How To Use a Voltage Tester | Ask This Old House
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- เผยแพร่เมื่อ 6 ก.ย. 2024
- In this video, Ask This Old House host Kevin O’Connor and master electrician Heath Eastman discuss the different uses for voltage testers, as well as test some of Heath’s favorite models.
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Kevin O’Connor meets master electrician Heath Eastman at the shop to discuss the different types of voltages testers and their uses. Heath has four types of testers to show Kevin, including a non-contact pen tester, a full-size multimeter, a miniature multimeter, and a plug-in tester. Heath explains how each tester works, which scenarios they’re best for, and how he uses them in his work line.
Contactless Voltage Tester [amzn.to/3kZ4VSm]
A contactless voltage tester is shaped like a pen or marker, and it can indicate whether a wire or outlet has voltage feeding it. They’re quick and easy to use, and they can help an electrician or homeowner locate live circuits. However, they don’t tell the user how much voltage the outlet or wire has, and they’re not always completely accurate.
Full-size Multimeter or Contact Tester [amzn.to/30KxzQg]
A full-size multimeter might be overkill for homeowners, but they can tell an electrician a lot about an outlet, switch, fixture, or circuit. These voltage testers have two contact points or probes that the user can touch to the wires in a circuit to determine the amount of voltage, amperage, and resistance on the line. If the pen tester alerts to a circuit having a charge, a contact tester is the best way to find out why.
Small Contact Testers [amzn.to/2Zfr1bu]
A homeowner doesn’t necessarily need a full-size multimeter, but a small contact tester can do much of the same work. These scaled-down meters have two contact points or probes, and they explain the voltage on a system in ranges, such as 24 volts, 48 volts, 120 volts, and 240 volts. They’re more affordable than full-size meters and much more compact. They’re also one of the only options for 2-prong outlets.
Receptacle Testers [amzn.to/3cEXZVC]
Receptacle testers are compact and easy to use, and they provide a lot of information. While they don’t explain how much voltage a receptacle is experiencing, they do explain if there is an open ground, an open neutral, or an open hot. They can also indicate polarity, or whether the hot and ground are reversed, or (more commonly) if the hot and neutral are reversed. These testers will only work on 3-prong outlets, and they can test GFCI outlets, as well.
They All Have Their Merits
All types of voltage meters have their pros and cons, and it could be worth keeping a few types of testers in your tool bag. While the receptacle tester is the only tester that tests polarity, it can’t quantify voltage or test two-prong outlets. Pen testers or contactless testers don’t explain voltage either, but they’re fast and easy to use. For the best results, have a few of these testers on hand before doing electrical work.
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How To Use a Voltage Tester | Ask This Old House
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A very important point about non-contact voltage testers (NCVT) was not mentioned: Prior to using a NCVT, it is extremely important to test it on a known “live” voltage source to verify that the tester actually works. This needs to be done each and every time it is used. If the tester fails to illuminate when testing, it could be because the tester has a low battery or is defective. In that case, it would fail to warn you about an actual “live” wire. That is why you need to verify that it actually detects voltage before using it for decision making. I cannot overemphasize the importance of doing this.
Most non contact testers have this feature built right in to the device. It will chirp when you initially press its test button, letting you know that the batteries are working, and you're getting a proper test result.
You can hear his chirp and light up each time he uses it in this video.
1 st off , it is Not a voltage tester !
It is a no contact current detector , it doesn't measure voltage...it senses the presence of the electromagnetic field on the hot conductor wire of alternating current. We Electricians call them tick tracers , too hunt down where a hot conductor might have burnt or cracked separated .
@@madatown
That’s nice. The two non contact testers that I have don’t chirp. In fact, the user guide explicitly states that to use the device safely, the proper operation of the device must be verified on a live circuit before each use. Because electricity cannot normally be seen, electrical safety cannot be taken for granted.
