireless bluetooth feature and logging capability of the Fluke 375 makes it the most powerful and safest meter on the list.
Overall, the The Fluke 375 is without question our #1 pick for the best clamp meters for electricians.
Best Clamp Meters for Electricians – Final Verdict
All five of the best clamp meters for electricians we have reviewed above are of great quality and each comes with their own advantages and disadvantages. So, choosing the absolute best among them is a very difficult task.
However, for the sake of this buying guide, our choice goes to:
We hope you’ve gathered enough information from this buying guide, and can make a better purchase decision with what we’ve shared.