I want to have a 230V side on a pcb, not sure how to do it safely

I have made two different pcb layouts that are basically a flip-flop circuit controlling a relay to switch 230V.
Is it possible to get some expert advice about my design?
If so, what the best (most helpful) way I should upload my pcb design?

If you upload the sketch as an fzz file (7th icon from the left on the reply tool bar), that will give us the entire design including the pcb to comment on.


board 2.fzz (57.0 KB)
board 1.fzz (55.9 KB)

I have made all of the trace 48mil, and have double layered the 240V connections and I have kept as much 240V trace separation as possible.
I tried the “copper fill” fill option but gaps to the traces looked very small and I couldn’t figure out how to increase the clearances.
Any suggestions appreciated.

I don’t often make pcbs so hopefully some of our folks that do will comment about the copper fill settings. That said it looks pretty good, you have realized that fuses are a necessity, and after that you need to check the trace width and copper weight will support the current you expect (and at least briefly, til the fuse blows the current you don’t expect in the case of a short :slight_smile: ) without excessive resistive heating in the traces but I don’t expect that to be much of a problem here as you look to be running less than 2 amps from the fuse values and the trace runs are rather short.


Hi Peter, thanks for the reply.

The trace will be about 1 ozCU, so at 3 amps and less than 50mm long I should need about 50mil traces. I have used two 48mil (one top and one bottom) traces per 230V connection so it “should” be enough. However, I would rather have a wider trace on one side of the board and have it surrounded by some Copper Fill which I want to connect to a ground point.

I have seen some talk about increasing the max trace width (currently 48mil) but I can’t find a way to do this. Also, as far as I can find out it is a good idea to have a minimum of 3mm clearance between a Copper Fill and high current traces. I have seen some discussion about changing the Copper Fill clearances in Fritzing but unfortunately nothing definitive.

Does anyone know of a way to increase the trace width and/or increase the Copper Fill to trace separation?


I’n no 240V expert but usually you put high voltages in a corner with large gaps to everything and isolation slots. And then use opto isolaters between the low and high voltages so that they are never in direct contact.

Width is in inspector.
Gnd Fill is in Routing.

EEVblog talks a lot about 240V isolation in products. Too many vids to find something at the moment.

Thanks for the info Old_Grey
I now see how people are getting 128mil trace widths… I had hunted through the menus and never noticed the zero in the Inspector>Width dropdown list!

Thanks again.