Withstand Voltage Tester

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The non-contact voltage tester is the quickest and easiest way to safely check the current in wires, sockets, switches, or old lamps that have mysteriously stopped working. This is a useful tool that every electrician carries with him. After talking with a senior electrician with 20 years of experience and using seven leading models for eight months of testing, we found that Klein NCVT-3 is the best choice.
Klein can detect standard voltage and low voltage, and is equipped with a handy flashlight-when the light is off, you may need a good tool.
Klein NCVT-3 is a dual-voltage model, so it records both standard voltage (indoor wiring) and low voltage (such as irrigation, doorbell, thermostat). Unlike some models we tested, it can automatically distinguish the difference between the two. This feature also makes it compatible with the tamper-proof sockets now required by electronic specifications. The controls on the NCVT-3 are intuitive and display clear. When tested in a circuit breaker panel full of live and dead wires, it is sensitive enough to read dead wires from a short distance without falsely reporting live wires from nearby . But the most useful feature is actually its bright LED flashlight, which can be operated independently of the voltage tester. For tools that are often used in dim basements or when the lights are not working, this is a secondary but very useful feature, and Klein is the only model we tested with this feature. According to the company, the tool can also handle drops of up to 6.5 feet, which is not bad considering it is a sophisticated electronic product.
This dual voltage tester is similar to our choice in the most important respects, but some of its small details are more annoying.
If you can’t find Klein, we also like the Milwaukee 2203-20 voltage detector with LED. Its cost is about the same, and similar to Klein-testing standards and low voltage, and ease of use. But the flashlight is not so bright and cannot be used alone without the tester. It also emits a very loud beep and there is no mute option.
Klein can detect standard voltage and low voltage, and is equipped with a handy flashlight-when the light is off, you may need a good tool.
This dual voltage tester is similar to our choice in the most important respects, but some of its small details are more annoying.
I have been writing and reviewing tools since 2007, and articles have been published in Fine Homebuilding, This Old House, Popular Science, Popular Mechanics and Tools of the Trade. I also worked as a carpenter, foreman and site supervisor for 10 years, working on multi-million dollar residential projects. In 2011, I also demolished my 100-year-old farmhouse, which required a brand new electrical system.
For more information about non-contact voltage testers, I talked to the people who use them every day: Mark Tierney of Tierney Electrical, Hopkinton, Massachusetts. Tierney has 20 years of experience and has been running his own company since 2010.
The non-contact voltage tester only needs to be close to detect the current in the wire or socket. 1 It is the size and shape of a fat sharp. The detection takes place at the probe tip. In many cases, the probe tip is designed to be pushed to an outlet. Since electric shocks are unpleasant at best and extremely harmful at worst, this tool is useful for even the lightest electrical tasks, such as troubleshooting a thermostat or installing a dimmer switch.
Obviously, it is a great tool for DIY electricians, but even people with zero electrical inclination can benefit from having one. I usually use it as the first stage of troubleshooting before calling a professional electrician.
The non-contact tester can also help map your existing electrical system. I have not lived in any house close to the correct labelled panel. If you have an old house or apartment, your electrical panel is probably also mislabeled. Solving this problem is a time-consuming process, but it is possible. Turn off all circuit breakers except one, and then check for activity around the house. Once you figure it out, label the circuit breaker and move on to the next one.
Most non-contact testers only record standard voltages. After reading about the subject, we decided that the dual-range voltage tester is more suitable for home toolboxes. For standard voltage, it can still work normally, and there is the additional benefit of low voltage detection, which is useful for doorbells, thermostats, some AV equipment, irrigation and some landscape lighting. The prices of dual-voltage and single-voltage models are mainly between US$15 and US$25, so dual-range devices make sense as a one-stop tool for non-professionals; having the capability and not using it is more important than needing it and not owning it. good.
When deciding which models to test, we studied Amazon, Home Depot, and Lowes products. We have also targeted reputable power tool manufacturers. Since then, we have reduced the list to seven.
We conducted some tests to determine the overall practicality and sensitivity of each tester. First, I turned off a circuit breaker on the electrical box and tried to find out which of the 35 wires coming out of it was broken. After that, I took a dead wire to see if I could bring the tool close to the live wire and still get the tester to read negative. In addition to these structural tests, I also used the tester to connect some sockets and installed some dimmer switches, cooktops, ceiling fans and some chandeliers.
Klein can detect standard voltage and low voltage, and is equipped with a handy flashlight-when the light is off, you may need a good tool.
