Klein Tools CL440 HVAC Clamp Meter

Yes. The CL440 carries a CAT IV 600V and CAT III 750V rating with Class 2 double insulation, which covers service entrance and distribution panel work up to those limits. It measures up to 750V AC and 600V DC. Never put it on a circuit above its category rating.

That's exactly what the DC microamp mode is for. The CL440 reads up to 600 microamps DC through the test leads, in a dedicated mode alongside inrush capture, so you can verify flame rectification signal on a gas furnace without a separate meter.

Temperature is built in. A K-type thermocouple is included and the port reads from -328 to 2462 degrees F. That covers supply and return air splits, line temps, and flue readings without carrying a second instrument.

You get the meter, right-angle input test leads, push-on alligator clips, a K-type thermocouple, a storage pouch, an instruction manual, and 3 AAA batteries. Nothing else is needed to start testing. The Magnetic Hanger, Cat. No. 69417, is sold separately if you want hands-free use inside an air handler or at a panel.

Capacitance measurement goes to 6.000mF (6000 microfarads), which covers typical run and start capacitors on residential and light commercial condensing units. Resistance reads to 60 megohms for winding and ground checks, and there's audible continuity for quick circuit verification.

No. An NCVT is integrated into the clamp jaw of the CL440, so you can sweep for live conductors with the same tool you're metering with. Klein still recommends verifying meter operation on a known live source before each use.

Yes, the backlit 6000-count LCD has a dual V + A function that displays both simultaneously, so you can watch voltage sag while a motor pulls current instead of switching modes. It's auto-ranging TRMS, which matters on variable speed and inverter-driven HVAC loads where a non-TRMS meter reads low. Min/Max and data hold are there for capturing readings in tight spots.

It's rated for a 3.3 foot (1 m) drop and the housing is ABS. At 14.2 oz it's light enough for a pouch, and overall it measures 10.04 x 3.77 x 1.57 inches. Auto power off is included so a meter left on in the bag doesn't kill the AAAs.

Yes. Klein lists Cat. Nos. 69140, 69142, 69144, and 69410 as replacement parts for the CL440, so worn leads, clips, or the thermocouple can be swapped rather than replacing the meter.

Frequency measurement goes to 60 kHz, and duty-cycle testing is included as well. Paired with TRMS current, that covers checking drive output and ECM motor signals on commercial rooftop equipment. There is also a DC polarity indicator and diode test for control board work.