When designing a PCB for a low-voltage circuit that connects to the mains, how much clearance must be used between the mains or primary side and the low-voltage or secondary side of the circuit? This may sound like a trivial question but, unfortunately, it isn't. A typical example would be a mains-switching relay controlled by a microcontroller.
PCB clearance and creepage

In the first part of this series, we concluded that IEC 62368 is the standard that applies to our situation. The second part gave us the criteria that determine the clearance and creepage distances to use in our PCB design. In part 3, the last part, we finally get to the numbers.


Resources & Links

- IEC 62368-1 draft 4b
- IEC 62368-2 draft 4a
- Clearance & Creepage Part 1
- Clearance & Creepage Part 2
- Clearance & Creepage Part 3