by Paul Sullivan
Last Updated January 19, 2019
Now that you’ve seen our clamp meter reviews, you still may have some questions about the product itself. Clamp meters are invaluable in the workshop, but understanding how they work and what features to look for can really help you as you work. In this buyer’s guide section, which is designed to supplement our reviews, we’re going to explain more in-depth how these devices work and what you should be looking out for.
A clamp meter, which is also called clamp-on ammeter, tests electric currents in a few different ways using a clamp mechanism that you place in the middle of the wire. As we’ve explained, these products work similar to multimeters; in fact, there are multimeters with clamp attachments. These products use transformer action to measure AC currents, but what about DC?
Nowadays, there are many products on the market that can measure both AC and DC voltages, but there are only a few that can measure both currents because DC and AC have different properties.
AC settings on a clamp meter measure the fluctuation of the magnetic field and convert those fluctuations to amp readouts on a digital LCD screen. DC, on the other hand, is dependent on the Hall Effect and measures voltage difference in order to determine the amperage of the current.
When you’re measuring current, you’re measuring how a charge is flowing. When you’re measuring voltage, you’re measuring the difference in charge between two different points. As mentioned, there are many products that can measure both voltages but fewer that can measure both types of current.
To understand how each works for current is relatively simple: AC voltage is the type of current that would be created in a generator that has a distribution system, and DC voltage is primarily measured from the type of current that is generated in a battery. Effectively, you can measure AC voltage using a wire that’s linked into a socket in your home, and you can measure DC voltage by using a wire that powers your car stereo from its battery.
With a multimeter, there’s an inherent danger because there’s a lot of exposed metals and wiring when you’re trying to get an AC or DC reading. Even when you’re testing DC voltage, you can easily cause a spark if you mix up the leads of the multimeter. If you’re measuring the AC voltage of a socket, you’re exposing yourself to potentially deadly amounts of electricity, so extra care is certainly required.
When you’re using a clamp meter on the other hand, you can use a wire that’s coming from the outlet to measure the outlet’s current flow. This device doesn’t require leads and only requires you to place the clamp around the cable or wire. With a multimeter, you might have to cut wires, so with a clamp meter there’s much less chance of electrocution.
Since you won’t be working with leads and you won’t have to cut any wires, clamp meters have a tendency to be much quicker to use than standard multimeters. You simply clamp around the testing wire, get your reading, and move on to the next part of the job. They are also known to be very accurate, and if you know how to read one properly, you can easily diagnose problems.
A good clamp meter can be a cheap and easy tool to use when you need to measure the voltage of an electrical current. They are often digital, have clear and accurate displays, and are much safer in comparison to standard multimeters.
The products that we’ve selected all have a lot of great voltage and amp measurement value, so select the one that best meets your needs. If you prefer a different product, read our buyer’s guide in order to find the best product for you.
When it comes to multi and clamp meters, Fluke is definitely a market leader, and this Fluke 323 clamp meter, which measures AC current, Illustrates why Fluke products are valued. It has a large and easy-to-read LCD, and it has a simple design for ease of use.
Unfortunately, while this Fluke clamp meter will test DC voltage, it doesn’t measure DC current. Also, the leads that Fluke has provided have a tendency to slip out.
Fluke has included True RMS technology to ensure that all readouts are accurate. Additionally, this product contains a continuity sensor.
If you need a quality AC clamp meter that will stand up to just about any job, this Fluke product is a good option. Fluke has designed it to be easy to use, and it’s very accurate.
Another True RMS product, this Uni-T brand product has some excellent functionality and accuracy that rivals the Fluke device. This is also a very small and ergonomic clamp meter; it’ll fit in your hand easily and can be used for hours.
For whatever reason, Uni-T ships this with a Chinese manual so you’ll have to download instructions on the internet.
Direct current readouts on this product aren’t very good when it comes to accuracy. It’s better than a cheap product, but you’ll have a better time measuring alternating current.
