How to Use a Non-Contact Voltage Tester (2023)

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Introduction: How to Use a Non-Contact Voltage Tester

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A non-contact voltage tester is the safest way to make sure the power is off without touching any wires.

Before you open an electrical box, you should:
- cut off power to the outlet at the main electrical panel
- confirm you turned off the right circuit

(Video) How to Use a Non-Contact Voltage Tester

This is where the non-contact voltage tester comes in handy. The tester will light up and/or make noise when it comes close to a hot (live) wire, even one that's covered in plastic insulation. Note that it can't test through metal conduit or metal sheathing.

Before using the tester, check its batteries the easy way: by shoving the tip into a live electrical socket, or holding it against the cord or bulb of a lit lamp. You'll hear continuous chirps or see a series of flashes to confirm the tester has detected voltage.

When testing a receptacle, just put the tip into the smaller (hot) plug slot. Of course, it's always good to check the larger (neutral) slot in case the receptacle was mis-wired, Make sure you've checked all slots in the receptacle in case they were wired differently or on different circuits, and if the receptacle is connected to a wall switch make sure the switch is on during testing. After you unscrew the receptacle, pull it out and directly test all the wires again to confirm they're not live. It's also a good idea to test any other wires reachable from the back of the receptacle.

When testing a power switch, unscrew and remove the cover plate then place the nose of the tester against the screw terminals on the side of the switch. Once you confirm the wires aren't live, it's safe to unscrew the switch and continue testing other wires in the box.

When testing a light fixture, turn the circuit off at the main panel, and ensure the light switch is turned on. Then unscrew the light bulb, and place the nose of the tester onto the center socket button. If the light has two switches (on a three-way switch), test with one switch in both the up and down position. Once you've confirmed the fixture isn't live, it's safe to unscrew it from the electrical box, pull it out, and test any other wires you see.

For more information on electrical projects check out The Family Handyman - Electrical

- By the DIY experts of The Family Handyman Magazine

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    10 Comments

    How to Use a Non-Contact Voltage Tester (11)

    ErikOlsen

    8 weeks ago

    I got the Smart Electrician one from Menards today. Nothing smart about it. Put the batteries in and there is no chirp but the LED lights up when the clip makes contact with the pad under it but not when shoved into a live outlet, like the one my laptop is plugged into that I am using to write this note.

    Buy quality like Kline or Southwire. If it is less than $10 skip it.

    How to Use a Non-Contact Voltage Tester (12)

    watchmania

    6 years ago

    mine is pretty useless for contact testing. it beeps on live. also beeps on neutral. oh it also beeps on ground. now how do I know which is which? it does correct job contactless on wire sides. but why would I want to test that?

    How to Use a Non-Contact Voltage Tester (13)

    janiceelaine.quandt

    7 years ago

    this is good to know... as a beginner it is agood place to start.

    How to Use a Non-Contact Voltage Tester (14)

    spiderham

    9 years ago on Introduction

    (Video) The DEADLIEST Electrical Tester...

    If you're going to use one of these get a Klein. I've used the Greenlee, Ideal and Craftsman versions and all have given me false reads. I now have 2 Kleins, one at home and one at work, and neither has given me a false read.

    How to Use a Non-Contact Voltage Tester (15)

    Balord

    9 years ago on Introduction

    Hey! I discovered another use for these non-contact testers! In days gone by I have done (as I'm sure nearly any back yard mechanic has) the age old test for ignition spark by either putting a screwdriver in the spark plug socket and turning over the motor and check for visible spark....it does work and in fact an auto repair shop I frequent still does it this way. Or as a younger lad I have been known to do the grasp test on a lawnmower or go-cart plug (OUCH!). These testers make both of those obsolete! And they can be used in any of the situations mentioned by ONE person with ease! Faster too since no removal of plug wires needed. If you have no partner, simply (depending on the type) turn it on or in my case put a rubber band around the clip so force it to 'on' condition. and place it near a plug wire and then turn the engine over, my tester has an audible beep along with the light. Of course if too close to the starter wire and/or alternator my tester will also pick those up but continually whereas the plug wires are intermittent..

