I don’t use screw-on wire nuts very often, but I still don’t like them very much. They’re not difficult or slow to use, nor are they expensive, so I’m actually not sure why I don’t like them.
What I do know is that I really like using Wago’s PushWire Wall-Nuts connectors (773-series). Wall-Nuts come in several sizes, from 2-conductor up to 8-conductor. I purchased 2-, 4-, and 6-conductor Wall-Nuts and recently started using them on a small project with 16-gauge stranded wire.
Advertisement
Related: We also reviewed Wago Lever-Nuts, which are better but more expensive connectors.
PushWire is fairly accurate as to how these Wall Nuts connectors work. The connectors have an internal spring that spreads and clamps onto wires that are pushed inside.
Step 0: Disconnect power to the wiring
Step 1: Strip off ~0.47″ to 0.51″ of insulation
Step 2: Push connector firmly into connector
Features and Specifications
- 18-12 AWG solid
- 16-12 AWG stranded (19 strands max)
- 22-16 AWG topcoated stranded
- Max Voltage: 600V (building) 1000V (fixtures and signs)
- Max Current: 20A
- Max Temperature: 105°C (221°F)
- Use only with copper wire
- UL-listed
- Test port for continuity check
- Built-in insulation stripping length gauge
For temporary installations, Wall-Nuts are removable and reusable when used with solid wire. When used with stranded wire they must be discarded if wire removal is desired.
Wall-Nuts create a very solid mechanical and electrical connection, and there’s no learning curve. Simply strip the wire to a hair less than 1/2″, and push the wire right in.
Advertisement
I suppose the 19-strand limit for stranded wire is because smaller and more flexible wire might jam up and flex instead of forcing the internal spring to open.
I was successful in using 23-strand 16-gauge machine tool wire, and found the connection to be quite strong. Highly stranded 16-gauge speaker wire, on the other hand, would definitely be too flexible to work with these connectors.
Overall, I am quite fond of these push-in wire connectors, and definitely recommend them. If you regularly use screw-on wire nuts, you might want to try a couple of these Wago connectors to see if they work better for you.
Buy Now(via Amazon)
Buy Now(via Newark)
More Info(via Wago)
Flyer(Flash via Wago)
These wire connectors (773-series) are available via many other electrical suppliers, such as Newark, which is where I purchased mine from.
Have any of you electricians out there used these or similar push-in connectors? What do you think about them?
MT_Noob
Wow, another tool/part I never heard of before, but now I know that I need to try them. Thanks.
Stuart
That has pretty much become my motto. =)
porphyre
Interesting option for higher voltage situations. I much, much, much prefer WAGO’s lever clips. 100% reusable. Great for 12v apps and end of run applications…. Light fixtures and things. I wouldn’t wire up an outlet using them, but they’re fantastic for fixtures.
Stuart
I have a bunch of these too and will start using them later this week. The lever clips work with smaller conductors as well. I believe the push-in Wall Nuts are substantially less expensive, and more aimed at mostly non-removable applications.
fred
Nice to know the option is available.
I’ve never seen these used – but wired (low voltage) quite a few model railroad setups using Fahnestock clips:
http://www.amazon.com/School-Specialty-Science-Fahnestock-Clips/dp/B008C4S31Y/
John Blair
I was an electrician for 5 years and I can tell you from experience that wire nuts when used right are a good reliable system. I can also tell you on some cold mornings, even though I was considerably younger, my hands would cramp up using them. Ideal has a lovely little Romex wire stripper / wing nut tightening device that helps, but only on their winged version.
I do have some concerns with longevity. The most common call I had for electrical repair was the failure of a receptacle that had a wire pop out of a push-in port. This would not only result in a receptacle without power, but everything downstream of it would have the same problem.
Having said all of that, I decided about a year ago once to transition from wire nuts to push-in wall nuts for everything but hard to reach boxes. They are easier on the hands and the work sure looks neater. If you are going to do the same, just make sure to tug on the wires individually to make sure you’ve made a good connection.