Unlike the Fluke product, this unit can measure both alternating and direct current, so you get some extra functionality when you need it. It’s also designed to be more compact so it’ll fit in a tool belt with ease.
For those looking for a fairly versatile and compact product, this meter from Uni-T is one of the top products on the market. In fact, this may be one of the best clamp meters for ease of use.
This Klein Tools clamp meter is fairly versatile. Not only does it read both alternating and direct currents, but it also has a thermocouple for temperature readouts.
Additionally, the clamp switch is very ergonomic and comfortable, and the action on the clamp itself is smooth. It also comes with test leads.
The first thing that you might notice about this meter is that it’s a bit on the expensive side. It’s also relatively slow when it comes to screen update time. In addition, Klein has removed the lead holders that have existed on the back of the meter in previous versions.
Sometimes when you’re taking a reading, you can get sudden spikes on your clamp meter readout. These ghost voltages are annoying and problematic, but fortunately, this product from Klein Tools has a low impedance that can reduce the incidence of these stray readouts.
While it is expensive, this Klein Tools product functions fairly reliably. It can measure both types of current and also has protection against stray voltages.
Not only does this product measure alternating current, but it also can measure the frequency of the signal. It packs in a fairly easy to use design and includes leads and a carrying case so you can go out and measure with confidence.
At only seven ounces, this product fits neatly in a tool belt and is very light.
This product lacks a peak hold function, which means that it isn’t great for a starter motor test. This means that finding the peak current can be difficult. In addition, this product only measures alternating current, so if you need direct current measurements, you’ll have to purchase another product.
This clamp meter’s display is fairly well-designed; it not only has a large LCD readout area, but it also has backlighting for dimmer work areas.
In addition, the product has a data hold feature that will let you call up previously recorded data when you need it.
With the ability to measure both alternating and direct voltages up to 600V, this AC current product is fairly versatile. It also has one of the best fully-featured displays in comparison to many of the other products on the market.
Another Klein Tool, the CL312’s best feature is its auto-ranging technology that is designed to provide some excellent accuracy in your meter readouts.
This is also another product that incorporates a thermocouple probe that will allow you to also take temperature measurements. When it comes to general functionality, this clamp meter is designed to only provide alternating current readings.
This is a meter that is best used for non-professional jobs around the house because the leads aren’t high-grade enough for extended use. Additionally, the carrying bag that comes with the product is a bit on the flimsy side, so don’t expect it to last as long as the meter itself.
This clamp meter has some very convenient features, such as its low-battery indicator. It’s also very tough; you can drop this device from a full meter to the ground and it won’t suffer much damage.
It also has a high-quality display with a good amount of backlighting and is designed with easy-to-read amp measurements.
While they could have included a better carrying pouch, the Klein Tools CL312 is a good starter clamp meter that is best for those that need robustness and versatility. It even has easy to use dials and buttons that make minutes adjustments very easy to implement.
This product is one of the best digital clamp meters for display because it has two readouts. This will give you more stats about the item that you’re scanning so you can have more accuracy.
Unfortunately, the clamp on this meter has a tendency to be a little too bulky. If you’re working in darkened areas, this product’s excellent display is missing backlighting, so it’s best to have a light source.
If you need durability, this product can take a ding or two. UEi has provided a fairly versatile and durable carrying case with this product, and there are also storage areas for the test leads, which is convenient.
This clamp meter has a good amount of versatility for most jobs, though its clamp can be slightly too bulky. Regardless, you can get some of the best electrical testing done with the DL369.
Frequently asked questions
Depends from meter to meter. Generally, you can, but there are some clamp meters that don’t have that possibility.
Clamp meters are as safe as multimeters are. The tipping point that makes clamp meters safer than multimeters is the non-contact voltage measuring function. Since it requires no contact with the wires, there is less chance that the person using the meter will be injured.