@@rrfields65 Regardless of all of that which you have stated, they are sold as and commonly referred to as NCVT (non-contact voltage testers). The presence of that EM field which causes it to light up and/or beep/chirp is an indicator that there may be voltage present on the conductor. So you are indeed testing for AC voltage but not a specific number of volts.
@@illestofdemall13 : Ohm's law :
1 volt x 1 amp = 1 watt
Voltage= the speed of electrons traveling thru a conductor.
Amperage= the number of electrons being pushed thru a conductor.
So many appliances are wired as reverse polarity, Ive been zapped so many times by everything from DVRs to Stereos. Always completely unplug any appliance before removing the cover and working on it!
Even if wired properly, power will come into those devices and zap you. The bottom line is that before you work on things, you need to unplug plug-in devices or turn off the breaker to wired devices.
That's capacitance. 🤣
Those typically use figure 8 connector which means they can plug either way. You should always unplug before you open the case. What on earth were you thinking? Many times? That is suicidal. If you need to work on live equipment use an isolation transformer.
Kevin is an excellent host. He asks great questions that us novice folks need answers to. 😂
he is not so amazing. His point of ''THIS IS CONFUSING'...says it all. He has job here as host because...remember this......he's white. get it?
notice DANNY.......no one on show that looks like you. Know too the questions were contemplated as a script sorta. I think he's kinda slow, almost dense. No minorities in boston; reason I stopped subscription to magazine
And what have YOU ever done for anyone? Just another whiner looking to tear others down.
That's one of the better explanations for why getting the polarity correct in the outlet is important. I bet this was a follow-up to the previous video they did on this, where Heath used to washing machine example and it was hard for some people to understand what he meant when he said that it could be off, but power could still be running to it.
*Jesus loves you*
Great info. It will probably save someone's life.
Maybe mine. I was trying to figure the odd reading out on one of my outlets.
Before you test a live circuit with a multimeter, put the meter on the lowest ohms setting and touch the leads together. They should read zeros across the display. If not, one of the leads is broken. After you confirm you have zeros on the display, the put the meter on ac and test the circuit.
I would love to see a followup vid on using the multimeter to test a light switch or continuity check when power is off.
Thank you TOH for covering something seemingly basic but could “trip” up any homeowner. I’m definitely adding a reverse polarity tester to my tool bag.
Something super important about those contactless voltage testers that was not mentioned is that they are very short range and they are blocked by a Ground or Neutral conductor. If you use one on a jacketed wire like NM-B (Romex), you can tell which side the Live conductor is on. The same with an extension cord with it's twisted conductors. You can follow the twist down the cable. *This means a quick tap will not necessarily cause it to light up so you might cut through a live cable.*
As an electrician I carry a number of tester with me, including the first 3 types. I also have receptacle testers, one which tests and times GFCI trips as well as an AFCI tester; if you’re going to get a receptacle tester spend the extra to get a GFCI tester at a minimum. Also be careful with sum of the cheaper non-contact and direct contact testers as you can actually get sum parasitic currents/voltages on a line that can be too low to indicate yet still enough to hurt you. I carry a less expensive contact tester as it’s easier than pulling a meter out and unwrapping the leads but a decent True-RMS multimeter is something every homeowner should have. These aren’t expensive things, in fact I use these things along with some cheap tools and a tool box as a home warming gift for family and friends as these are a must have along with screwdrivers, pliers, and a hammer. Giving the basics also saves on having to go help people as they’re in the position to help themselves.
Bought the 2 simple ones he mentioned about a year ago. Work great when I moved into my new house and replaced light fixtures. Great peace of mind.
Great information and comments. The 3 prong GFCI tester is definitely a good one to have. There is a new version out that also has an LCD screen that actually gives you a voltage readout on the screen that comes in handy. I believe it is made by Klein….
Thank you for this video! I feel that new people in the trade need to have a basic understanding of how electrical testers work! Heath is a great electrician and I hope to meet him someday! Keep up the great work ATOH!
