PCB space between traces

[jimg]

How much space needs to be between PCB traces that will carry 120V AC?
Specifically, in this picture, how much space between the pads? The current should be less than 16ma.

 

[Marks256]

What does the big oval thing represent?

 

[mramos1]

What does the big oval thing represent?

Probably where to solder one side of that big power cord?

 

[jimg]

Yep. Just to represent 120V AC. (It's actually a little less than 200 mils.)

 

[Marks256]

Yeah...

 

[jimg]

So, no words of wisdom for a dumb newbie hobbyist?

 

[Nigel Goodwin]

So, no words of wisdom for a dumb newbie hobbyist?

I would merely state the obvious! - it's NOT a good idea to put the components side by side like that, as you're reducing the gap between traces. There may be some formula to work it out?, but common sense says the further the better!.

 

[picasm]

There may be a theoretical minimum clearance for ideal conditions. But you should allow safe clearance that meets regulations such as the General Low Voltage Directive (LVD).
There are some links to pages giving more info and calculations at:
https://www.epanorama.net/links/safety.html

 

[philba]

I would think that you need to consider the dielectric strength of air which is given in several refs as 20-75 kV/inch or 20-75 V/mil. Based on this, 100 mil spacing should be sufficient (2kV). What isn't clear to me is the effect of humidity on breakdown voltage.

 

[Hero999]

Interestingly breakdown voltage increases with humidity, but you need to leave a bigger gap because condensation on the surface of the insulator will increase tracking.

 

[jimg]

Thank you all. So stagger them to increase the gap, and maybe putting a glop of silicon caulk to stop condensation/humidity ought to be sufficient.