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If you are going to be working in HVAC, then a good clamp meter is an essential part of your toolbox. In this article, we will help you find the best clamp meter for HVAC, discuss what makes a good clamp meter, some features of clamp meters, and review a few different clamp meters.
List of the Best Clamp Meters for HVAC
Klein Tools CL800
Why Use a Clamp Meter?
A clamp meter is used primarily to measure the current going through an electrical circuit. A clamp meter works by measuring the magnetic field that is generated when electrical current flows through a wire.
Most clamp meters on the market today also include features of a digital multimeter (DMM), such as voltage, resistance, and continuity detection. In this clamp meter review, we’ll discuss factors to consider when purchasing a clamp meter, and compare a few different clamp meters.
Clamp meters have become indispensable tools for two reasons:
Clamp meters allow you to measure current without coming into contact with bare wire. This means that you don’t need to attempt risky rewiring of circuits to get a current reading.
Clamp meters are capable of measuring high amount of current without even coming into contact with the wire. In fact, the circuit does not even need to be disconnected in order to be measured by a clamp meter. The old method of putting a test meter in series with the circuit are long gone.
That being said, not all clamp meters are created equal. Some clamp meters are capable of measuring high amounts of current, while others are better for measuring low amount. While most clamp meters can measure alternating current (AC), some clamp meters can measure direct current (DC) as well.
All clamp meters incorporate a current-sensing jaw, a selector switch (for turning the meter on/off and changing modes), and a screen to readout the current measurement. Some extra features that some of the nicer clamp meters include are: a backlight for the screen, voltage/resistance/continuity testing, and non-contact voltage testing (NCV).
Types of Clamp Meters
There are three types of clamp meters that are used today:
1. Current Transformer
This is the most common type of clamp meter. This type of clamp meter relies on magnetic induction to measure AC current. When the clamp meter is placed around a wire, the electric current flowing through the wire produces a magnetic field that is detected by the transformer in the clamp meter. If a clamp meter can only measure AC current, then it likely has a current transformer sensor.
2. Hall Effect
These types of clamp meters are able to measure both AC and DC current. Hall effect clamp meters work by producing a voltage that is proportional to the magnetic field generated due to current flow in the wire. If a clamp meter can measure both AC and DC current, then it likely has a hall effect sensor.
3. Rogowski Coil
These types of coils are used in flexible clamp meters. Rogowski coils can only measure AC current and are good for measuring large amounts of current and measuring current in tight spaces. Rogowski coil meters are seldom used in day-to-day practice, and are usually reserved for specialized applications. If a clamp meter is comprised of a cable, then it likely has a Rogowski coil sensor.
Factors to consider when selecting a clamp meter
You should choose your clamp meter based on your needs. The current transformer and hall effect clamp meters usually look the same, with the main difference being that hall effect clamp meters can measure both AC and DC current instead of only AC current. For measuring large amounts of current, rogowski coils can plug directly into the bottom of some clamp meters.
Here are a few factors to consider when selecting a clamp meter:
What current ranges will you be measuring? Most clamp meters can read up to 400 A, so unless you are using the clamp motor to read very large pieces of equipment, then current measurement range will not be an issue.
Will you be measuring in tight spaces? Some clamp meters are large and bulky, and can be hard to maneuver in tight spaces. Will the size of the jaw matter? You may need your clamp meter to measure large wires. Alternatively, a clamp meter with a small jaw is very good at maneuvering in small enclosures where wires are tightly spaced.
Will you be using the clamp meter in a dark place? Some clamp meters have a backlight for the screen. Some clamp meters even have built-in flashlight for illuminating small work areas.
Are you using this meter for any type of official measurement? Does it need to be calibrated? For an extra price, some clamp meters can be purchased with a calibration certificate.
Do you need your clamp meter to do more than just measure AC amps? Most clamp meters on the market today incorporate features of multimeters, such as voltage, resistance, and continuity testing. Also, if you are measuring current from non-sinusoidal sources (such as a VFD), then you will want to get a true-RMS clamp meter.
What kind of accessories are available for this clamp meter? There are a variety of accessories available for some clamp meters, adding function and versatility to the product. Some clamp meters even come with temperature sensors than can be plugged into the clamp meter.
What type of work will you be doing? Does the clamp meter need to have a safety rating? What CAT III and CAT IV voltages does the meter need to be rated for? CAT III rating describes the voltage limit to take measurements at the electrical distribution panel. CAT IV rating describes the voltage limit to take measurements at the electrical utility connection.
Do you need your clamp meter to have a warranty? Most clamp meters come with a two-year warranty, some come with a shorter warranty period. Also, when making a warranty claim, some clamp meter manufacturers are known for being easier to work with than others.
Clamp Meter Reviews
Klein Tools has been around since 1857 and is known primarily for their hand tools, which can be found in the tool pouches of nearly every electrician across America. Klein Tools also makes clamp meters, and the Klein Tools CL800 is a True-RMS clamp meter that also incorporates detachable test-leads and a thermocouple for temperature measurement.
This clamp meter is very durable and includes a rubberized grip for extra protection. It also has tons of features, including many things not found in other clamp meters such as a non-contact voltage detector and a work light.
The CL800 also features a low impedance (LoZ) mode for detection of ghost voltages. This is the only clamp meter in our review that can measure DC amps with a clamp.
