2 Pieces AC Current Voltage Amperage Power Energy Panel Meter LCD Digital Display Ammeter Voltmeter Multimeter with Split Core Current Transformer CT AC 80-260V 100A Multi-Function Power Monitor

The media could not be loaded. The current most helpful review says "Made in USA" when clearly these meters are not, these meters are made in China. Also, they do not HAVE to run off of 120Vac, they will run off 80-260V. With those corrections out of the way, these meters work well.This meter helped me identify a serious problem with a 5-ton Trane heatpump unit. And no, it's not hard to stop a Trane, all you need is a faulty low pressure sensor switch and it will not only stop but also start running backwards in mere milliseconds.Be advised these meters alarm on Power only. I knew what they did when I bought them, I only wish they had a version that could be set to alarm on voltage or current or all three via independent settings. It would be nice if there was an audible alarm of some sort. I also wish they had a mounting box or panel with an appropriate cutout. (product improvement suggestions) Line voltage varies and so therefore current draw will also vary and therefore Power varies (voltage times current).In my scenario I have a 5-ton Trane heatpump unit whose compressor liked to run backwards. If your heatpump sounds louder than normal or hits like a sledge hammer while running, it's running backwards.Contrary to popular belief, running backwards did not harm the motor nor the scroll compressor that the motor drives (this unit is 11 years old). However, it does eat a lot of energy for no gain. This needleslly increases the electric bill considerably. It is also interesting that when running backwards, the compressor (I put the meter in the heatpump on the leads running into the compressor) draws more current and therefore has more power consumption. When running correctly, this compressor draws 16.6 Amps at 234.9V as measured. When running backwards it draws 21.9 Amps at 235.7V as measured. That is a 32.5% increase in current and therefore power for no gain (ie no heating or cooling inside the house = total wasted energy). Once I knew that, then I needed a permanent means with alarm and real time display inside the house. That's where these meters saved the day.It is also interesting to note that the impulse from forward to reverse draws a very short (milliseconds) 100 Amp spike. I was curious, so I recorded this with a data logger that I also got here from Amazon, namely the Supco LCV LOGiT Current and Voltage Data Logger (1s minimum data interval was sufficient to catch it twice out of 4 times), and I saw it instantly on an oscilloscope also bought here on Amazon, namely the Owon SSO8192.These power meters are great to give a real time, portable and inexpensive current, voltage and power reading but are not usefull for capturing fast spikes like the more expensive equipment.What was causing this reversal was a defective low pressure switch on the unit. This switch would let the 24V contactor coil voltage drop intermittantly, and for less than a millisecond. The resulting sound has a BANG loud enough to shake the 4,000 sqft house (through the vent system) followed immediately by a louder running compressor as it starts running backwards (like it was digging deeper). From forward to reverse in milliseconds with a 100A spike. BANG! By shorting the leads running to the low pressure switch, the unit now runs as normal, no idea what this has done to longevity. My theory as to why this Trane 5-ton scroll heatpump compressor draws more amps in reverse, is because the compressor must have an internal anti-backflow valve or device of some kind.With this meter I was able to temporarily monitor directly inside the outdoor unit and I can now permanently monitor the current draw from inside the house by connecting this meter to the breaker box lines running to the heatpump outside. I also have the alarm set to 5.3kW (240V times 22 Amps). The fans draw 4.7 Amps. 16.6+4.7=21.3A running correctly. In reverse that would be 22+4.7=26.7A. This way, I will have an exact alert if the heatpump ever tries to reverse again. No need for hearing accuity of the compressor. Note I wired this inside the breaker box, directly across the breaker feeding the heatpump unit with the current sense transformer on one of the wires.The permanent fix for the heatpump was to replace the low pressure switch (simply put a new one in line and abandoned the old). We also replaced the contactor as the contacts were severly damaged. I had the start capacitor and hard start unit replaced for piece of mind.I will leave this meter in place as I do not know if this same failure or another such as the high pressure switch will fail again in the future. I appreciate the peace of mind this meter with flashing screen alarm provides.Note, you can turn the LCD off by pressing the button and yes, on alarm it will still flash. It holds the LCD backlight setting (on or off) through a power outage AS WELL AS the power alarm setting. 2 minutes tested. It may hold these settings longer, I don't know. But for my purposes, that is more than long enough for the guardian 22kw to kick on and the transfer switch to automatically kick in during a power outage. For my purposes I don't care, but I also noted it did hold the kWh accumulation for two minutes as well.The leads on the CT transformers are relatively short (about 4-6 inches), I soldered on an additional 2 ft of tined multistrand 20 AWG silicone insulated (600V) wire to them. Solder station (Andolar 60W), solder (60/40 rosin core) and wire (Haerkn) were also bought right here on Amazon. I used electrical tape (3M Super 88) bought right here on Amazon to insulate the joints, you can use heat shrink tubing for a more professional look.At $15.30 apiece if you buy two, this is a very inexpensive troublshooting and monitoring tool.I hope this helps someone.