    How to Use a Non-Contact Voltage Tester (16)

    Aussie Nuf Man

    9 years ago on Introduction

    I am an electrical teacher at college (apprenticeships) and it is difficult to find anyone (respectable) who would recommend the use of these tools - or Death Sticks as they are commonly called.

    Not only is it 'common' to get false positives but it is also common to get false negatives. I have had mine go off on a hot dry day in Australia by just having it in my tool bag - try rubbing one on your hair (or arm if your hairy like me). Static makes them trigger easily.

    I own a Milwaukee death stick and I know I need to place it very specifically next to the active conductor in 2.5mm TPS (common 'flat' house cable). If I turn the volt stick more than 10 deg or so, there is no reaction. Granted other brands are not as sensitive as Milwaukee however ideally, decent death sticks can find one active cable in a bundle of 20 or more circuits easily.

    As Binnie said - good 'first point of call' but should NEVER NEVER NEVER be used to determine if a circuit is de-energised or not. Take it from someone who has made the mistake and ended us seeing what 230Vac does to the jaws of a $70 pair of pliers at close range!

    Hey Phil B, not sure where your from, but in Aus, I can go to any electrical wholesaler and get a cheap polarity tester for about $12 to $15 - 5 to 10 quid

    How to Use a Non-Contact Voltage Tester (17)

    (Video) Common Safety Issue | Non-Contact Voltage Testers

    binnie

    9 years ago on Introduction

    I would not rely on these non contact sticks, they are a good place to start checking if a circuit is dead, however they are not to be trusted!!

    How to Use a Non-Contact Voltage Tester (18)

    Isaac Laserman

    9 years ago on Introduction

    I don't think this instructable is really necessary. I t is well made though.

    How to Use a Non-Contact Voltage Tester (19)

    normanschneider

    Reply 9 years ago on Introduction

    Ironically I just purchased one of these voltage testers for a home repair project. Up until now I was using the el-cheapo contact style with bulb but needed something to test over shielded wiring.

    For some of us who are relatively novices and share a healthy respect for electricity, I appreciate the comments on the proper use of this tool. Too often the manufacturer will package a device without sufficient guidance, assuming a working knowledge.

    For example, the author's comment around testing the neutral in case of mis-wiring, which can occasionally happen. Also liked the different use-case scenarios described.

    I, for one, would love to see a sub-section on household tools (like a wiki) that describes use-cases, selection, care, alternatives and caveats.

    How to Use a Non-Contact Voltage Tester (20)

    Phil B

    (Video) How To Use a Voltage Tester | Ask This Old House

    9 years ago on Introduction

    I decided to purchase one of these after using one my daughter bought. I used it to get the polarity right when replacing the outlets in her house. It was very handy, especially since the old wires were coated in black rubber, not white and black plastic. When I looked at them in a store, there were several models in quite different price ranges. I learned the difference is the sensitivity to both high and low voltages. I chose one that would allow me to troubleshoot the low voltages along a string of Christmas mini-lights. I also noticed the less expensive units required relatively expensive button batteries, while the more expensive units accept regular common alkaline cells.

    FAQs

    How does a non-contact voltage tester work? ›

    How do non-contact voltage testers work? Non-contact voltage testers work by sensing a very small amount of current that is capacitively coupled from the live circuit to the tester and back to ground. Non-contact voltage testers light up when they detect this current without needing to make direct contact.

    How do you use a voltage pen tester? ›

    You merely need to touch the tester's tip to the wire or, if you're testing an outlet, place it on the faceplate of a shorter plug hole to use a non-contact voltage tester. To demonstrate there is voltage, the majority of testers will either light up or make a sound.

    Can you trust a non-contact voltage tester? ›

    Assuming you have a good, trustworthy device, it'll do a good job of letting you know if a 120- or 240-volt circuit is live. Probably. These devices are not 100% accurate, but they do a pretty good job. You simply hold the tip near a suspected circuit, and it'll tell you if there's current or not.

    How do you use a commercial electric non-contact voltage tester? ›

    A: There's no need to touch a live wire. Simply hover the tester over the wire you are investigating and if it has voltage, it will beep.

    How do I test if a wire is live? ›

    One of the easiest ways to know if a wire is live is to use a voltage checker or a current checker. These are simple devices that you can touch to any wire, and it will tell you if there is electricity running through it.

