I wouldn't consider mains electric circuits as "simple". It is more an advanced area in which special precautions must be considered to prevent serious risk of injury, death, or fire.
"Simple" circuits are the ones used in the Arduino starter kits, where the only way it's going to kill you is if you try to eat it, and an electrical fire is not impossible, but improbable. You are more likely to release small clouds of noxious smoke.