Stuart
Improper stripping length seems like a likely cause of failure. Wago is very specific about how long wires must be stripped prior to installation. I agree with you that a quick tug should be done to test connection strength.
fred
We had done quite a number of remodeling jobs that involved stripping out aluminum wiring – or at least replacing wiring devices with ones rated for co/alr use.
I believe that other early fixes included pigtailing with copper – and using wire nuts with anti-corrosive agents.
Aluminum wiring had been implicated in some electrical fires – particularly where “back-wired” devices (e.g. receptacles that used friction clips to make connections) were used. I’m not sure that using side screw terminals would have been any better in these cases . I believe you (Stuart) would know more about this – but I recall that “creep” of the aluminum was cited as the failure mode – loosening connections – adding to connection resistance – resulting in overheating and/or arcing . Aluminum NM conductors had been used in residential construction for a short period of time – when copper was seemingly scarce or very high priced. While aluminum is still used in utility application – I do not believe that its being used anymore for 110/208 in residential application.
Stuart
I didn’t look too thoroughly into the matter, but I have heard about issues with aluminum wiring and backwired devices. I read more about oxidation being a contributing factor to overheating than creep, but creep could very well be a factor.
As far as I am aware, aluminum wiring is not at all used for residential wiring. I haven’t looked into commercial wiring trends at all.
fred
I recall that oxidation – with resultant increase in resistance was one problem – somewhat solved by using some sort of antioxidant goop. The creep issue was more about aluminum wire crunched down under side terminal screws – where creep resulted in loosening of the connection and possibly arcing.
mnoswad1
Fred is right again.
I did this very job…..changing out all receptacles for co/alr rated versions…….in an apartment that was “professionally” remodeled some 5 years earlier and no body bothered to notice that the aluminum wiring.
Yes, did the pigtail with the Nolox anti oxidative, as far as creep…….what your talking about is the different expansion and contraction rates of copper vs aluminum….so as aluminum wire heats up when current passes though it, then cools again, that expansion rate is greater than copper, so the aluminum wire basically loosens itself over time, which can cause an arc and potentially a fire. Plus its very brittle and easily breaks inside the insulation if bent too much.
If your house was built in the mid 1960’s, then you should look into it with diligence.
Steve
the biggest problem for connections is typically cold flow – where the Al deforms under the terminal connection, rendering it a loose connection. Heats up as it is high resistance, and over time oxidizes and fails.
In wire nut joints, from personal experience, the problem is with oxidation, sometimes you open up a joint and there is green death and no Al left on the conductor.
I know that Al terminations on panels often need noalox plus retorquing at a certain point.
Rick
My house has aluminum wire. The selection of CO/ALR switches is quite limited so copper pigtails are a necessity.
It seems that the Wago push wire would be a good splicing solution since it is spring loaded and would maintain a tight connections on the individual wires regardless of their expansion and contraction. Is this not the case? The spec says Copper only. Is that because the won’t work or because the have not been tested and/or certified??
Stuart
I’m sorry, but I simply don’t know how to answer that.
Your best bet is to contact Wago, but my feeling is that they will stick to the copper-only spec. The best that might come out of contacting Wago is that they might have an alternative product or solution for you.
Norm
I use them occasionally. I use primarily stranded wire at my location, so that is why. I do house electrical on the side and I’ve had a few situations that used a 5 device box for switches. So for that I definitely used these wagos as I didn’t want the Neuatal and Power feed coming undone.
Electricguy
Wirenuts are overrated, I’ll take push connectors if the decision were up to me.
Joe W.
I bought some recessed lights a few years back that came with the same style of wire connectors. After using those and (mostly) liking them, I’ve used them on a few other occasions. My one gripe was the difficulty of using stranded wire with them. What I ended up doing after stripping the end of the wire was tinning the end with a bit of solder. I am not a pro, so I don’t know if this meets code or anything, but it made the stranded wire work much better with these connectors.
