And many places in the US allow homeowners to do work that nobody else can do without certification - sometimes even skipping the permitting.

It is still worthwhile to understand what you're doing, and how the breakers/GFCI/Arc fault will save your ass - and why they are NOT the same thing!

But not too tight, or the strands may break.

I have seen lots of near-fires/melted things from under-tightening, but I have never seen a single near-fire from overtightening. I suspect it's a myth - I don't think you could overtighten any connector sufficiently to make it be a fire risk without the screw shearing first.

I'd be interested to see tests demonstrating otherwise though.

Obviously if you are doing it to the standards, you crimp the wire first and use a torque screwdriver to tighten to the exact correct torque.

> I have seen lots of near-fires/melted things from under-tightening, but I have never seen a single near-fire from overtightening.

That depends what you see as near-fire ;) I recently helped out a friend whose lights had issues after she installed a more powerful fixture, turns out that the person installing it overtorqued the wire in the switch so much it nearly sheared off probably already during installation, and came completely apart when I took the switch out of the wall.

Better be safe than sorry and use Wago clips.

In most cases you use solid wire. In case you use stranded you should crimp the ends anyway, and crimping does exactly opposite, crushes wires so tightly they form practically solid metal.

Strands only break when wire moves and that would be the fault of bad stress relief, not "screwing it too hard"

Wago blocks are wonderful, and I hope I'll ever twist two wires together under a wire nut ever again.

Are you sure that's "illegal" or just "illegal to take money for it" ? Here (Poland) you can do it just fine on your own stuff as long as you don't pretend to be electrician and sell your service, with caveats (only touching anything after power company stuff IIRC)

In much of the US, you are allowed to do any work that you want to on your own property, though if a professional would be required to get permits and inspections to do the same work then you usually still have to get those permits/inspections.