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Buying Guide: Non-Contact Voltage Detectors

A non-contact voltage detector is a simple, safe, and relatively affordable device to detect the presence of voltage.

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Santronics Ultimate AC Voltage Detector

A non-contact voltage detector is a simple device to safeguard from electrocution.

Using only the tip of the detector, touch a cord, bare wire, or insert the tip into an outlet. The tip of the detector will glow if power is present. Some models also give off an audible alarm when power is detected.

Replacing a switch or receptacle: I’m guilty of using a small appliance as a power indicator to confirm that I’ve turned off the proper power breaker before replacing a receptacle. Not 100% safe – and I no longer use this method. Voltage detectors have a tip that fits inside the receptacle – or touch the terminals – to detect power, and are 100% safe.

Check open ended wires: If you ever locate or discover open-ended wires, you want to know if power is present before addressing.

Power strip troubleshooting: A power strip may have one or more outlets that are not working. You can test if the power strip itself is receiving power or an individual outlet is not transferring power.

Investigate for broken wires: Go along a power cord or path of a wire with the tip of the non-contact voltage detector to find the power disruption. When testing power cords – keep in mind that the internal wires wind together. You may have to move the detector around or along the cord to find the live internal wire.

Spiral Wound Electrical Wires

Common Terms and Descriptions

Voltage Rating: A typical single household circuit ranges from 110-240 VAC. The difference between a 600 or 1000 VAC detector will not be an issue for common homeowner use. The high ratings are for trained professionals that want to read full voltage coming into circuit panels, etc.

Use a low-voltage detector or dual-range dector to check thermostats and doorbells (after the transformer), which are typically rated for 24 VAC and lower. Automotive electrical systems also fall into the low voltage category; ranging from 12-16 VDC.

WARNING: Electrical Hazard. US household outlets range from 120-240VAC and can cause serious injury or death. Turn off power at the breaker panel when working. Contact a certified Electrician or HVAC tech if unsure of your DIY capabilities.

CAT III: 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: 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.

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Comparison Guide

All non-contact voltage detectors have an LED voltage indicator light and replaceable batteries.

We tested a few brands (Milwaukee, Klein, Santronics, Fluke) and discovered the following:

  • Each brand had different audible sound levels. I would like to see manufacturers list the db level in their specs as it can be an important factor.
  • Milwaukee non-contact voltage detectors had the brightest work light.
  • Static electricity was detected by all testers, however, the manufacturers took this false reading into consideration. Non-contact voltage detectors will only causes flashes of light and single chirps – instead of 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.”
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