Provided to KeepOnTesting for independent review, we have the $16 MSRP AC voltage detector device from Tesmen.
This device is easy to carry, resists dirt and water, never requires metal contact to operate, and uses conveniently provided 1.5V AAA cells. The tailcap battery access opens without tools, and is very roomy inside.
Unit turns on with a long-press of the power button, and off with a short press of the same button. A beep and red flash at the tip confirms your choice. After 5 minutes non-use, it will automatically power off. If your battery voltage becomes low, an indication shows up in the screen.
Below is an image of the brief power-up screen with all the digits displayed.
After turning on, you have two sensitivity levels to choose from. The default sensitivity 12V-1kV is good for lower voltage or greater distances from the conductor. You want to use this first. If you want less sensitivity for better discrimination, you choose the 70V-1kV range with a quick press of the "S" button, and again to cycle back to high sensitivity. In either mode, response is nearly immediate. Very easy to maneuver the device back and forth and get real-time feedback. At the end of this review, I have some actual images of testing a US socket with both sensitivity levels.
The display is usually backlit in green, until voltage is sensed, in which case display turns to red. A level meter and two-digit percent will clearly inform you the level of induction. In addition there is a clear yet moderate volume beep that accompanies these readings. As the % goes higher, the beep intervals get shorter, until an ultimate frenzied crescendo. Well done! Some users might prefer louder beeping, but that would require a less water resistant case most likely.
In addition to the constant red backlight on the screen when HV is detected, there is also a separate red light on the front of the unit where your tip is aimed. This flashes at increasing rates in concert with the audible beeps. So even if the screen is tilted not visible, there remains plenty of indication that high voltage is present.
Working in the dark, or need a flashlight? A long press of the S button turns on the large cool white spot LED on the front. It appears to be a standard 8 mm, slightly recessed, and surrounded inside by a rubber O-ring. It stays on until you turn it off.
The green body color of the test unit it an excellent choice. The box shows red and blue are also color options. The quality of the plastic is excellent, with lightly textured surface, however no rubber grip. When your thumb finds something rubbery, it's the selector buttons. A integrated pocket clip works for shirt or pocket. This gray clip is retained by the tailcap o-ring, which serves as water barrier for the battery bay.
I feel absolutely safe using this unit. There is no exposed metal at the tip or anywhere else on the device. It's entirely a non-contact voltage device. That doesn't present any limitation here, because the default sensitivity is outstanding. The tester claims a rating IP66, providing both waterproof and dustproof capabilities. Also carries CAT Ⅲ 1000V, CAT Ⅳ 600V rating. Operates for 50 or 60 Hz AC voltage.
The probe tip is oriented properly for the vertical install direction of US plugs. Meaning, when applying the tip in most US households, the display is conveniently facing you. The rectangular tip is narrow enough to be pushed into the socket, but sometimes I found this is not necessary for a good reading. There is a metal blade inside, but it remains protected by solid plastic.
The owner's manual is one huge double-sided sheet folded into 12 panels. Languages include English, German, French, Italian, Spanish, Japanese. It states you have a 3-year warranty and lifetime technical support. The device should be used between 0 and 40C, and below 2000m altitude.
There are no screws to open the body of the device, it seems to be ultrasonically sealed together. Feels super rigid, and the seams are not obvious at all. Unfortunately this means no tear-down today, sorry!
The size of the device is 1.61 x 1.02 x 6.22 inches and weights 2.82 Ounces
Additional information from the manufacturer web site:
In summary, this has quickly become my go-to device for NCV measurements. Nothing else I have comes close to the response and sensitivity and feedback. It's super handy, easy to operate, and perfectly safe in my opinion. The green color makes it unique and the rectangular shape and pocket clip means it won't roll away from you. It's definitely a keeper, and if I didn't have one I would buy one right away. Definitely a five-star product from a company who makes plenty of interesting devices. I recommend reviewing their products at your earliest opportunity.
Below are actual usage images. Notice that the default high sensitivity range falsely reported ground as hot, but switching to the lower sensitivity provided more conclusive feedback. This wasn't always the case, it's nice to have the two levels of sensitivity.
I'm using 120V 60 Hz sockets. The LCD polarizing angle is just right for the viewing angle. Sorry if I didn't always get it right for the pictures near the end of this review.
High Sensitivity Neutral 0%:
High Sensitivity Hot 76%:
High Sensitivity Ground: 9% (cannot insert tip this time)
Low Sensitivity Neutral 0%:
Low Sensitivity Hot 35%:
Low Sensitivity Ground 0%:
Are there any downsides? Not really. The unit doesn't operate on 1.2V NiMH rechargeable cells, so you may want to remove those "primary" chemistry cells before they leak on you. Easy enough to do.
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