A few facts:* I am only talking about the "AC 100A Meter(Split Core Transformer)" style; the other 3 styles you can order from this page look dramatically different and no doubt have extremely different functionality, so don't rely on customer reviews or answers that do not specify which style they bought; also, it is probably a good idea to specify the style you are considering purchasing if you are asking a question on here. (Or not, you decide.)* You will have to supply your own leads to connect directly to the power source. The wires and alligator clips you see in the pictures are my own.* CONCLUSION: Don't. Assume. Anything. Ever.A few opinions:* NEGATIVE: This meter does not keep track of the amount of time that has passed since the watt-hours were reset, so you will have to mark down the time somehow if you intend to calculate daily/monthly energy costs.* POSITIVE: This meter survives power outages without losing track of watt-hours used, which every power meter should do and is a huge benefit in areas like mine where the power goes out frequently and I cannot monitor the power daily.* CONCLUSION: Just buy a couple of these and you'll be happy you did.* NOTE: I live in very rural Florida, USA--notice the electobraid in the pictures which implies that I have horses grazing in my front yard--so code violations and permits are basically non-existant. So, please don't leave comments regarding code violations from my pictures or assume that I was the person who made them. Also, please don't flame me because you assume to know my political persuasion: My family is divided politically and religiously (it would blow your mind if I explained it all), and we still get along super-well because we all love and respect one another, thank you very much. This posting is about electrons, not people.220-volt measurements:* I saw conflicting answers regarding the measurement of 220-volt (or 240-volt... whatever, I get it) in places like the United States where there is a neutral wire that divides the voltage in half. My use case is a main panel that supplies power to a sub-panel in my workshop where some circuits are 110-volt and some are 220-volt. (NOTE: The voltage between the red and black wires is 220 volts, and the white wire is the neutral that is halfway in between. Thus, red to white is 110 volts and black to white is 110 volts, albeit at opposite phases but what the heck the appliances are stupid and don't really care about phases.)* I have 3 of these devices, so I am able to show my results in real time. Ignore the watt-hour numbers in my photos, because the meters were reset at different times. Pay attention only to the volts, amps, and watts. (I'll look it up later so I become a supposed expert, but right now I really do not understand what power factor even means. I am pretty smart and was literally at the top of my class in my 300-level college electronics course, so I know what I know and I know that I don't know everything.)* Everybody who answered the question about measuring 220 in this situation (at the time I read it) agreed that you should put the power leads on both ends (red and black) of the 220 circuit, so in all 3 samples the power leads stay in the same place.* Of course, if you have an appliance (like my air conditioner or my well pump) that only uses 220 and doesn't use the neutral line at all, you could simply span the red and black wires and ignore the white wire. But for subpanels where there is a mix of these appliances and circuits, this is not so simple.* Results when the coil was on the black side (and the #3 power leads were spanning the red and black):* #1 black-side meter (left): 120 V, 5.2 A, 585 W* #2 red-side meter (right): 122 V, 0.3 A, 22.5 W* #3 red/black meter (middle): 242 V, 0.3 A, 46.1 W* #1 PLUS #2 = 607.5 W, not 46.1 W!!!* Results when the coil was on the red side (and the #3 meter power leads were spanning the red and black):* #1 black-side meter (left): 120 V, 5.5 A, 615 W* #2 red-side meter (right): 122 V, 0.3 A, 22.5 W\* #3 red/black meter (middle): 242 V, 5.6 A, 1.25 kW* #1 plus #2 = 637.5 W, not 1.25 kW!!! (OMG, Becky!)* Results when the coil was on the white side (and the #3 meter power leads were spanning the red and black)... what the heck, this sort of answers the question of whether current flows on the neutral or not (SPOILER ALERT, it does, why else would it be made of copper):* #1 black-side meter (left): 121 V, 5.3 A, 593(5?, thanks Siri!!!) W* #2 red-side meter (right): 122 V, 0.3 A, 22.6 W* #3 red/black meter (middle): 243 V, 5.1 A, 1.16 kW* #1 plus #2 = 617.6 W, not 1.16 kW!!!* CONCLUSION: It is unpossible to accurately measure a split voltage system with a single meter. If you put the coil on one end (black) or the other (red) you will get the correct amperage for that side but it will inaccurately multiply that by the total voltage and overstate the watts. If you put the coil in the middle, you will get the larger of the two amperages from either side multiplied by the total voltage and (IMO) overstate the watts (maybe?).* QUESTION: My dad always told me you "pay" for the other side even if you're not using it, so you should balance out the 110-volt circuits as much as you can to maximize your cost. Is that true?* OBVIOUS CONCLUSION: I have gone to all the trouble of buying 3 units and giving you all of the facts (backed by photos), so you should not give me a thumbs down even if you completely disagree with anything I have said. You should give me a huge thumbs-up and politely state your disagreements with me to make yourself feel better, look smart to everyone else, and actually educate me in the process.Thanks, and G-d bless.