When using my Clamp meter, i notice that it had a range in the upper 90's instead of 120 on a 14 ga - 15 amp circuit breaker. Is that low or is it because i have close to 20 duplex outlets (for now connected to it-planning to change that). Mostly tv and a computer and outlets and lights. Is that common? And if not why am i getting in the high 90's? Or should you always get between 110-120? Second questions should there be any voltage in traveler wires in a 3 way 14 ga 15 amp circuit connecting two lights?

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    Are you sure the meter is good? Are the batteries in the meter fresh? How exactly are you measuring the voltage (between what points in the circuit)?
    – Tester101
    Commented Apr 26, 2017 at 10:50
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    I agree with the above comments 1 more question is your meter a true RMS meter? My clamp meters have probes for measuring voltage is this the type you have? non contact voltage detection is sketchy at best. as far as the travelers yes there should be power present on 1 of the wires but the other may show induced voltages as mentioned above. Check the voltage at the panel I have found some panels FPE & zinsco to have higher than normal voltage drop in the past. 20 outlets is a lot but if not loaded beyond 15 amps the voltage should not drop as far as you are seeing.
    – Ed Beal
    Commented Apr 26, 2017 at 13:03
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    I have never heard of quantitative measurement of voltage (more properly known as "electric potential difference") other than with probes that contact the conductor. I am more than willing to be corrected, but my understanding is that if the meter is only clamped around a wire it can measure electric current (amps) flowing through the wire, but not the potential difference (volts) between that wire and neutral or ground. Maybe this clamp has little spikes which pierce the insulation on the wire and make contact with the conductor and the meter is connected to ground? Is that it? Commented Apr 26, 2017 at 14:15
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    @larrypinsky You're doing it wrong. You have to use the probes to test voltage. Please see the Operating Instructions for the Klein Tools® CL600 (PDF). Specifically, check the section on measuring voltage
    – Tester101
    Commented Apr 26, 2017 at 14:35
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    @jim Stewart there are non contact high voltage meters we use on ultra high voltages 180kv used on ion implanters, I have seen lower voltage models but they are not so good with a loaded circuit so they do exist. Note they do need a ground reference and the measurement is a specific distance from the conductor or corona ball.
    – Ed Beal
    Commented Apr 26, 2017 at 18:40

1 Answer 1


Larry from the online info on this meter

Klein Tools CL600 is an automatically ranging true root mean square (TRMS) digital clamp-meter that measures AC current via the clamp, and measures AC/DC voltage, resistance, continuity, and tests diodes via test-leads.

Do you see that the clamp is for AC current measurement. The clamp cannot give a voltage reading. Voltage reading is by the probes.

  • I understand that now. And truthfully i did use the probes before for ac voltage on receptacles before i changed then to tamper resistant. Never tried it on wires which i should had read and as you indicated. The clamp meter was originally for testing ac voltage (which i was wrong) and amperage. As i said, i misunderstood the clamp part entirely. Is there a major difference between trms and rms for my purpose? Or should i had paid a few bucks more and got a true rms? Again thank you. I want to hide my head in the sand. Hope others learn from my mistake. Commented Apr 26, 2017 at 22:39
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    For your purposes I doubt there would be any differences between trms and rms, but I thought you meter read trms? Don't you have the CL600? Commented Apr 27, 2017 at 0:29
  • Yes i do have the klein cl600 and truthfully it has helped me especially with continuity and traveler wires (shut off power) utilizing the probes to locating the other set of traveler wires at the other end. It also helped me originally to check my old receptacles using the probes fir determining ac voltage.. I truly do see now that the clamp purpose is only for amperage period which included utilizing a splitter that i purchase for certain appliances. I found it helpful on the most part except that major screw up with the clamp usage. Again thank you for breaking it down. It says true rms. Commented Apr 27, 2017 at 2:35
  • trms as you stated Commented Apr 27, 2017 at 2:46

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