Jim Searcy
I have been using Wall Nuts for several years. I find them way easier to use. When working with hot wires they are especially nice. Once you put the Wire Nut on the hot wire you can just plug in the next wires, ground first, neutral second and hot last. No need to undo the wirenut and twist wires together with a chance for shorting something out. The wire can roll inside the Wall Nut so when tucking wires back into the box they are not so stiff. They are especially great when you get into the six or eight wire size; small size and easier to shape the wires. Ever run into places where the person before you cut the wire so short that you can’t get a wire nut on it to your satisfaction? Wall Nuts will allow you to bend a “J” in the end of a wire, insert that into the Wall Nut then slip the Wall Nut onto the short wire. This works when nothing else seems to.
In short: I love Wall Nuts.
jeff
these look incredible, i just installed 30+ pot lights with this style connection late last year, and loved them.
Did not know this product existed in this form, I ordered a box 😀
Phil
I’m a fan of the Wall-Nuts, but have started using the Lever-Nuts almost exclusively, especially where stranded wires are involved. No tinning of the wires is needed, and they grip tenaciously. They are easily reused by simply opening the clamp with the lever and extracting the wire.
I find them to be perfect for use inside of machinery as well, vibrations won’t loosen these like wire nuts.
Nick Marques
Ideal has these too – In-Sure Push-In Wire Connectors. I get them from time to time at Home Depot. They are nice although they aren’t nearly as cheap as twist on nuts. Also, you need to know in advance how many wires you’re dealing with, as opposed to twist on that can handle a vast number of combinations of wires.
http://www.idealindustries.com/prodDetail.do?prodId=in-sure&div=0
Stuart
Since so many people mentioned their fondness for the Lever-Nuts, I moved the quick review ahead of schedule – https://toolguyd.com/wago-lever-nuts/ .
joe
I’m not an electrician but I know my way around breakers, GFI plugs, light switches, etc.
The problems I have encountered over the years with electrical connections, is their lack of contact. If I can explain myself right…a wire is rated to handle a certain amount of current due to it’s thickness. When a wire is not making full contact with the contactor, the wire cannot handle the rated current any more. IOW, due to the nature of how these things work, they are not making full contact as a soldered one or even a crimped one.
The times I have seen wires explode/burn is due to not making full contact. I sometimes have to work with live wires, and they spark when you initially touch them together. The science because that is that for a short amount of time, the too wires make little contact reducing their related current capabilities.
Anyways, for small volts I don’t believe it’s much of an issue. I know ceiling fans have three way switches that have push through contacts. Ceiling fluorescent light fixtures have them to (they don’t pull many current and their pull is always the same). Never seen one of those burn. On the other hand, I know some GFI and regular electrical plus have push through options, and I have encountered some where the wired burnt or stopped conducting electricity all together. My opinion is that when there is an over load, the contact is weak in that area that it burns before the breaker has a chance to trip.
So for constants amp draw, I would use them. For a situation that would encounter and over load, I would not. IMO.
Stuart
When connecting a live wire to an inactive wire, the high voltage and current arcs across and ionizes the air as the two wires are brought together. It’s not really a matter of the wires having insufficient contact area.
joe
You are correct about that but the reason mostly wires burn is because they have so little contact that they act like a fuse or a bottle neck.
You can do an experiment if you want….degrade the cable in an area by grinding a little bit of it (if solid) or cutting a few strands (if stranded) and them simulate a high current draw…like a table saw blade getting stuck in a wood knot…or an air compressor having low refrigerant and not starting when the thermostat energizes the contactor.
The section where the wire got cut, will burn before the breaker trips.
Over the years, I have replaced many burnt wires. The reason they burn/explode is due to their connection being compromised. Of course, you also have those that short out too…but that’s another animal. IMO.
