[James Newton]

https://youtu.be/TZ01mezCWuE

Not my video but I crimp every multi core wire because that is the only way to make sure you get good and reliable connections in screw terminals. Very common and I think (at least in Europe) it is compulsory to use those in industrial applications. There are different crimp tools, the one in this video is just one of the many types.

This is REALLY good advice. I use a different type of crip connection (one intended for a screw) only because I have a ton of them, but then I cut off the end and just use the part crimped to the wire. Other options which are NOT as good, but can work:
- A VERY quick drop of solder on the end of the wire. This is usually a really BAD idea because the solder will "wick" up the wire and destroy it's ability to flex in the part outside the terminal block. But, if you do it really quick with a really hot iron, you can avoid the wicking and still have a solid joint at the end. The other reason this is bad is that the soldered end will deform in the terminal block clamp, and loosen over time. You can avoid that issue by repeatedly re-tightening the screw until the solder has completely filled the terminal block clamp area. In the end, if it's done right, it works very well and is very reliable. It's just difficult to do right, and so not recommended.

- Really good quality terminal blocks with very carefully stripped wire. Again, works fine if it's done exactly right. What happens here is that the terminal block clamp area is corroded, dirty, or just not good quality or the wire is corroded, dirty, or too small, and so the contact has a high resistance. The other thing that goes wrong is that when you strip the wire, you nick one or more of the outside strands, and then as the wire is flexed that nick slowly breaks, creating a sharp edge that digs into the next strand and eventually the entire wire cracks off.

So I mention those two possibilities just to point out why crimping something on works better. It avoids stiffening the rest of the wire like the solder does, and the ferrule won't compress like solder. If you put the ferrule on with a bit of the insulation in one end, you are crimping over the start of the strip, so any nicks in the wire are held together and wont work loose. You can still have issues with corroded or dirty terminal blocks, but because the ferrule won't deform, it actually has a higher pressure at the points where it makes contact. It makes contact over less area, but better contact in the 2 to 4 places where it does touch. And that is actually better. In those places, there is a better chance of it cutting through the corrosion or dirt.

And that turned into a book. Sorry. Hope it helps explain WHY crimping a ferrule on is best.