Can you have a more detailed video about the multimeter tester? ty
I watched this is see how to use the only one they didn't use. The multimeter! go figure! Thanks for nothing! LOL
No, he had a multimeter! He just didn't have a professional electrician
A/C current and voltage clamp meter!
@@rrfields65 tbone didn’t say anything about clamp meters, neither are they necessary for the job.
@@Engineer9736 : like hell they ain't! How are you going to test amperage draws on A/C circuits !???
@@rrfields65 The entire video is about voltage testing. It’s with font size 100 on the introduction picture.
@@Engineer9736 : the ONLY voltage testers there in the video is the 2 lead direct contact tester , which lights up on the LED of the scales 120,220,240vac and the multi-meter.
Bought a DVR years ago 3 prong wiring, plugged it in and touched the metal housing and got zapped! Found out it was wired wrong in the breaker box, white wire and black were switched when house was built 30 years ago. Lamps etc. worked fine. So it's wise to buy that unit that checks polarity as shown.
The DVR was wired correctly. The outlet was wired incorrectly. The neutral was bonded to the ground. The neutral was swapped with the hot at the panel. Therefore all the grounds became hot including the metal DVR box. Very dangerous.
@@JustinL614 It was wired wrong in the breaker box. Same difference.
@@anton1949 I was responding to a comment that said the DVR was wired wrong. I think the comment was deleted. Also, it's not the same difference. If it was only that the hot and neutral were swapped in the panel you wouldn't have gotten shocked from the box.
@@JustinL614 I noticed that also, everyone should check all outlets, assume nothing. I learned my lesson.
@@anton1949Well I'm glad you didn't get hurt or have a fire start. As an electrician I' just extra cautious. I find stuff all the time in homes that are wired wrong. As you pointed out, alot of things work even though theyre are not done right.
Going to sign the paperwork for my first house which is an older house. This is invaluable information, thank you.
good to know about the reverse polarity - the previous owner of my house and incorrectly installed the outlets so a large majority of mine were wired in reverse.
Extremely important information. I think every homeowner should watch this video. Even if you don’t mess with electrical current. You should always RESPECT ELECTRICITY.
Literally just learned something about the wiring reversed. I've been doing wiring for a while and never made the mistake. Never knew what would happen if done wrong
Definitely need to make an updated video showing the Klein Tools RT250 receptacle tester! Way more features than the one shown in this video!
*Warning* If you bought that yellow Klein tool, check with home depot or Klein because some were recalled! The on button may not work and you may think there is no power, when it is live, causing possible electrocution! You should always check your tool on a known live circuit to make sure it works-flashes or beeps! This is serious stuff! If you are not sure of your ability, hire a professional to do it right!
Are you talking about the tick tracer ?
@@rrfields65 Yeah, he/she was talking about tick tracer, aka non-contact voltage tester ;)
Wow that was an awesome explanation of how to test for electricity. Next time Im in Home Depot Im picking up one of those 3 prong testers.
What can you use when you're at the main panel and you're trying to determine which switch cuts power to a specific outlet from a distance?
A circuit breaker finder. They work great. This the one I bought and use. There are others made by different manufacturers. It works great.
Klein Tool ET3000
@@murdstonecardinal3355 THANKS. Exactly what I need.
I don''t own nor have used any of these, but will pick these up when I'm at Home Depot. So, I have a few questions regarding to the video above.
1) With non-contact tester, does it matter which hole you point into to test ?
2) With contact testers (2nd and 3rd item), they both have RED and BLACK pins, how do I know which color goes into which hole, or it doesn't matter?
Thanks.
1. Doesn't Matter, most non-contact testers will go off when your close to the outlet. Doesn't hurt try try both it your worried.
2. Black goes in the Neutral (larger slot), Red in the Hot (smaller slot). Also, never touch the metal part of the probes, if you have one plugged to the receptacle, the other one maybe hot. Always put the black neutral probe in first, take it out last.
Ideally for NCV you'll point/touch at the smaller of the two vertical pins. That is the hot. I would check all 3 "holes" because why not.