    How do I make sure my voltage tester is working? ›

    To use a voltage tester, touch one probe to one wire or connection and the other probe to the opposite wire or connection. If the component is receiving electricity, the light in the housing will glow. If the light doesn't glow, the trouble is at this point.

    Why use a non-contact voltage tester? ›

    A non-contact voltage detector is a device that can detect the presence or an electrical charge in a wire, cable, or piece of equipment without having to touch the object. Voltage detectors are primarily used by electricians and electrical technicians.

    How to test a light switch with a non-contact voltage tester? ›

    To test a non-contact voltage tester, hold the tool near an outlet you know has live power and make sure it senses the current. To test a continuity tester, attach the tester clip to the tester's metal probe; the tester should light up.

    Can you touch a live wire with a voltage tester? ›

    Always remember: Making contact with an electrical voltage may result in electrical shock, burns and serious injuries, or even death, because such are the effects of an electrical current when it flows through a human body. In practice, no electrical wire or electrical component is completely safe to touch.

    What is a safe voltage to touch? ›

    In it's guidance 1910.269(I)(3)(i), The OSHA states in table R3 that anything up to 50Vac is a Safe Working Voltage.

    Can a non contact voltage tester give a false positive? ›

    Some non-contact voltage testers can show a false positive or negative if: They are not built from quality components. The insulated test point touches grounded metal. The cable being tested is partially buried.

    Do non contact voltage testers work through walls? ›

    They're called "non-contact", but that means no electrical contact (i.e. they don't have to touch the bare wire). You'll just about have to touch the tool to the insulation of a wire for them to work properly, so it's not likely you'll be detecting wiring within any type of wall with one of these tools.

    Can you use a multimeter as a non contact voltage tester? ›

    Just to be clear, if by “non contact” you mean that the two leads connected to a typical multimeter are not to make directly electrical contact with a given voltage source, whether the voltage source is AC or DC, there is no way for the meter to provide a reliable voltage measurement.

    How do you check a live wire with a screwdriver? ›

    In order to test the live wire, the user's body must be in contact with the metal cap on the top of the screwdriver when the tester is put in contact with the wire. This completes a genuine electrical circuit and the bulb will light up once the tester senses voltage.

    Will I get a shock if I touch neutral? ›

    If you have a broken neutral YES you will get an electrical shock. The neutral is at the same potential as the ground in most electrical standards around the world, so if your wiring is done right and tested it should be safe to touch the neutral, accidentally ONLY.

    What happens if you touch a live wire? ›

    Coming in contact with an electrical voltage can cause current to flow through the body, resulting in electrical shock and burns. Serious injury or even death may occur. As a source of energy, electricity is used without much thought about the hazards it can cause.

    Can you test a breaker with a voltage tester? ›

    Touch one prong to the circuit breaker's terminal screw and touch the other prong to a ground screw, usually on a metal bar along the right side of the circuit box. The multimeter should read a between 120 and 240 volts. Anything else indicates a faulty circuit breaker.

    Can you put a volt tester on an outlet? ›

    A two-prong voltage tester is also called a multimeter and can be used to check the wiring and grounding on the outlet. To check an outlet, adjust the knob to the “AC” function. The black probe should go into the wider neutral slot. The red probe then goes into the narrow hot slot.

    How do you test a light fixture with a voltage tester? ›

    To test a powered light socket, turn the power to the fixture on. Remove the mounting screws and lower the socket, then set the voltage tester to read AC voltage (at a value that's the lowest to but greater than 120 VAC).

    What is the advantage of a non contact voltage detector over a voltmeter? ›

    What is the advantage of a noncontact voltage detector over a voltmeter? It does not have to contact the energized electrical circuit to indicate voltage.

    What is the range of non contact voltage detector? ›

    Non-contact voltage detection from 100V to 600V AC. Provides audible tone and LED indication when voltage is detected.

    When measuring unknown voltage what must you do? ›

    When measuring an unknown voltage, select the highest range and work down. 2. Touch the negative probe to a known ground (the chassis of the car) and touch the positive lead to the wire you're testing. For accurate readings, make sure your ground point is bare metal (no paint, rust, etc.).

