June 14, 2021

Professional Tool Reviews for Pros

Klein 400A Digital Clamp Meter Review CL380

Klein CL380 clamp meter hard jaws
PTR Review
  • Pro Rating 9.5

The Klein Tools 400A Digital Clamp Meter offers all the standard features Pros expect but differentiates itself with an excellent reverse-contrast LCD display that's very easy to see in all light conditions. If you need an all-around clamp meter and prefer hard jaws, this CL380's price and performance make it a serious contender.

Overall Score 9.5 (out of 10)

The hard-jawed Klein 400A Digital Clamp Meter CL380 offers standard professional features and a remarkably easy-to-read reverse-contrast LCD display. It’s been assisting me with service work including today’s task: installing a new circuit for a dryer in a mobile home.


  • Reverse-contrast LCD display is very easy to read in all light conditions
  • Includes all standard functions needed to perform most service and installation work
  • A great price


  • No significant downsides


This Klein Tools meter reliably performs all the functions a professional electrician needs on the job site. The outstanding feature of its otherwise standard—but comprehensive—set is the reverse contrast LCD screen. I found it easier to read than a typical meter’s screen in every lighting condition. If I had to decide among several comparable meters, this feature alone would tip the balance toward the Klein. Plus, it’s got a great price!

Klein 400A Digital Clamp Meter Performance

Reverse Your Contrast

I was recently called out to install a dryer circuit in a mobile home. The small panel was a Frankenstein-ed mess of wires in a bedroom closet. But it turned out to be a great place to highlight the Klein 400A Digital Clamp Meter’s excellent reverse contrast LCD screen as well as the challenge of a hard-jawed meter in a tight, messy panel.

Klein Tools 400A Clamp Meter panel

First, the LCD display. The white digits on black background almost jump off the screen. I didn’t have to squint, and I didn’t need a backlight like with a traditional LCD display. Likewise, the screen was just as easy to read in bright light. I began to wish all my meters’ displays offered reverse contrasts!

Klein 400A Clamp Meter display

Electricity’s Open Jaws

The hard-jaws of the Klein Tools 400A Digital Clamp Meter allow easy, one-handed operation in large, commercial panels. However, few of us Pros have the luxury of working solely on such panels with neat installation and room to close the jaws around cables and wires. Service work, especially the residential kind, often means you’re dealing with a situation like today’s panel. And this one was exceedingly messy.

Klein 400A Digital Clamp Meter

I certainly can’t ding the Klein CL380 for having hard jaws because they work quite well as designed. But it reminds me of the advantages of flexible coil meters like the Klein Flexible Amp Meter and Greenlee CMF-110 Meter that I recently reviewed. These coils allow greater access in tight and messy panels where hard jaws can’t go.  You’ll lose the one-handed advantage but gain the ability to take more measurements.

Klein CL380 meter mode dial

Klein CL380 Digital Clamp Meter Price

The Klein 400A digital clamp meter prices out at what I’d call a great value: $71.49. Here’s a quick sampling of the large, competitive field of meters:

The Bottom Line

The Klein Tools 400A digital clamp meter offers all the standard features Pros expect. However, it differentiates itself with an excellent reverse-contrast LCD display that proved very easy to see in all light conditions. If you need an all-around clamp meter and prefer hard jaws, this CL380’s price and performance make it a serious contender.

Klein 400A Digital Clamp Meter Specifications

  • Model: Klein CL380
  • Power: 3 x AAA (included)
  • Auto-power off
  • Jaw size (max): 1.8 in. (45.72 mm)
  • Drop protection: 6.6 ft. (2 m)
  • Display: 4000 count reverse contrast LCD
  • Functions: NCVT, DC micro-amps, temperature, hold, max/min, rel/zer
  • Voltage: 600 VAC/DC
  • Frequency: 10 Hz to 60 kHz for 8 V to 220VAC RMS
  • Current: 400 A AC/DC
  • Capacitance: 4000 µF
  • Ohms (resistance): Range 40 MΩ
  • DC polarity indicator
  • AC voltage: 600 V
  • DC voltage: 600 V
  • DC micro-amp: 200 μA
  • Temperature range: -40° F to 1832° F (-40° C to 1000° C)
  • Standard: CAT III 600V, Class 2, double insulation safety rating
  • Included: Carrying case, test leads, thermocouple probe, instruction manual and 3 x AAA batteries
  • Dimensions (LxHxW): 8.66 in. (220 mm) x 3.03 in. (77 mm) x 1.61 in. (41 mm)
  • Weight: 8.3 oz (236 g)
  • Price: $71.49

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