After researching topics, talking with electricians, and spending hours testing seven leading models, we recommend Klein NCVT-3. NCVT-3 has a very intuitive indicator light, a beautiful on/off button and an onboard LED that works like a small flashlight. This is a great feature, because when you check the wire voltage, the light may not work properly. It is also compatible with the tamper-proof socket required by the current code. NCVT-3 has a battery life indicator and a durable body that protects its sensitive electronic equipment from drops of up to 6½ feet.
Most importantly, NCVT-3 is very easy to use. It is a dual range device, so it can detect standard voltages (sockets, conventional wiring) as well as low voltages (doorbell, thermostat, irrigation wiring). Most testers only detect standard voltages. Unlike most other dual-range models, it can automatically switch between ranges without using a cumbersome sensitivity dial. The LED bar graph on the side of the tool indicates the voltage you are dealing with. The low voltage detection lights up the two orange lights at the bottom, and the standard voltage lights up one or more of the three red lights at the top. Many companies sell separate high and low pressure detectors, but for non-professionals, it makes sense to put them in one tool, especially if it is as easy to work as Klein.
In my own basement, wires are nailed to the ceiling above the fluorescent lights, so even if the lights are on, it is difficult to handle the wires. Of the two models with flashlights, NCVT-3 is the only one that can be operated independently of the test function, which is really good.
LED flashlight is a highlight of NCVT-3. In my own basement, wires are nailed to the ceiling above the fluorescent lights, so even if the lights are on, it is difficult to handle the wires. Of the two models with flashlights, NCVT-3 is the only one that can be operated independently of the test function, which is really good. When the tester is activated, there will be a series of beeps and flashing lights. If you just want to use a flashlight, it is good to be able to avoid it. Our runner-up choice, the Milwaukee 2203-20 voltage detector with LED also has a flashlight function, but it will only light up when the tester is turned on, so anyway, you have to listen to the beeping, there is no way even if you are in a well-lit room Turn off the flashlight when working in the city. The NCVT-3 LED is also brighter than Milwaukee.
NCVT-3 also has a very durable feel. According to the manufacturer, it can withstand a 6.5-foot drop, so if you experience a fall, this model will provide you with a chance to survive. In addition, the keys are sealed, and the lid of the battery compartment is sealed, so the NCVT-3 can withstand a little rain and humidity. Klein has a video about the tool, and it looks like it’s under a dripping tap.
When we asked the electrician Mark Tierney if he would recommend any manufacturer to the homeowner, he told us “the most reliable one is Klein.” He also likes models with LEDs. He said that for homeowners, “they will get two great features in one tool.”
Regarding battery life, Klein said that two AAA batteries will provide 15 hours of continuous tester use and 6 hours of continuous flashlight use. This is sufficient for occasional users, as we said, it is nice to have a battery indicator so you will know when it goes low.
We are not the only ones who like NCVT-3. Clint DeBoer, who wrote on ProToolReviews, stated that the tool “Even if you do electrical work occasionally, you can almost easily get it.” He concluded: “This is a well-designed tool that can do what it should and do. Very good. Pick one. You won’t regret it.”
NCVT-3 has also received generally positive reviews on Amazon and Home Depot. Most of the negative news on Amazon comes from people who like the tool but are disappointed that it cannot be plugged into the socket. As mentioned above, this is not a problem because it can still detect the current and only show it as a low voltage (and make it compatible with the tamper-proof socket required by the code). To really confirm the standard voltage on the socket, it is easy to unscrew the cover and place the tip of the tool on the side of the socket where the wires are located.
NCVT-3 is unique because it cannot be plugged into a socket. At first glance, this seems to be a problem, as most other non-contact testers can read power from the socket just by inserting it into an opening. The reality is that because it can read low voltages, NCVT-3 can still draw current from outside the socket, which is crucial when dealing with tamper-proof sockets that are now required by electrical codes. To insert the plug into one of the sockets, equal pressure needs to be applied to the two pin openings (this is a safety issue for children). With these sockets, the traditional non-contact voltage tester does not always work because it can only read standard voltages. As Bruce Kuhn, product director of product development, test and measurement at Klein, told us, “If you make such a tester sensitive enough to detect the voltage on the’outside’ of a tamper-proof socket, then it is in a crowded electrical box. A hot wire.” 2 Because NCVT-3 is designed to detect standard voltage and low voltage, when it is placed in the opening of a live tamper-proof socket, it will pick up the standard voltage, but from a distance, it appears to be low Voltage, still confirm that the socket is live.