The CL800 also has the highest safety ratings out of all of the clamp meters in our round up, with CAT III 1000V and CAT IV 600V ratings. Overall, it is a high quality clamp meter and has the most features out of all of the clamp meters in this review.
When people start talking about quality clamp meters and multimeters, the name Fluke comes up a lot. The Fluke 323 True-RMS Clamp Meter is the no-BS clamp meter for someone who needs true-RMS sensing to measure AC current.
It is designed to be a solid tool, with basic multimeter functions. Because of its simplicity, is easy to use, especially with its large display. This clamp meter also comes with two test leads and a soft carrying case – perfect for protecting against getting banged up from being in a toolbox.
All in all, the Fluke 323 is a solid choice for a technician that needs a no-frills, reliable meter for reading AC currents.
The Ideal 61-744 is a compact meter that includes non-contact voltage detection (NCV), among many other features usually only found in more expensive meters. It is one of the best-valued meters in our round-up since it has high range and accuracy usually only found in more expensive meters.
Etekcity is an ecommerce retailer that is known for their consumer electronics. Because of this, their MSR-C600 clamp meter is targeted more toward the weekend-warrior, rather than the full-time tradesman. However, the MSR-C600 brings great value to your tool arsenal if you are looking for a capable clamp meter on a budget.
The MSR-C600 has a compact clamp that is perfect for reaching into tight spaces. It also has a diode tester – something that is not found on many clamp meters.
All in all, this meter is good for general purpose use, but not the best choice if you need extra features or a high safety rating.
UEi is a company known for manufacturing a variety of test instruments. The brand has gained notoriety over the last few years for producing quality, feature-rich test instruments for an affordable price. The DL369 clamp meter is a testament to this, providing a variety of features that are commonly found on more expensive clamp meters.
The DL369 meter has a crazy amount of features for its price point. For one, it can measure capacitance, AC frequency, and non-contact voltage – all of these things are not usually found even on more expensive meters.
The response time on this meter is super quick to take readings. It also has the best warranty of any meter in this round up – a 3-year manufacturer’s warranty.
Clamp Meter Comparison Table
2% +/- 5 digits
2% +/- 5 digits
1.7% +/- 6 digits
1.5% +/- 5 digits
1.9% +/- 8 digits
CAT III 1000V
CAT III 600V
CAT III 600V
CAT II 600V
CAT III 600V
Clamp Meter Measurement Types
Most clamp meters don’t only measure AC amps. In fact, almost every clamp meter on the market today is a full-fledged multimeter that is capable of measuring many different things such as voltage, resistance, and continuity.
Here are a few different features that you’ll find on clamp meters:
Most clamp meters are able to measure AC voltage using their included test leads. When taking voltage readings, be sure that your leads are in good shape with no exposed wires showing. Also make sure to never cross your leads!
Clamp meters are primarily used to measure AC amps. Therefore, every clamp meter is capable of measuring AC amps. Where they differ is in the range and accuracy of taking such measurements.
Most clamp meters are able to measure DC voltage using their included test leads. When taking voltage readings, be sure that your leads are in good shape with no exposed wires showing. Also make sure to never cross your leads!
Most clamp meters are able to measure DC amps using their included test leads. But to do this, you must disconnect the circuit and wire the clamp meter’s test leads in series with the load. This is simply not practical or possible in many situations.
Some clamp meters are able to measure DC amps using the clamp. This has one big advantage, in that you don’t need to disconnect any circuits to get accurate DC amps readings. Meters with this capability are highly sought after and have a price to reflect that.
Most clamp meters are able to measure resistance using their included test leads. Measuring resistance is an essential part of diagnosing many electronics, from small circuits to large motors.
Most clamp meters are able to measure continuity with their included test leads. Continuity is basically a resistance measurement that will sound a buzzer if a short circuit is detected.
Measuring continuity is useful to trace wires and figuring out how a circuit is wired without physically finding the path of wires.
Measuring capacitance is a slick feature for a clamp meter. Most clamp meters are not able to measure capacitance.
Measuring capacitance is useful for diagnosing capacitors and seeing if they are bad. Capacitors are found in all sorts of HVAC equipment, from fans to compressors. Capacitance measurement is an essential part of any HVAC technician’s toolbox, so it is a good bonus to have on your clamp meter.
Non-Contact Voltage (NCV)
A non-contact voltage detector emits a sound when AC voltage is detected nearby. This is useful for verifying if a circuit is live or not.
Most clamp meters do not have NCV testing, so it is a nice feature to have.
Some clamp meters include a small LED light on them that illuminates the area where you are working. This is useful for helping you clamp a wire in dark breaker panels and junction boxes.
Thermocouple (Temperature Sensor)
Some HVAC-oriented clamp meters include a thermocouple that you can plug into the clamp meter to measure temperature.
Since working on HVAC equipment requires measuring temperatures, it is nice to have a clamp meter that is capable of doing so.
Any experienced HVAC technician will tell you that a clamp meter is an invaluable tool. Since most clamp meters nowadays come with vast features, it is often more practical to just carry around a clamp meter for all of your electrical testing needs. There are a variety of different clamp meters available at different price points, so be sure to weigh all of your options before making a choice.