GTC CM100 1 mA to 100 Amps AC/DC Low Current Clamp Meter by General Technologies Corp

Extremely Accurate- I was a little reluctant to purchase this at first. Price is a little steep, I have a couple of others, 1 digital and a few that have a needle read out. My wife’s car had a “phantom draw” and using this meter and a few of the additional accessories I purchased separately I was able to isolate the issue. The “authorized dealer” missed the problem on several occasions. I have since found several other uses for the meter and won’t be turning back to the old meters. I have a digital scientific power supply and tested this meter for accuracy. It beat the other 5 meters hands down. It was spot on every time!

Very accurate down to 1ma level. When measuring the DC current combined with peak function, you need follow the current flow direction mark on the clamp side, if flow direction reversed, then you will always get "0" as peak value because the real peak value is recorded as negative,then you will think the peak funtion is not working.( this is also true for dc vlotage measuremet with test lead) Its response time is quick. The zero function work fast and accurate. Only one issue: the DC voltage measuremet get 0.2 volt difference (less) in negative reading if you reverse the two test leads to measre.(like 1.5 v and -1.3 v which shouel be -1.5 v) I tried two meters and they act the same. I may live with this and remember to keep the low DC voltage measurment in positive side. Amazon even send me the new second meter before I return the first one. Definitely a great buy, if you wnat measure low accurate dc or ac current with clamp, and need peak function.

DO NOT SELL THIS METER SHORT. Since receiving the meter, I have measured the current on all of my home AC curcuit breakers. I even measured the current on a 1.5vdc toy motor, I measured the difference in current between an edison base floressant light bulb verses the old incondesent type . I almost forgot, I measured the sleep current on both of my cars. This meter is not however not the best at measuring very low ohm values. For all around home and handyman use (IT IS A KEEPER). I like it. It is made by (GTC General Techinologies Corp. out of Canada.)

Seems to do what it's supposed to do. The function "Thumbwheel" is pretty darn stiff, as compared to a couple of Mastect's I have here .. I guess that's a good thing, depending on your preference .. turning it On may be a two-hand operation .. depending on your manual dexterity and digit strength. It lacks an LCD back-light function, or a "Target" LED. The "Volts" screen-printing should have been done in a more contrasting color .. this is a "Mature" product, but this has still been neglected. As typical with all Hall-Effect devices, it has difficulty in discriminating between what would be a True RMS (pure D.C.) current, and any residual A.C. component from an A.C. powered battery charging system, so it kinda goes a little nuts when my inverter/charger is pumping through 70 amps (56 volts during bulk). Most accurate readings are found during discharge, with the PV panels Off, to avoid any A.C. ripple from the charge controller. It will clamp nicely over 2 gauge welding cable, but you will need to remove a short length of insulation from 00 gauge for it to fit over the cable .. re-cover with thin electrical tape. This meter will accommodate maybe 95% of my current measuring tasks .. everything but engine start and glow-plugs .. the Mastec's linked here are good for 600 amps. Although a bit pricey, I do recommend this meter for both Off-Grid systems, and automotive diagnostics. Cheers! Mastech MS2108 True-RMS AC/DC Clamp Meter with Inrush Current Measurement

This meter is slightly temperature sensitive. If you leave it on for 2 - 3 minutes and re-zero it, it will not drift more than 1 ma. If you pick up the meter it will drift from the heat of your hand, if you put it back down, it will return to 0ma. So I hold the meter for a few minutes, re-zero and take the measurement, it will drift almost nothing. If it does, just subtract the drift from your reading. Take into account the sign of the drift. I have a few other expensive meters that do the same thing at very low ranges and use them as I described above. Even very expensive other meters will drift at very low ranges whether they measure capacitance, inductance, milliohms, or field strength, volts/amps/resistance or whatever. This meter is so sensitive to extremely small magnetic fields that spacial orientation to earth's magnetic field affects these kinds of meters. Zero the meter near the measurement location, move the meter to attach it around the wire, but don't change its spacial orientation by twisting, rotating it, just move it forward to the wire. It would be better to hold the meter close to the wire, zero the meter, then hold meter still and move wire to jaws. Use this meter with common sense, and it will work very well.

I never heard of this company, but they are based out of Canada. Figured how bad could it be. The fit and finish is great. I like the resolution of this meter. I will use this for automotive current draw. The wire opening is really small, probably how they can get good resolution and increased accuracy. LCD is easy to read and it has Min/Max function.

I am a seasoned electronic tech and avid Do It Yourselfer. I tested the accuracy of the clamp-on Amp meter and it is quite good for the price. I have already used it on some automotive projects and look forward to using it on my future electronic projects. DC clamp-on current meters are great for when you want to measure Amperes flowing through a wire but don't want to cut it to insert a "classic" Amp meter in series. The Ohm and Voltmeter ranges on this meter leave a lot to be desired. Don't buy this thing if you need anything but the basics on resistance and voltage measurements. That said, the clamp on DC Amp meter is well worth the price of the entire meter, even if you never use the Ohms and Volts scales.

Tried to return this item as it was specifically purchased for 4 - 20 mA readings and is not even close to accurate. It was not picked up at my facility like it was supposed to be and when taken to a authorized return establishment they could not process the documentation i was given.

Day after receiving had a current draw killing battery. Measured 3 times( remove clamp and reset zero). All 3 times 818 milliamps. Found a rear door not latched properly. Draw down to 240 milliamps. But I saw interior light on after doors closed. Turned off lamp. Draw 25 milliamps. Reset clamp. Checked again. 25 milliamps. Perfect. 2 days ago had another draw on a ford escape. Toggling draw between 900 milliamps and 5.2 amps. Checked rear wiper motor operation and it’s seized like they all do. Unplugged motor and draw now 135 milliamps. Takes an hour for all modules to go to sleep. Came back 45 minutes later and measured 47 milliamps. Awesome. Was blown away that something this cheap can accurately measure 25 milliamps. No more connecting voltmeter in series and possibly blowing the internal fuse. Highly recommend for automotive current draw testing. Everyone in garage impressed with it’s continuous accuracy.

Fast delivery and exactly what he wanted.

excelente herramienta para diagnostico de consumo de amperaje

Neat unit, small, sufficient ranges, the only low current clamp meter I could find to measure at milli-amp level at a reasonable price.

If there's a Tool Of The Year award, this one's a top contender. Imagine being able to pull a wire out of a fifty wire automotive harness, and measure if there's DC current flowing through that wire and if so - how much down to a couple of mA. And do ALL of this without puncturing the insulation on the wire! A comparable tool from a name brand like Fluke costs THOUSANDS of dollars.