Electronic – Mains voltage PCB design


I am trying to design a PCB with AC mains which is going to be controlled using relays to turn on fans and heater. I have never designed PCB for AC. What should I look out for and what should I be doing when designing for it?

Best Answer

When working with line voltage there's some key points that come up:

  • Insulation / isolation between mains and low-voltage
  • Creepage / clearance on the board
  • Fire retardant materials (that's where the 'FR' in FR2 comes from)
  • Safety approved components

The main standards for the board that apply are:

  • IPC-2221A, "Generic Standard on Printed Board Circuit"
  • IEC-60950-1 (EU and many others)
  • UL 60950-1 (USA, generally harmonizes with IEC-60950-1)

Some more info:


And, there is a new standard replacing IEC-60950-1, which uses hazards-based methodology, called IEC-62368-1. This takes effect on Dec. 20 2020.

More here: https://www.cui.com/blog/the-latest-on-iec-62368-1