With the digital multimeter on AC, black and red don't matter. AC would be shown as V with a squiggly symbol (~ tilde)
It tests the hole you are testing.
@@teeing9355 If they lit close to the outlet you have a reverse bootleg ground. It is very dangerous. They really have to put it in. It is so insensitive. That means a tester for US outlets does not work in Europe.
WooooooooW😳thanks for this vid. I wasn’t 100% confident in knowing if I wired my new smart dimmers and gfci(s) correctly so I was “oh well, they work and I’m tired now so forget it”🤷🏼♂️but after seeing this vid and learning the warnings and potential dangers, I’m redoing all of them tonight so I can feel 100% sure and have a piece of mind!! Wheeew! Thx
This has been the most educational video for me. Thank you so much for sharing this.
You guys should do a video on electricity basics and how to wire outlets showing how to use the testers as well. …if you haven’t already
Good stuff from Heath, as always - have used a couple of these - the "little guy" is worth its weight in gold - has indicated a reverse polarity in one of my kitchen outlets - highly recommend getting one...
It’s also a fire issue. Fuses are also placed on the hot side. If it is reversed an internal fuse cannot clear a fault condition.
Theoretically the breaker should catch it, except if the short is a low current short exceeding the capacity for internal components it may not exceed the breaker capacity so the fault will continue until unplugged or the breaker is flipped.
Bull, almost all electronic devices use connector that fits either way. Lamps do not have fuses.
@@okaro6595 if they fit either way that means the system either lacks protection or is designed to have fuesable links on both sides.
The reason non reverseable plugs exist and one blade is bigger than the other is to ensure the hot line is connected to where a fuse or other state is for safety.
In lamps as your example without fuses it has to do with making sure the external part of the bulb is neutral not hot so in the event you touch the base of the bulb you won’t get shocked.
So go troll somewhere else. How many UL certified products have you worked on? Have you even done the process? I have.
Ya'll have the BEST explanatory and professional videos. Keep up the good work (of course always Liked & Subscribed) John 3:16
Good explanation, I have a professional Fluke multimeter, overkill for an average home owner. I use it for auto mechanics.
I love that he plays dumb on our behalf. All the questions get answered and it makes for a perfect video. Thanks.
excellent communication between the two and great information and questions asked. great video and interaction
The small contact tester link opens up to a vehicle tester, not the one shown
I have that middle contact tester and I found it worthless. Give me a multimeter any day. The non contact tester is amazing. I was adding a outlet and had the power off. The box had a second hot wire and I only found out because of the none contact tester
This Video is so informative Thank you very much for it!
If you have two prongs, get an electrician to add ground wires or a GFCI. You might save yourself a nasty shock.
I'm not a professional.
If you have a two prong outlet you can't plug in 3 prong appliances so there is no need to worry.
But if you want to use 3 prong appliances in my opinion the best thing to do is to add a ground wire and 3 prong outlet which can be a big job.
GFCI is an option instead of ground wire but you don't get the advantage of reduced electric fields the ground wire gives.
@5:33.....slow beeping means no power?
Always love learning things
And this was a problem I had
Thanks so much
Very helpful, thank you!
What happens if you want to test the wires connected to a light fitting?
Like it alot!!! Great Info about Reverse Polarity
I don’t do any electricity work at all but this video is very informative!! 👍🏻
This makes so much sense. Thanks for posting.
this show is simply great.
This was very informative. Thank you
There are also screwdrivers which have a neon lamp in the handle.
Klein digital plugin is the best other than a DMM meter $19 model RT250
back the basics... nice
An excellent, excellent video!
Thank you!
How are these with the child resistant/tamper proof outlets?
Which prong goes what side
Dang! I might just understand this stuff eventually. Thank You.
