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

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.

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.

This was an awesome purchase.Very Helpful when looking for a mA draw coming from an aftermarket module hidden...The clamp size could be alittle bit bigger, but hey, it fit around the cable size I was working with....

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

Great milliamp meter for DIYing a vehicles electrical system/battery drain. Measurements are consistent and accurate. Easy to use. Money well spent!

This meter is easy to use and works well. Happy with my purchase!

I work at a dealership so my tools stay inside and dry 24/7. Got this in November and now it’s April, amp clamp will not turn on so I took it apart and found heavy corrosion on the circuit board.

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.