Stuart
That is definitely true. Lost or compromised wires = reduced current-carrying ability. A wire’s current-carrying ability is only as high as its thinnest section.
l/dude
Some of the comments/ “advice” referenced in this thread might be deadly. If you don’t understand some basic electrical theory, please, don’t play in this sandbox. I’m not a physics expert, but back in my “Jr. High” days, we learned that electron flow occurred on the outer surface of the conductor, hence, the larger the diameter of the wire (circumference of a #12 conductor is larger in area than a #14, #10 is larger than a #12, etc.), the greater the amp. flow. When connecting two or more wires in a POWER circuit (induction motors, heating elements, etc.) use your lineman’s pliers and twist, twist and then twist some more the circuit wires to achieve the most surface contact between those wires, trim the ends, and then twist the wire nut on to make fast that connection.
In pre-wire nut days, after twisting the conductors together, the electrician would then solder the assembly together, thus continuing the electron flow over the now larger surface area of that connection, and then wrap/insulate that connection with tape (then called friction tape, before 3M, or whoever, developed pvc based insulating tape).
A wire nut (Ideal wing nut, Wago, etc) should never be the sole or primary electrical connection between current carrying conductors. That happens when the “electrician” strips and then holds the stripped wires parallel to each other, while using the wire nut to twist the adjacent wires until the wire nut “feels” as if it can’t be twisted any tighter.
Of course, this isn’t the case for low current draw/low voltage, control circuit connections (HVAC Thermostats, audio circuits, etc.) so you (lazy, semi-) electricians have the benefit of the doubt for that behavior.
All of the Wago and other similar connectors concentrate wire to wire contact to a small area, thus increasing the amperage (electron flow), which leads to higher resistance, which then leads to greater heat, which then leads to circuit breakdown or overheating, which=FIRE, …Did I make my point? There’s a good reason why Electricians have to work for year(s) to learn their trade and then test to prove it. By the way, I’m not a licensed Electrician, just interested in saving my fellow do-it-yourselfers from killing themselves.
Stuart
You are correct about how screw-on wire nuts should only be used on wire pairs that are twisted together.
Push-on wire nuts, as well as the lever-lock ones, do not concentrate wire-to-wire contact to a small area. The spring action actually smushes the wires down into a flat shape, such that there is a lot of contact between the wire and the terminal. There is no reason to believe resistance of the contacts is any higher than that of the wires themselves. Wago is strict about how much wires must be stripped so that sufficient length of the wire is in contact with the terminal connection.
These are UL-rated as being suitable for common wiring tasks, so there’s no reason to believe they wouldn’t be suitable.
I can’t say if these are suitable for use in industrial or special applications power circuitry which might see high amperage power surges, but they are designed to be safe enough for common residential and commercial wiring applications.
Leif Neland
You mention current flow on the surface of the conductor.
This effect is only noticable in very high current situations, like high voltage transmission lines. The overhead cables can have an iron core for strength, covered by an aluminum outher layer for conductivity.
Where the strength is not needed, like in the power plant or the transformer station, the conductor can be hollow, or even consist of two parts like ( ), as the material inside would not carry any current.
It can be explained like this: Imagine the wire consisting of a lot of thin wires. The current flow in the same direction, so the magnetic field of all wires have the same direction, so all wires tend to push at all the others, and the wires would spread out.
For the same reason, the electrons “want” to be as far away from others traveling the same directions, and the current moves toward the outside of the wire.
However, for normal electricians and DIY’ers this have no effect, and you can assume that a wire with double area can carry double current.
Well, almost, a wire with double diameter have double surface area, but four times the crosssection area, so it have relatively smaller area to conduct heat away.
Mike
Skin effect occurs at high FREQUENCY, not at high current.
Why would transmission lines ever use an iron core? It completely negates the reason for using aluminum in the first place – weight.