No phantom readings from 4 lights thing??? how about when you checking the outlet and neutral leg is disconnected somewhere in the walls or by the circuit breaker box. I personally recommend neon screwdriver tester or a good meter
Then you test hot to ground not hot to neutral. Any multi-meter can get a phantom reading unless you have two points to test between. A NCVT will detect a hot without a need to test across two points.
@@JustinL614 ... true, but those will only give you a go / no-go indication of power. To do trouble shooting you need a meter. (and more education)
@@rupe53 I know but the original comment was about a hypothetical situation where there is a hot but no neutral. I went further by describing a scenario where there is also no ground. I agree a good meter is the best and I realize this situation would be way beyond someone who lacks the knowledge of troubleshooting. I would probably just turn all the breakers off and then use a tone tracer to find the wire in the panel.
Helpful vid. Thanks TOH.
How does this work for light switches?
I have a problem of opening the cover to put the battery in
Great easy to understand video!
Great point
Thanks
Interesting. Very mutch so. Great content yall
That was great info. Thanks for that video
Great video!!!!
He didn’t say if the red/black matters in terms of where u put them (or for something other than a socket)…?
Why no links so easier to find these products or the names of them in the video's description?
Just checked the video description & I see name for each item and correct links for the 1st (contactless tester), 2nd (multimeter), and 4th (receptacle tester) item.
The third amazon link looks wrong to me (automotive circuit tester?) but more importantly (Props to This Old House) they provided the technical names for each tool.
1. Contactless Voltage Tester
2. Multimeter (Full Sized)
3. Small Contact Tester
4. Receptacle Tester
(Check the description for an explanation of each tool's uses)
5:24 ya i have to rewatch this.
Very good
You guys are awesome .
I use an Simpson 260😁
Is he poking those probes in both slots of the recepticle or just one?
always must have tools when dealing with ac dc power
So informative.
Good luck trying to use the single point non contact tester in tamper resistant receptacles.
Very helpful
Have had a meter for years and still don't think I fully know how to use it.
Great video
If you're never going to trust a NCV tester then why use it? Why not just use the tool you trust?
Awsum Video
Just don’t stick your fingers in a lamp fitting LOL. Unplug if you really need to for some random reason. Here in Europe you can plug appliances in either way anyway, even the grounded plugs. It’s more of a neat habbit to wire it consistently than of actual use.
Polarized plugs have been used here in the US for 60+ years to reduce the risk of shock from lamps, toasters, etc.
@@illestofdemall13 Toasters have two pole switches.
He never show the multimeter how to do the reading in those outlets?
Nice 👍
I know that this is off subject but I can't help commenting about how MUCH Kevin looks like 1940's actor Van Johnson! I mean he could be his twin. Check it out!
Oh no I’ve gone cross eyed
I think a 6 minute video is enough to start testing electrical wiring. 220 volts is fun to play with two hots. But you watched this video.
Receptacle testers - You have to be careful about the tester saying the ground is good. People that don't care about safety will put a short piece of wire connecting the ground screw to the neutral screw. If wiring in the house doesn't up to code a lot, then I would also take the cover off and look at the screws to be safe.
A socket tester is for casual testing. A proper test would include testing he ground loop impedance. The tester might show there is ground even if the impedance was way too high.
What’s that cute lil thing called?
👍
What is meant by “socket”, “center pin”, “shell”? Still quite confusing, but thanks for your best attempt.
Socket or outlet is slang for duplex receptacle, and look at the bottom of a light bulb ... the tip is the loadside ( current in ) and the " screwshell is the neutral return out .
In terms of a light bulb, the socket refers to where you install the lamp into the fixture. Looking into the socket you will see 2 pieces of metal. A small metal button in the center and a metal shell lining the outer side. Both pieces will be insulated between each other and the outside of the socket. You will notice that the outer metal is twisted like the threads of a nut. Looking at the lamp you will notice that bottom outside part is twisted like a screw. The lamp is designed that way to hold the lamp in the socket when you twist to install it. Looking at the base of the lamp you will notice a piece of metal that protrudes from the base of the lamp. It makes contact with center button inside the socket.
