There are various reasons why wire nuts can stop working, some of them more obvious than others. So if you’re in the middle of a project and your wire nuts aren’t working, or if a wire nut stopped working after a period of time, here are some things you can do about it.
Let’s get a disclaimer out of the way. Some of this will seem obvious to some of you. Maybe all of it. If it is, I’m happy for you. You’re not the intended audience.
For others, all of this is new information. Before you scroll down to leave a comment that this is all common sense, remember nobody was born knowing this stuff. And not everyone had someone to teach them. For this reason, I disabled comments on this post.
Wire nut doesn’t work
Usually when a wire nut doesn’t work, or a wire nut stops working, it’s because it wasn’t installed correctly. No judgment here. Sometimes these come with instructions and sometimes they come in a plastic bag with little more than a UPC.
Let’s talk about how to fix it and an alternative you can use when that’s not practical.
The first thing to check is if a wire nut doesn’t work is to make sure it has its metal insert. Wire nuts have a threaded metal insert that looks like a conical spring. Without that insert, the wire nut will spin far too freely on the wires, it may not stay on, probably won’t feel quite right, and it won’t do anything to improve conductivity. The wire nut should give some resistance when you twist it on, and without that insert, it won’t do anything.
If the problem isn’t the metal insert, it’s probably one of four other common mistakes. You can correct all of them, at varying degrees of difficulty or cost.
How to correctly use a wire nut
There are some common mistakes people make when installing wire nuts. Most of them are easy to correct. These problems can lead to a connection not working, but they also lead to poor conductivity, which leads to excess heat. The excess heat from that resistance can compound the other problems over time. This can include bulbs burning out prematurely, flickering lights, or eventually, the fixture not working at all.
The first mistake is reusing them. They are really supposed to be a single use item. You can get away with it sometimes. A majority of homeowners have. Sometimes just using a new wire nut fixes the problem.
But I do recommend checking for other problems and correcting those while you’re at it.
The second mistake is not cutting back the wires. When you install a wire nut, it cuts grooves into the copper wire. When you go back and twist a new wire nut back on, these grooves can prevent good electrical contact. With less surface area, it’s harder to get a good connection.
When you make a change to the connection, you are supposed to cut off the exposed wire and strip back about a quarter inch of fresh new wire. Be sure to use this trick to ensure you don’t damage the wire when stripping it.
That’s one of the reasons installers leave plenty of slack in electrical boxes. Of course, not everyone leaves enough slack, and if your house is several decades old, and everyone’s been following rules, eventually you run out of slack. There is a solution for that. More on that near the end.
Mistakes in twisting the wires
The third mistake people make is the way they twist the wires together. Sometimes they don’t twist the wires at all. If you just spin the wire nut onto two wires in parallel, you get a poor mechanical connection and a less than optimal electrical connection at the very least. You’re supposed to twist the wires together with a pair of pliers, then put the wire nut in place. This way, the wire nut is supplementing an already solid mechanical and electrical connection and providing insulation, rather than relying on the metal insert for all of the mechanical strength and full responsibility for the electrical connection.
A fourth mistake is using the wrong size. They come in different sizes depending on the number of wires you are connecting and how many wires you are connecting. There is some overlap in capacity, so you can go up or down one size and usually get away with it. When a wire nut doesn’t feel like it’s fitting right, that’s a good sign you need a different size. For household use, a yellow wire nut is usually a pretty good size for connecting two or three wires.
An easier alternative to wire nuts
If you don’t have enough slack left in the wire in your box, or if you just need something that is easier to install and reusable, there is an alternative. These alternative connectors are called lever nuts, or sometimes called Wago nuts, after the name of the company who invented them. Genuine Wago connectors are very much available, but less expensive knockoffs are also widely available online.
The downside to lever nuts is they cost more and they aren’t as readily available. You can get wire nuts at the nearest hardware or home improvement store, and potentially even a discount store. You may not be able to get lever nuts except at an electrical supply store, or by ordering online. They also cost a dollar or two a piece, as opposed to a few cents a piece when it comes to wire nuts.
For best results, prep the wires before use, but if you don’t have any choice but to swap a lever nut in while leaving the wires as is, it’s more likely to work.
It’s up to you to decide if it’s worth it, but being able to make the connection quickly and reliably without special tools and being able to reuse the connector and not having to worry about wire length ever again is probably a good trade-off for most homeowners. Especially if you expect to have to change the fixture again.