In my opinion, Fluke makes the best electrical test equipment available. Unfortunately, their price is much higher than anything else comparable on the market, and they don't make anything that's anywhere close to as all-encompassing as the EX623. As a stationery engineer, there are many different types of systems that I maintain and test, including electrical and refrigeration. Before the EX623, I used to keep two multimeters with me along with an IR thermometer and a digital thermometer. As you can imagine, I was pretty excited about the 623. I've owned the Extech EX623 for a few months now, and have come to use every one of its functions, though some of which much more than others. Some seem to be impressively accurate, while others are less so, and take several seconds to settle to zero. The AC clamp seems pretty accurate, though I do get a reading of .18 when first turning it on, taking up to ten seconds to settle into .03A, which is more just annoying than actually a problem. The peak current setting is nice and works well for telling the LRA of motors. The DC clamp has a digital zero which is a nice upgrade from meters with a manual dial that I have used in the past. The microAmp feature is nice and seems very accurate, although admittedly this is not a function that I use often myself. Probably the most used feature is also the one I'm least pleased with: the Ohmmeter. There are various ranges for resistance that can be selected, but I typically leave it on auto-range. As a result, most things I check will show up hundredths of Ohms, and for some reason the meter will never settle on anything in that range. It will also take several seconds to read resistance of anything accurately, typically starting out with a higher than actual reading then eventually finding and settling on the correct resistance. I've not owned something that does anything like this, and while it does not affect testing 98% of the time, it is annoying. The EX623 also has a diode test setting, and a continuity setting which emits a beeping when resistance is below 50 Ohms. The voltmeter is also something that has occasionally been a bit of a nuisance for me, more due to personal error than anything else. Like the ohmmeter, when first selected the 623 defaults to auto-ranging. Likely as an effect of just picking up electrical noise, the meter will display a reading of 10-20mV, though when near a power source up to 500mV with nothing connected. This has sometimes led me to believe that a unit is powered even though it is not, especially 208 Volt systems where irony has it the meter will often display 212mV, forcing me to pay extra attention. I've been trying to get in the habit of selecting a higher range to avoid this. My other complaint would be that the EX623 seems to take a bit longer to give a reading, first giving an "OL" then the measurement a second later. My other meters seem to be a bit less delayed. Otherwise the voltmeter is perfect. The capacitance check seems very accurate as well, and has an unusually high range of 40,000mF. I have never needed to test a capacitor that big, but it is a nice feature nonetheless. The duty cycle/frequency feature is something that I can't comment that well on because I only really work with power from a 60Hz source and have not worked with any variable speed motor drives. Even generators have given a steady 59-60Hz reading. What is cool is that the ExTech will also display frequency in smaller text at the bottom of the readout screen in any the the settings other than resistance and temperature. The non-contact voltage detector also works in any setting except temperature and has all but eliminated the need for my standalone NCVD. Like most built-in multimeter NCVs, I've found it to be extremely sensitive, picking up voltages from receptacles and through heavily insulated NM cables, but also picking up voltages several inches away from TVs and fluorescent lights. The IR thermometer with laser pointer is also truly a unique feature on a multimeter and has been much more handy than expected, being used to check surface temperatures of motors and other devices where I would not have normally brought a separate thermometer. The dual K inputs are great for refrigeration work, and the included probes are of decent quality though I plan on eventually replacing them with a heavier one and clamp on types for refrigerant and water lines. There is also a shutter to allow only the test leads or probes to be connected at a time to prevent the probes from being accidentally backfed from a voltage source connected to by the leads. Some other features that are nice are the backlight, though I do not like how it is activated (you need to hold the HOLD button for several seconds and then the light will automatically shut off after a period of time). Like most multimeters the EX623 will shut off to save battery after 30 minutes of inactivity, but this can be disabled which has been great for trying to find startup currents for units that are only intermittently on and difficult to force a startup. I do not like the obnoxious beeping noise emitted when selecting inputs and unfortunately it cannot be disabled. The included carrying bag is also a nice though but it is definitely not a high quality item, being made of thin, scratchy nylon fabric. It has still saved my multimeter and probes from being lost and knocked around in my toolbag and the shoulder strap or belt loop might be good for someone that would carry it around constantly. Overall I am pretty happy with the ExTech EX623 and would definitely recommend it to anyone that troubleshoots and repairs a wide range of equipment. It is a little slower than I am used to and also a bit more sensitive with its readings, but so far has proven to be accurate and dependable. It has replaced many older standalone pieces of test equipment that I used to keep with me daily, including another non-clamp multimeter and a IR thermometer. I would be more satisfied if the measurements were a bit faster and if (even though it's not typical of a clamp meter) there were a built in stand so I didn't have to find something to clamp on to or rest against to see the display. It would have also been nice to have an option to test current in line in the 10 Amp range. Otherwise, The ExTech EX623 is definitely a great tool at an even better price. About the only thing I wouldn't use it for is working strictly in electronics, where I prefer to use a different multimeter with a few different functions and features.
