Search
Non-Contact Voltage Detectors: How They Work, Comparison, Top Pick
Share:
Santronics Ultimate AC Voltage Detector
Santronics Ultimate AC Non-contact Voltage Detector.

Non-Contact Voltage Detectors: How They Work, Comparison, Top Pick

With any electrical project; replacing a: wall switch, receptacle, light fixture, doorbell or thermostat, you’ll need essential electrical tools, which includes a safe method of detecting the presence of AC electricity.

Easy to Use: Place the tip of a non-contact voltage tester near a circuit or wire where AC voltage is present (ref. featured image). If voltage is detected, the tip will illuminate or change colors from it’s standby mode – and an audible alert may sound (varies per detector).

The Science of a Non-Contact Voltage Detector: Fluke provides an in-depth explanation on how these detectors work.

Compare †Voltage RangeDual RangeCAT III RatingCAT IV RatingBattery TypeAudible AlertWork LightPower SwitchIR ThermometerProduct Page ‡Purchase §
Extech DV4050 – 1000VAC1000VN/R3 x LR44
Visit ExtechBuy now from Amazon
Extech 40130100 – 600VAC600VN/R2 x AAA
Visit ExtechBuy now from Amazon
Extech DV20100 – 600VAC600VN/R2 x AAA
Visit ExtechBuy now from Amazon
Extech DV2450 – 1000VACN/R1000V2 x AAA
Visit ExtechBuy now from Amazon
Extech DV2524 – 1000VAC
N/R1000V2 x AAA
Visit ExtechBuy now from Amazon
Extech DV26100 – 1000VAC1000VAC600VAC2 x AAA
Visit ExtechBuy now from Amazon
Extech DV3012 – 600VAC
600VN/R4 x LR44
Visit ExtechBuy now from Amazon
Extech DVA3012 – 600VAC
600VN/R4 x LR44
Visit ExtechBuy now from Amazon
Flir VP5024 – 1000VAC
N/R1000V2 x AAA
Visit FlirBuy now from Amazon
Fluke 2AC90 – 1000VACN/R1000V2 x AAAVisit FlukeBuy now from Amazon
Fluke 1AC-II A190 – 1000VACN/R1000V2 x AAA
Visit FlukeBuy now from Amazon
Fluke 1LAC II A20 – 90VAC
N/R1000V2 x AAA
Visit FlukeBuy now from Amazon
Fluke LVD2 Volt Light90 – 600VACN/R600V1 x AAA
Visit FlukeBuy now from Amazon
GreenLee GT-12A50 – 1000VACN/R1000V2 x AAA
Visit GreenLeeBuy now from Amazon
GreenLee TR-12A50 – 1000VACN/R1000V2 x AAA
Visit GreenLeeBuy now from Amazon
GreenLee GT-165 – 1000VAC
N/R1000V1 x AAA
Visit GreenLeeBuy now from Amazon
Klein NCVT-150 – 1000VACN/R1000V2 x AAA
Visit KleinBuy now from Amazon
Klein NCVT-212 – 1000VAC
N/R1000V2 x AAA
Visit KleinBuy now from Amazon
Klein NCVT-312 – 1000VAC
N/R1000V2 x AAA
Visit KleinBuy now from Amazon
Klein NCVT-412 – 1000VAC
N/R1000V2 x AAA
Visit KleinBuy now from Amazon
Milwaukee 2202-2050 – 1000VACN/R1000V2 x AAA
Visit MilwaukeeBuy now from Amazon
Milwaukee 2200-2050 – 1000VACN/R1000V2 x AAA
Visit MilwaukeeBuy now from Amazon
Milwaukee 2203-2010 – 1000VAC
N/R1000V2 x AAA
Visit MilwaukeeBuy now from Amazon
Santronics Ultimate AC50 – 1000VACN/R1000V2 x AAA
Visit SantronicsBuy now from Amazon
Santronics AC50 – 1000VACN/R1000V2 x AAAVisit SantronicsBuy now from Amazon
Santronics Low AC24 – 90VACN/R1000V2 x AAAVisit SantronicsBuy now from Amazon
Sperry VD650450 – 1000VAC1000V600V1 x AAA
Visit SperryBuy now from Amazon
Sperry VD650512 – 1000VAC
1000V600V1 x AAA
Visit SperryBuy now from Amazon

† All non-contact voltage detectors have an LED voltage indicator light.
‡ Product availability and specs may change. Check manufacturers website for more information.
§ Links may earn us an affiliate commission if you decide to click and purchase. For local purchasing, check nearby electrical supply and home improvement retailers for product availability.