There are control buttons on the side of NCVT-3, which Tierney told us to pay attention to. He warned that models with side buttons are easy to open when placed in a pocket, which is not only annoying, but also accelerates battery consumption. One difference from NCVT-3 is that the buttons are flush with the surface; most buttons like this protrude from the side of the tool and can easily be accidentally activated. I used the NCVT-3 in my pocket for a day, and it never opened.
This dual voltage tester is similar to our choice in the most important respects, but some of its small details are more annoying.
If Klein is not available, we recommend the Milwaukee 2203-20 voltage detector with LED. It has many of the same functions as Klein NCVT-3, but the flashlight is not as bright and cannot be used independently of the tester. It also emits an incredibly loud beep (no mute option). This may be beneficial in a noisy work site, but after I spent 45 minutes checking the wires in the basement, the volume was enough to make me a little crazy.
Nevertheless, Milwaukee can detect low voltage and standard voltage, and there is no manual switch between them, so it is as easy to use as NCVT-3.
In 2019, we noticed that Klein now owns NCVT-4IR. It looks the same as our choice, but also includes an infrared thermometer function. We believe that this is not worth the increased cost for regular household use.
We also noticed models from companies such as Meterk, ToHayie, Taiss, and SOCLL. These are common tools from lesser-known companies. We feel that it is safer to recommend testers from verified electrical diagnostic equipment manufacturers.
We tested Klein NCVT-2, which is very similar to NCVT-3. It is also a dual-range model that can automatically detect between the two ranges, but it does not have an LED; the on/off button is proud of it (so it is likely to be opened in the pocket); and the case does not have that durable feel.
We have also seen Greenlee GT-16 and Sperry VD6505 use the dial to select the sensitivity between low voltage and standard voltage. During our testing, we found that when there are multiple wires in the area, these models will receive signals from other wires, which makes it difficult for us to know when the sensitivity is reduced enough to detect only the wires we want. It’s hard to master the tricks of sensitivity dials, and prefer the simpler interface of Milwaukee and Kleins.
Greenlee TR-12A has a two-pin design specifically for tamper-proof sockets, but it can only read standard voltages instead of low voltages, so we think NCVT-3 is more useful.
Klein NCVT-1 only detects standard voltage. I have owned one for many years and have always found it to be accurate and reliable, but it makes sense to obtain a model that can also detect low voltages.
We asked Klein to accurately explain the working principle of the non-contact voltage tester. The company told us: “The non-contact voltage sensing device works by inducing the electromagnetic field induced around a conductor powered by an alternating current source (AC). Generally speaking, The higher the voltage applied to the conductor, the stronger the field strength of the corresponding induced electromagnetic field. The sensor in the non-contact test equipment responds according to the field strength of the induced electromagnetic field. Based on this principle, when the non-contact voltage tester is close to the energized conductor When placed, the induced electromagnetic field strength enables the device to “know” whether it is in a low-voltage field or a high-voltage field.”
I took the Klein NCVT-1 around my own home. It only detects standard voltages. The success rate of detecting power from tamper-proof sockets is about 75%.
Doug Mahoney is a senior staff writer at Wirecutter, covering home improvement. He has worked in the field of high-end construction for 10 years as a carpenter, foreman and supervisor. He lives in a 250-year-old farmhouse, and he spent four years cleaning and rebuilding his previous home. He also raises sheep, raises a cow, and milks him every morning.
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Voltage withstand testing is done with a high voltage source and voltage and current meters. A single instrument called a “pressure test set” or “hipot tester” is often used to perform this test. It applies the necessary voltages to a device and monitors leakage current. The current can trip a fault indicator. The tester has output overload protection. The test voltage may be either direct current or alternating current at power frequency or other frequency, like resonant frequency (30 to 300 Hz determined by load) or VLF (0.01 Hz to 0.1 Hz), when convenient. The maximum voltage is given in the test standard for the particular product. The application rate may also be adjusted to manage leakage currents resulting from inherent capacitive effects of the test object. The duration of the test is dependent on the test requirements of the asset owner but is normally up to 5 minutes. The applied voltage, rate of application and test duration depend on the specification requirements of the equipment. Different test standards apply for consumer electronics, military electrical devices, high voltage cables, switchgear and other apparatus.[2]

Typical hipot equipment leakage current trip limit settings range between 0.1 and 20 mA[3] and are set by the user according to test object characteristics and rate of voltage application. The objective is to choose a current setting that will not cause the tester to falsely trip during voltage application, while at the same time, selecting a value that minimizes possible damage to the device under test should an inadvertent discharge or breakdown occur.