CrocSee AC 80-260V 100A CRS-022B LCD Display Digital Current Voltage Power Energy Frequency Power Factor Multimeter Ammeter Voltmeter with 100A Split Core Current Transformer

This is an excellent product that I continue to be very happy with. I wanted to mention a few things that might be useful to potential buyers.1. Expanding on the instructions of how to reset the total energy to zeroThe instructions say to hold the button down for 5 seconds until the energy value flashes and then release the button and tap it once again. That's the correct procedure, but what might be confusing is that there's an intermediate event that's not mentioned.When you press and hold the button, after 3 seconds the main display disappears and the words SET CLr appear. Since the energy numbers didn't start blinking but instead the screen with the energy numbers just disappeared from view you might be tempted to release the button. But don't do that! Instead keep holding the button for another couple of seconds and the main screen will reappear with the energy numbers flashing. ONLY THEN can you release the button and tap it once more to zero the energy value.2. Understanding the precision of the energy numbersNote: In what follows I'm using the term "precision" to indicate the precision of what can be displayed, not reproducibility of repeated measurements.Because the energy display has only one fixed position for the decimal point - to the right of the leftmost digit - there are some limitations on the precision that can be displayed in different energy ranges, particularly above 10 kWh. I've attached some photos to illustrate this.The device has an energy resolution of 1 watt-hour (Wh). It won't display, for example, 0.5 Wh. A photo shows a display of 002 Wh.Many people will want to look at energy use above 100 Wh, and at that point the device begins displaying three significant digits. A photo shows a display of 132 Wh and another at 896 Wh. The measurement uncertainty in this range is 1 Wh. For example in the 132-Wh photo we know the energy is at least 132 Wh but less than 133 Wh. At 100 Wh this would represent a 1% uncertainty and it would be a 0.1% uncertainty at 999 Wh, just before the display mode changes.Above 999 Wh the decimal point appears and the display units change to kilowatt-hours (kWh). There are still three significant digits because the energy is displayed with two decimal places. Photos show 1.23 and 9.52 kWh. Just as in the previous display mode, the uncertainty beyond the last digit represents 1% at 1.00 kWh and 0.1% at 9.99 kWh.But at 10 kWh the fixed-position decimal point comes into play and things change. Because there is no position for a decimal point between the second and third digits the display can't show 10.0 but instead has to show 010, which is shown in a photo. This means that we know the energy is at least 10 kWh and less than 11 kWh. This 1 kWh uncertainty represents 10% at 10 kWh - far higher than the precision associated with measurements up to now. Obviously this 1 kWh uncertainty will become less important at higher energy ranges, representing 1% at 100 kWh and 0.1% at 999 kWh, the maximum energy that can be displayed. But it may be to much for some users wanting precise energy measurements closer to 10 kWh.To summarize, in the energy range from 100 watt-hours to 10 kilowatt-hours the device can display energy with a precision no worse than 1% and as good as 0.1%, which may be perfectly adequate for most users. Users who want to make careful measurements in the 10-30-kWh range - which may include PHEV owners and those partially recharging EV's - need to be sure that they understand what the display is capable of in this range.3. Exceptional customer-service experienceI bought two of these units in April, 2022. After making the measurements I needed I put them aside. In January 2025 I need to make some further measurements but had problems reliably resetting the energy to zero (which later turned out to be my own misunderstanding. See item 1.) I contacted CrocSee's customer service, hoping that they could tell me what I was doing wrong. Instead they offered to replace the units even though they had been out of their one-year warranty for almost two years! I very much appreciated this exceptional customer service, and I'm very happy with the product, which is meeting all my requirements.

Excellent produit

Warning on installation: This meter is not safe when its voltage terminals are connected directly to AC terminals or circuit breaker. It is not UL-listed or NEC compliant! There is no short circuit protection if board fails or arcs, and may catch fire if no additional low-current (125-250mA 250V+) fuses are installed externally, because the main circuit breaker will not activate before the boards and thin connecting wires burn.Note: connection schematics is not perfect on Amazon page: the L (live) and N (neutral) are swapped. Terminals 2 and 3 are actually connected together inside, and with shown schematic the current transformer is at L voltage, it is better to keep it at N potential.This is a digital meter based on V9811A power meter chip (those interested can see datasheet). It measures true active power, and averages voltage and current. It has an option of electronic calibration, but probably the manufacturer does not do it so the accuracy of readings are within 2-3%. It is a perfect device for monitoring power consumption of an air conditioner, dryer or electric range - any load that uses two wire connection to 120V or 240V AC power. It has one input for the current transformer.Sometimes it is desirable to monitor the split-power (a typical US residential wiring), and that is also possible when you run both live wires through the current transformer in opposite directions to sum currents in phase A and phase B, and connect voltage inputs between neutral and one of the phases.The other option is to order two current transformers and connect them in parallel. The total 100A may not be sufficient for whole home monitoring (max power is 12kW).Operating on split-phase also creates a bit of a problem in interpreting results: for 120V appliances the current reading will be correct, while for 240V appliances the current will show up as twice the actual current, but the power will show up correctly. This is a typical problem of a split-phase measurement. It would be nice if there was a meter with two current transformers which could display separately currents on each phase and compute total power based on sum of the currents. That is why it gets 4 stars only.

I was curious to monitor power usage of my traditional electric water heater. This device allowed me to do that. A 10 minute shower takes about 2 kilowatts (23.9 cents) of power. A fast 5 minute shower used 900 watts or about 11 cents. My dishwasher used 1.17 kilowatts or (14 cents) (of power to heat the hot water that went into it.) Two adults use about 62 cents a day or $18 a month in power. I discovered the hot water heater actually drew about 5% more power than it was rated for. (This is mostly because the voltage delivered by the power company was 250 volts instead of a 240; but this is within acceptable limits.) The water heater also fully "recovered" within about 5-7 minutes of the shower being done. Being able to monitor usage and know what usage is costing is one of the first steps toward conservation. This device keeps tracks of usage during power outages better than the plug in kill-a-watt plug in electric monitors that reset to zero when power is lost. Those are easier for smaller load items. All the numbers can also be checked and compared to both an amp meter, and your electric meter as well. It is much easier to use this device than turning off all the other items in your home via circuit breakers and then counting the little dots that represent one watt of power moving across the bottom of your digital electric meter with a stop watch. Many devices also turn on and off and use a range of power over a variety of time. This makes it easy to track cumulative usage of changing loads.