Maximum Voltage Range: A typical single household circuit from the electrical panel ranges from 110-240 VAC. The difference between a 600 or 1000 VAC capable detector will be irrelevant for common homeowner use and only pertains to trained professionals working with higher voltage applications, e.g. outside power coming to the circuit panel.

Low Voltage Range: To check thermostats, doorbells, and the low voltage side of an AC transformer, a low voltage or dual-range detector will be needed, as these components typically operate at 24VAC or lower.


DID YOU KNOW? Depending on the context, low-voltage and high-voltage are relative terms and vary by definition. Understand the type of electricity – mains electricity – delivered to your home.


CAT III Rating: Refers to measurements on hard-wired equipment in fixed installations, distribution boards, and circuit breakers. Other examples are wiring, including: cables, bus bars, junction boxes, switches, and socket outlets in the fixed installation.

CAT IV Rating: Rated test instruments are designed for testing on the primary supply source, which also includes 120V or 240V overhead or underground lines that power detached buildings or underground lines that power well pumps. The CAT IV rating covers the highest and most dangerous level of transient over-voltage.

Empirical Data: Beyond explaining and comparing the common specs between voltage detectors, we also selected and purchased several of the non-contact voltage detectors to include firsthand observations, and we chose a top pick.

  • Each non-contact voltage detector tested had noticeably different audible levels, but none of the products list db levels, which can be an important factor for users.
  • Static electricity was detected by all non-contact voltage detectors, however, the manufacturers took this false reading into consideration. Non-contact voltage detectors will only cause flashes of light and possibly single chirps – instead of a steady light and steady audible alarms for true voltage.
  • A response from Santronic said, “Our voltage testers are manufactured, printed, and packaged in the US.”

Top Pick: Klein NCVT-4 w/ IR Thermometer

Klein NCVT-4IR Non-Contact Voltage Tester
Go to Product Page
View User Manual in PDF Format
Find a Local Dealer
Buy now from Amazon

What to like:

  • A voltage detector may not need to survive the demands of a rugged environment, but I still appreciate the use of thick plastic and heavy-duty construction.
  • Having a screw cap for battery replacement may seem like a small detail, but compared to other brands and models that require squeezing and / or prying the battery cover off, the screw cap is a great feature.
  • You’ll notice the absence of the flat extended tip. The high sensitivity of this detector can detect voltage on all receptacles, including tamper-resistant receptacles, from the surface of the receptacle and doesn’t require a tip or test probes to be inserted into a receptacle.
  • The dual-range capabilities (12-1000VAC) can detect voltage on AC electric throughout the home: outlets, cords, switches, circuit breaker, power strip, thermostats, doorbells (before and after the transformer), humidistat, and security systems.
  • There isn’t a flashlight on the NCVT-4, as the IR thermometer takes up that space, but the Blue LED standy lamp is bright enough to help light dim areas.
  • The IR thermometer is very useful for investigating air leaks and lack of adequate insulation. Is the built-in IR thermometer a proper substitute for a thermal imaging camera? No! But you can conduct surface temperature variation tests to make a few home efficiency improvements.

In Summary: I have always preferred Fluke electrical tools and already own a Fluke T+PRO Electrical Tester which has great features for pro or home electrical projects: detect AC/DC voltage (even without batteries), GFCI trip, and the backlit LED display gives exact voltage numbers (batteries required).

But as useful as the Fluke T+PRO is, the Klein NCVT-4 non-contact voltage detector also has it’s key attributes, and only time will tell if both devices serve enough of a purpose to remain in a DIY home electrical kit.

Advertisement