Marshall E
The skin effect is a function of frequency (not current as someone mentioned), and at 60 Hz the “skin” depth in copper is about 8.5mm. Which means that, no, there is no skin effect in any wire you’re likely to encounter, all the way up to 0000 gauge, where you can still push it to 125 Hz and have 100% skin depth.
Stefan
You are both wrong. The typical WAGO spring clamps indeed use only a small contact area between the wire and the contact rail (there is no wire to wire contact in this kind of clamps) because that is essential for any reliable spring loaded contact. The key word is “gas tight” (which is also the reason for the tight twisting of wires befor applying a wire nut –not the greater contacting surface). The small contact area in a spring clamp results in high pressure and this assures that the contact area won’t corrode.
But I/dude’s conclusion is wrong (while his remark that many advice given here are dangerous is absolutely correct). In the first instance a contact area, no matter how small, has an electric resistance of 0 because it has no length. Of course there is a transition area from the small contact surface to the full cross section of the wire but this is very small and the current (as well as the heat that is locally produced) distributes well into the wire and the contact rail.
What makes spring loaded clamps superior is that they hold the pressure no matter how much the wire expands, contracts, creeps or vibrates. That’s why they are used in applications that are much more demanding than your residential wiring (trains, tunneling machines, heavy industry) -albeit in other sizes an form factors, but the basic technique is always the same.
Btw.: I/dude’s idea that electron flow occurred on the outer surface of the conductor is also wrong. There is something called “skin effect” but that has no impact on your residential 60Hz wiring.
Tomonthebeach
I first used these when I discovered an open connection box in the attic that had so many wire nuts in it that the electrician (?) did not even try to replace the cover. These doohickies enabled connecting all the wires with less clutter, so I could re-attach to cover. I have also started using Scotchlok butt connectors since relocating to Florida as they contain conductive goo to help keep out moisture. They too take up less space than wire nuts. In either case, one nice feature of both connectors is that you can see that the wires are seated – something impossible with wire nuts.
Fred Wamsley
Everyone looking at contact area and raising the issue of current capacity is asking the right question.
The answer has been reached, by experiment.
Over on electriciantalk.com, some people have run space heaters through WAGO connectors and measured the temperature of the connector. They remain cool.
The next question is whether they’ll be the weak link in an overload, before the circuit breaker responds. Here’s the answer to that question:
http://www.wago.us/resources/?mp4=/media/us/collection/videos/222_extreme.mp4&ogg=/media/us/collection/videos/222_extreme.ogv&webm=/media/us/collection/videos/222_extreme.webm&controls=1&autoplay=1&poster=/media/us/collection/videos/222_extreme.jpg
Notice that the connector fails without arcing.
The next question after that is whether they’ll be like stab locks and work loose after years. That’s harder to test.
Stuart
Thanks for sharing that video, it shows a pretty impressive demonstration of how robust these connectors really are!
J Freeman
I use these in my attic to connect #14 Romex in multiple j-boxes for multiple connections to my multiple dim-able LED can lights. Every room in the house now has a minimum of three dim-able LED can lights each (45 total). These connectors make installation a breeze. Everything fits nicely into the j-boxes. My 1956 Southern California 3 bedroom 1325 sq ft house is now incandescent free. My electrical bill on average hovers around $25.00 a month. Love them…
Edward Norton
I am an electrician of 50+ years & will tell you that the push on connectors are the beat thing to come along since the wheel! I have been using them for the past 5 years with no problems and or failures. On average they save me at least 2 hours per day, not to mention that they are a lot easier on the fingers & hands. They also make connecting multiple wires in one device box a breeze as well as they take up a whole lot less room. Once connected they are easily maneuvered and compressed into the box.
Rick
Has anyone have a problem with a code Inspector using these connections?
Stuart
These are UL-listed, and when I spoke to Wago in the past they said they take steps to ensure wiring products marketed to the US meet code requirements.
That said, different inspectors might use their discretion – you could try contacting them ahead of time to see their take on these. Other brands also market push-in connectors to the US market.
richard grzych
thanks for the info