Testing Different Wire Connections

All of these connections are made with bare 14AWG copper wire, steel-wooled in between each use and not contacted with fingers. Each test is made at 10A from a low voltage transformer adjusted by a variac, and the voltage drop measured with a Keysight 34450A. I am not very smart so I did not take a control test of just a straight piece of unspliced wire but if I do that I'll put it here later.

Wago 222:
Clean straight wires inserted. Voltage drop is unsurprisingly the highest of them all, but still not bad. Slightly under .5 milliohms. Very usable despite being the worst.

Wirenut without pretwist:
I always pretwist, but apparently it's not horrible if you don't. Better than Wagos, ~.35 milliohms.

Wirenut with pretwist:
Definitely made a noticeable improvement, down to around .29 milliohms.

Twisted+welded:
These wires were twisted together and then the tip was melted into a copper blob with a carbon arc. Surprisingly this was only marginally better than the pretwisted wirenut, maybe the annealing/heat has something to do with it. This was just something weird I wanted to try. ~.27 milliohms.

Twisted+soldered:
Unsurprisingly this performed the best, only .12 milliohms. I used lead-free solder, however leaded would probably perform very similarly.

Are Wagos technically worse? Yeah, but not by any sort of considerable margin. I personally use wirenuts (pretwisted) almost exclusively just cause that's what cheap, and I will probably continue doing so, but Wagos definitely have plenty of uses. If you are doing these kinds of connections for a living then it's a lot easier with Wagos. I used to think that pretwisting made all the difference, but I guess that is not so much the case. Maybe later I will also test the European-style terminal blocks, or if I stumble across a Wago 221 I'll see if they are any different from the 222s.