When the light fixture is energized. Current will travel to the center button enter the lamp and exit through the shell.
He’s refering to the bit of the lamp where the bulb screws into. The threaded part = the shell, the small metal dot at the far end = the center pin.
@@Engineer9736 A better description than my rambling. K.I.S.S. - thanks
@@rrfields65 Socket isn't referring the a duplex receptacle in this video. Heath was specifically talking about the lamp socket.
How many people's live would be saved from this video?
Thank you Kevin for making professional electricians look like idiots!
Is Scott part of the show anymore?
He posted long ago that his contract ended and was not renewed.
Why didn't thre second guy do the video? He seems to know more about the testers and has been terrified by them.
Hi
I'm sorry, but a tutorial on how to use the voltage meter too would have been much more informative
While you're not wrong, this is more of a "quick tip". Explaining how to make good use of a DMM would take the entire 25 minute program.
@@oambrosia For testing the electric installation of a house you only need 1 setting: AC. Earth to neutral should measure 0v, earth to hot should measure the line voltage. Neutral to hot should obviously show the line voltage as well. With those 3 measurements you have checked everything that that 3-LED tester does. If neutral to hot shows voltage but ground to hot doesn’t, then the ground is NOK. (But if it does show a voltage it still doesn’t guarantee that the ground is OK; you need complicated pro equipment for that with prongs that go into the soil outside)
@@Engineer9736 The problem is you can't stick the probes inside a tamper resistant receptacle, which are used a lot in the US.
Would reverse polarity cause an issue with toasters too? I'd guess yes. Way easy to get shocked there.
in older homes with Formica counters that had the chrome band on the front that metal was usually grounded by the sink. If your appliance was plugged in backwards or the outlet was wired in reverse, you got a shock. This is another reason that countertop appliances are plastic on the outside these days.
@@rupe53 Lol exactly. Don't you just hate when people say "the white wire is the neutral it won't hurt you"? I hear it all the time and it drives me nuts.
@@JustinL614 : the neutral wire will never shock you if it is wired correctly! Electrons hate a resistance path ( you ) to run back home to momma ( electric company generator ) ! Now if you cut that preferred pathway and grab both ends with both of your hands , you are now a resistance load path inline!
Reverse polarity does not matter. Here in Europe (even double the voltage on a single phase compared to USA) you can plug plugs in either way, even the grounded ones. It’s more of a neat thing to wire it consistently than of anything actually useful. Of course you should not poke your fingers into lamp receptacles when the plug is in the wall. The metal of a toaster should be grounded & not in contact with either neutral nor phase.
@@JustinL614 ... key words SHOULD be neutral and SHOULD be working / wired properly.
Several goofs. I retired from a large company with strict safety rules. We had to test the contact less tester to a known power source test the circuit then retest on know power source. We had a battery operated power source made by Fluke to test Multimeters. Sevetal times I had test leads break or work intermittently. Please tell us where in the NEC a nuetral is mentioned. In my code book they only use the term grounded conductor. Had conract less testets give false positives. Light & buzzer would come on. Was due to having 15 to 20 energised wires in a long cinduit then a 70' long trough. When the circuit breaker for motor I wanted to work on was turned off and wires removed from bottom of starter still was telling me wires were energized. The other energised wires induced a small voltage that was pucked up by contact less tester.
Can you do one when is open ground pls
1 multi-meter or 3 specialized items... ya I'll keep my multi-meter
There is another mistake TOH, it is not reverse polarity. In ac circuits, your polarity is reversing 60 times a second meaning one side is negative and then 1/60 of a second later the same side is positive hence AC current.
The fault is the fact that ground is always the white wire and what has happened, you are now grounding the black wire. I'm not going into the simple facts of the grounding in three pronged devices because it will just confuse you and the electrician.
Just as a reminder follow the color codes in 240 v split phase ac and remember the polarity reverses by itself every 1/60 seconds. You should do better research.
Ah, more confused then before,🤣