Klein Cl220

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The Klein CL220 is an auto-ranging TRMS clamp meter that Klein describes as a 400 A AC clamp meter with temperature measurement. It reads AC current through the clamp, AC and DC voltage, resistance and continuity through the test leads, and temperature through a K-type thermocouple. Klein’s instruction manual lists CAT III 600V, class 2 and double insulation. This explainer covers those functions, the safe-use points in the instructions, the one listing conflict we found, and what to confirm before buying the CL220.

Quick answer

The CL220 is an automatically ranging TRMS clamp meter, per Klein’s instruction manual.
Klein lists the safety rating as CAT III 600V, class 2, double insulation, and the manual gives maximum input as 600V AC RMS or 600V DC.
The clamp reads AC current up to 400 A, and the manual lists a non-contact voltage (NCVT) function.
The sources disagree on whether the CL220 has a DC microamp function. Check the label and the manual for the unit you buy.

What the CL220 measures

Klein’s manual describes the CL220 as a meter that measures AC current via the clamp, AC and DC voltage, resistance and continuity via the test leads, and temperature via a thermocouple probe. The product page lists the same set, with NCVT and TRMS in the functions list. The clamp covers the AC current job. The leads cover the voltage, resistance and continuity jobs. The thermocouple covers temperature.

The auto-ranging feature selects the measurement range for you, which is useful when you do not know the expected reading. The manual also includes a range-hold function, so you can lock the range when you want the meter to stay on one scale. Use range hold when a reading jumps between ranges and you want to watch one value.

The product page gives the jaw opening as 1.6 inches, and the manual describes the clamp as a 400A AC meter. Measure the conductor before you plan the reading, because the jaw size decides which cables fit. The product page also gives the temperature range as -40° to 1832°F, or -40° to 1000°C. Those figures are the range the page shows for the temperature function, not a guarantee for every probe placement.

Ratings in the manufacturer documents

The Klein instruction manual gives the safety rating as CAT III 600V, class 2, double insulation. The product page repeats the rating as CATIII 600V, Class 2, Double Insulation Safety Rating, CE Certified. The manual’s general specifications give maximum input as 600V AC RMS or 600V DC. Those two numbers set the voltage limit for the leads.

The manual describes CAT III as a measurement category for test and measuring circuits connected to the distribution part of an installation. A category tells you what the meter is built for. It does not tell you that every circuit at that level is safe to open. Panel, service and uncertain live-circuit work belongs to a licensed electrician.

A listing conflict to check

Klein’s clamp meter brochure (Cat. No. 82908) gives the CL220 the product title “HVAC 400A AC TRMS Clamp Meter with Temperature and DC Micro Amp.” The Klein product page lists the CL220 functions as TRMS, AC current, NCVT, AC/DC voltage, resistance, continuity and temperature, with no DC microamp entry. The instruction manual we opened does not list a DC microamp function either. We therefore do not state that the CL220 measures DC microamps. If you need that function, check the printed label and the manual that ships with the unit.

This conflict is the most useful thing to check before buying. A product title can include a feature that the manual does not describe. The manual is the document that governs how the meter works, so read it before you rely on any function.

Safe-use points from the instructions

Do not operate the meter with the battery door removed. The manual says this avoids the risk of electric shock.
Verify the NCV function before and after each use. The manual asks you to test the NCVT on a known working source before and after use.
Read the NCV limits. The manual says the NCV tester will not detect voltage in some conditions, and it may not detect voltage in others. Treat a “no reading” as no information about the circuit.
Use leads rated for the job. The manual calls for test leads with a voltage rating of CAT III 600V or better.
Stay within the maximum input. The manual lists 600V AC RMS or 600V DC as the maximum input.

Mains electricity can kill. The CL220 is a clamp meter, and a clamp meter does not make a live conductor safe to open. Use the NCV function as a screen, use the meter reading as the measurement, and leave panel and service work to a licensed electrician.

