There are wire nuts and then there are electrical spring connectors.
Spring connectors have a live memory spring that expands and contracts with the bared wires held by the spring caused from any expansion of the conductors due to the connected load. These are the type of connectors that are spec for power wiring on mid to large size commercial/industrial building projects.
Examples,
3M Scotchlok insulated Electrical Spring Connector.
https://www.egr.msu.edu/eceshop/Par...nsulated electrical spring wire connector.pdf
Ideal 30-641 Twister Winged Wire Connector With Square Spring; 22 - 8 AWG, 3/22 AWG Min, 3/10 AWG MAX, Tan, 500/BG - Crescent Electric Supply Company
Buchanan / Ideal B2-B I B-CAP Red Twist On Wire Connectors; Box of 500 - Crescent Electric Supply Company
Ideal B1-1 | Electrical Wire Connectors
I would run away from stab in pressure clip connectors. I have seen to many of them used in residential grade receptacles of the past that failed.
Problem with connectors where the bared solid wire is inserted into a lug and a screw is then tightened down securing the solid wire connection is over time, with varying connected load current traveling through the connector, the connection can become loose. This type of connector needs to be re-torqued for tightness as time passes, but the manufactures fails to say so in their lit.
In my area there are residential house wiremen that still twist, solder, and tape, the jointed connections. The equipment grounding conductors are twisted, soldered, and then a cheapo UL listed ground crimp barrel is crimped over the soldered connection to meet NEC code.
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Stranded is forbidden around here for fixed/in wall installation. It is unreliable, especially at connections.
To make a reliable connection to stranded wire in a screw terminal, you'll need a crimp-on endcap. Without it, the thing always seem to end up loosening if there is vibration or thermal cycling, or it ends up having just a few strands making contact, which can cause a fire if a large current goes through.
Humidity and various airborne contaminants will enter the wire at the end and corrode the surface. Not a problem with solid core, but with stranded there is a lot more surface area to corrode.
ABout wire nuts, they seem to be forbidden around here. No idea why.
Those screw terminals are crap (like most screw terminals...), slow to install...
Reliable connection is either weld, solder, or have a spring that applies a constant (large) amount of force. Screws don't do that, so thermal cycling can loosen them.
For solid core house wiring, this is the stuff everyone uses. They're very easy and quick to use (strip and insert), the wire is free to rotate a bit inside so you can push them into the junction box afterwards more easily, there is no exposed metal (except the little hole for the multimeter probe tip), and they're extremely reliable, the spring is very tough.
For stranded or solid, those are the best , a bit expensive, but very quick to install and remove, works wih stranded too, and the spring applies a truly huge amount of force... they're great to have on the bench for electronics too, because of the easy quick open/close lever, much better than alligator clips !
I have never seen a wire nut in the wild so I suppose that they are illegal in Germany and the UK.
In 40 years I have never had any problems with screw terminals.
Only thing is that they are not really re-usable because the screw head is a little bigger than the hole it sits in. If you redo them more than 2 or 3 times the plastic won't hold the screw tight anymore.
But then they are dirt cheap.
I wired all my house with the tiny Wago 2273 for solid core wires, and some 222 (the ones with clamps) when stranded wires were involved (ie, light fixtures). It's really easy, saves time, and the tiny ones fit in very little spaces. Those things are great !
There are some (not so cheap) cheap copies, I wouldn't trust them.
Recently I installed some IKEA light fixtures which came with spring loaded terminals, a bit like the wago 222 but without the lever. After assembling everything, I switch on the light... nothing happens. So I disassemble it, and see the wires had come off. These things really don't have any strength, the spring is too weak. So now everytime I install something that comes with this kind of connector, I throw it away and put some 222 instead...
Back to diyaudio, I'm looking for something like the wago, but PCB-mount. I hate PCB screw terminals. Not screwed tight enough, the wire comes off ; and when trying to screw tight, sometimes the pad comes off, or it's the whole thing that breaks away from the PCB. I've seen some PCBs with spring wire clamps, but they were quite flimsy and to remove the wire, you had to apply a lot of force on a really tiny crappy plastic button with a screwdriver... while being very careful not to break the thing, or have the screwdriver slip and destroy some SMDs or tracks...
There are some (not so cheap) cheap copies, I wouldn't trust them.
Recently I installed some IKEA light fixtures which came with spring loaded terminals, a bit like the wago 222 but without the lever. After assembling everything, I switch on the light... nothing happens. So I disassemble it, and see the wires had come off. These things really don't have any strength, the spring is too weak. So now everytime I install something that comes with this kind of connector, I throw it away and put some 222 instead...
Back to diyaudio, I'm looking for something like the wago, but PCB-mount. I hate PCB screw terminals. Not screwed tight enough, the wire comes off ; and when trying to screw tight, sometimes the pad comes off, or it's the whole thing that breaks away from the PCB. I've seen some PCBs with spring wire clamps, but they were quite flimsy and to remove the wire, you had to apply a lot of force on a really tiny crappy plastic button with a screwdriver... while being very careful not to break the thing, or have the screwdriver slip and destroy some SMDs or tracks...
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