This is the safety requirement that our company adheres to, and I hope that it will be helpful to you! . "Safety certification of the basic requirements of the printed circuit board creepage distance and electrical clearance: when 130V < working voltage ≤ 250V, no anti-dust accumulation ability conditions, the insulation between different phases electrical clearance ≥ 2.5mm, creepage distance ≥ 3.2mm, basic insulation (between strong and weak) electrical clearance ≥ 3.0mm, creepage distance ≥ 4.0mm, the width of the slot should be greater than 1.0mm, the length of the slot should ensure that the creepage distance meets the requirements, in order to make the mass production of PCB can meet the above requirements, PCB in the design of the above safety dimensions must be increased by 0.2mm, slotting width in the conditions allow the recommendation of 1.5mm or more."