Power and auto power-off

The manual says the meter powers down automatically after approximately 10 minutes of inactivity. That is the auto power-off feature, and it saves battery life between jobs. If the meter switches off during a long session, check for auto power-off before you assume a fault, because the manual describes that feature by name.

Who the CL220 suits

The CL220 fits a technician or a serious DIYer who needs AC current through a clamp, with voltage, resistance and continuity on the same meter and a temperature input for a probe. A household user who only checks a single appliance cord may find a simpler clamp covers the task. The CL220 makes the most sense when you want the clamp, the leads and the thermocouple in one case.

Before you buy: a short checklist

Confirm the DC function. The brochure title and the product page disagree. Read the printed label before you buy.
Confirm the category. The manual states CAT III 600V, class 2, double insulation.
Measure the cable. The product page gives a 1.6-inch jaw opening.
Plan for the NCV check. Keep a known live source handy for the before-and-after test the manual describes.
Plan the thermocouple. The temperature function uses a K-type thermocouple, so check that the included probe matches that type.
Check the drop protection. The manual gives 6.6 ft (2 m) drop protection.

How we chose

This explainer uses the Klein CL220 instruction manual, the Klein product page for the CL220 and the Klein clamp meter brochure, all opened on 2026-10-27. We did not compare the CL220 with other clamp meters, and we did not rank it. We used the brochure to find the listing conflict on DC microamps, and we kept it out of the body where the manual gives no support.

What we could not verify

The sources we opened do not give us a DC microamp specification for the CL220. They do not give a full accuracy table that we can quote here, so we did not repeat accuracy figures. The product page gives the temperature range, but the sources do not state the probe accuracy in a form we can quote. The manual lists 2 m drop protection, so check the manual that ships with your unit if that figure matters to you.

Mistakes to avoid

Assuming a DC microamp function from the title. The sources disagree, so check the label and manual.
Treating a no-reading NCV test as proof of no voltage. The manual lists conditions where the NCV tester will not detect voltage.
Operating with the battery door off. The manual says this is a shock risk.
Using the wrong probe type. The meter’s temperature input is described as K-type, so a probe of another type will not match the function.

FAQ

Is the Klein CL220 rated CAT III 600V?

The instruction manual states CAT III 600V, class 2, double insulation. The product page gives the same rating.

Does the CL220 measure DC current through the clamp?

The manual we opened describes AC current through the clamp. Do not assume a DC clamp function. The sources also disagree on DC microamps, so check the label and manual before buying.

What is the jaw opening?

The product page gives 1.6 inches. Measure your conductor before you clamp it.

Does the meter turn off by itself?

The manual says auto power-off occurs after approximately 10 minutes of inactivity.

Bottom line

The Klein CL220 is an auto-ranging TRMS clamp meter with a 400 A AC clamp, a built-in NCV function, a thermocouple input and a CAT III 600V rating in its manual. Confirm the DC microamp question before you buy, do the NCV check before and after each use, and leave panel and service work to a licensed electrician. For more on clamp meter types, read Best Clamp Meter: AC Current, True RMS and Logging Compared and Best Digital Clamp Meters: 4 Picks Compared.

For the basic steps before any clamp reading, read How to Use a Clamp Meter Safely, Step by Step, then return to the checklist above.

Sources

Klein Tools, “CL220 Instruction Manual” (English), 400A AC Auto-Ranging TRMS Clamp Meter. https://data.kleintools.com/sites/all/product_assets/documents/instructions/klein/CL220-1390364ART%20-%20WEB.pdf (opened 2026-10-27)
Klein Tools, “Digital Clamp Meter, AC Auto-Ranging 400 Amp with Temp” (CL220) product page. https://www.kleintools.com/catalog/clamp-meters/digital-clamp-meter-ac-auto-ranging-400-amp-temp (opened 2026-10-27)
Klein Tools, clamp meter brochure, Cat. No. 82908. https://data.kleintools.com/sites/all/product_assets/documents/brochures/klein/82908_ClampMeter_SellSheet_WR.pdf (opened 2026-10-27)