    Why do I have voltage when switch is off? ›

    Just to recap, a "phantom voltage" is where a wire from a switch to a light or outlet runs next to a permanently live wire, when the switch is off, the AC voltage in the other wire can induce a voltage in the switched-off wire.

    How do I use a beginners multimeter tester? ›

    Place one probe at each end of the circuit or component you want to test. It doesn't matter which probe goes where; resistance is non-directional. If your multimeter reads close to zero, the range is set too high for a good measurement. Turn the dial to a lower setting.

    What are two types of voltage tester? ›

    To test a live wire, you need a non-contact voltage tester or a pen voltage tester. The non-contact voltage testers detect the current at a far distance. Hence, you will only place it at proximity, and it will detect if any current is flowing in the wire.

    Can you get shocked without being grounded? ›

    You can even receive a shock when you are not in contact with an electrical ground. Contact with both live wires of a 240-volt cable will deliver a shock.

    Will a hot wire shock you? ›

    Touching a hot wire allows energy to flow through your body to where your feet touch the ground, causing an electric shock. Electric shocks occur when electricity can enter and exit your body through two contact points.

    How can I tell which wire is hot without a multimeter? ›

    2. Method – Using tester screwdriver
    1. Get a voltage detector screwdriver. ...
    2. Turn on the screwdriver by pressing the power button.
    3. Touch the probe of the screwdriver to the wire.
    4. If the detector lights up, then there is electricity running through the screwdriver.

    What kills you amps or volts? ›

    Amperage is a measure of the volume of electrons. An electrical current at 1,000 volts is no more deadly than a current at 100 volts. But tiny changes in a current's amperage can mean the difference between life and death when a person receives an electrical shock.

    What is the deadliest voltage? ›

    Assuming a steady current flow (as opposed to a shock from a capacitor or from static electricity), shocks above 2,700 volts are often fatal, with those above 11,000 volts being usually fatal, though exceptional cases have been noted.

    How many volts is lethal? ›

    A good rule of thumb is that when a shock is at or above 2,700 volts, the person often dies or experiences severe injury. At over 11,000 volts, the victim will usually pass away.

    What causes ghost voltage? ›

    Ghost voltages can be caused when energized circuits and non energized wiring are located in close proximity to each other, such as in the same conduit or raceway. This condition forms a capacitor and allows capacitive coupling between the energized wiring and the adjacent unused wiring.

    Can a non-contact voltage detector detect DC? ›

    Test quickly for energized circuits, detect AC and DC voltages with non-contact volt detectors available from Specialized Products. They are safe and allow you to avoid exposure to high voltage electrical shock or personal injury.

    How common are false positive tests? ›

    During the same period, there were 5,079 negative tests; thus a total of 5,110 tests were carried out. The false positive rate (single gene low level positive) in this period was 0.5% (26/5110), giving a specificity of 99.5% (5,079/5,105). Over the same period, the true positive rate was 16% (5/31).

    Can you stick a voltage tester in an outlet? ›

    Shut the power off to the outlet. Put the end of the voltage tester into the hot slot on the outlet. The hot slot is the narrow side, while the wider slot is the neutral side of the outlet plug. You can also pull the outlet receptacle out to do additional testing.

    How do you test if a wire is live without a voltmeter? ›

    2. Method – Using tester screwdriver
    1. Get a voltage detector screwdriver. ...
    2. Turn on the screwdriver by pressing the power button.
    3. Touch the probe of the screwdriver to the wire.
    4. If the detector lights up, then there is electricity running through the screwdriver.

    Can you get electrocuted using a multimeter? ›

    Therefore, it is possible to get electrocuted by using a multimeter.

    Do you need a non-contact voltage tester? ›

    A non-contact voltage tester is the safest way to make sure the power is off without touching any wires. This is where the non-contact voltage tester comes in handy. The tester will light up and/or make noise when it comes close to a hot (live) wire, even one that's covered in plastic insulation.

    Can you touch black wire without getting shocked? ›

    If you come in contact with an energized black wire—and you are also in contact with the neutral white wire—current will pass through your body. You will receive an electrical shock. You will receive a shock if you touch two wires at different voltages at the same time.

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