There are a lot of laws and regulations about electrical installations.
In many regions, doing it legally requires lots of courses and certificates. When you have invested all the time and money into getting said certificates, which is sometimes multiple years full time, you typically want to become a full time electrician to pay back the time+money investment.
That means that 'I just do electrics on the side' is becoming a thing of the past - at least in places with strict certification requirements.
Obviously in most parts of the world, there is no electrical police who will raid your home and look for evidence of wiring done without the correct certifications.
Therefore, lots of people DIY stuff illegally...
If you choose this route, understand that:
* The main cause of injury/death caused by electrics is fires. Fires are normally caused by improper fuses (a fuse/breaker should always be the lowest rating of any device/cable/connector downstream of it, unless that device has its own fuse), or badly made joints. Do joints properly with wago blocks or by tightening screw terminals very tight.
* The 'obvious' risk from electrics of electrocution is reduced to almost zero by installing a whole-house RCD/GFCI device. I wouldn't want to live in a house without one. And turn the power off before doing electrical work.
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.
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"
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.
In many regions, doing it legally requires lots of courses and certificates. When you have invested all the time and money into getting said certificates, which is sometimes multiple years full time, you typically want to become a full time electrician to pay back the time+money investment.
That means that 'I just do electrics on the side' is becoming a thing of the past - at least in places with strict certification requirements.