230V Safety & EMC Notes

2. Power & Electrical Safety Requirements (REQ-SAFE)

ID	Requirement Description	Target / Parameter	Verification Method	KiCad / DRC Link
REQ-SAFE-01	Direct universal AC mains input converted on-board to isolated low-voltage DC.	230V AC 50Hz input to isolated 5V/3.3V output	Load regulation & thermal check	`hardware/sheet_power.kicad_sch`
REQ-SAFE-02	Over-current and transient surge protection on the AC mains entry.	1A slow-blow PCB fuse + 10D471K MOV	Visual BOM & schematic ERC	`hardware/sheet_power.kicad_sch`
REQ-SAFE-03	Reinforced creepage and clearance between 230V AC primary and 3.3V/5V secondary circuits.	>= 5.0 mm clearance + 1.5 mm milled isolation slot	KiCad DRC (`Mains_HV` custom rule)	`hardware/step-and-study-hub.kicad_dru`
REQ-SAFE-04	Fully enclosed touch-safe housing suitable for a children's bedroom.	3D-printed enclosure with strain-relief cable exits	Mechanical fit & STEP inspection	`enclosure/case_v1.step`

ID	Requirement Description	Target / Parameter	Verification Method	KiCad / PCB Link
REQ-EMC-01	Conducted EMI suppression at the 230V AC mains input stage.	X2 safety capacitor + common-mode choke before AC-DC module	Schematic review & line noise check	`hardware/sheet_power.kicad_sch`
REQ-EMC-02	Uninterrupted low-impedance ground return path on the low-voltage section.	Solid `B.Cu` ground pour with edge stitching vias	PCB layout inspection	`hardware/step-and-study-hub.kicad_pcb`
REQ-EMC-03	Local power-supply decoupling on all active ICs and wireless modules.	100 nF + 10 uF ceramic capacitors within 3 mm of VDD pins	PCB layout inspection	`hardware/step-and-study-hub.kicad_pcb`