Re: Minimum clearance for 230V AC.

On 2024-10-03 20:03, john larkin wrote:

On Thu, 3 Oct 2024 22:05:37 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
 

On 3/10/2024 8:11 pm, Pimpom wrote:

What's the minimum surface clearance you consider adequate for 230VAC,
on FR4 without slots or added creepage? Forget about IPC-2221 unless you
base your layout strictly on it.
>
Personally, I try to maintain 3mm edge-to-edge between tracks and pads,
more if space permits. What do you think?

>
The distance along a surface is called creepage in the standards.
>
The required distance depends on whether the insulation is supposed to
be single insulation (functional, basic or supplementary) or double
insulation (reinforced insulation).
>
Basically, if the insulation failing ought not to kill someone because
the part that would become live is either protectively earthed or
separated by supplementary insulation from the user, then a smaller
creepage is allowable.
>
If the insulation failing could immediately give someone a shock because
there is no protective earthing or supplementary insulation, then a
larger creepage distance is required.
>
The exact distances required in different standards tend to be
different, though I think a lot of different products that used to be
subject to different standards have recently been grouped into one set
of standards, IEC62368-1.
>
There are some tables here:
https://www.powerctc.com/en/node/4757
>
I think you are going to come up with something like 2.5mm for basic
insulation and 5mm for reinforced, but you should check carefully what
the standards say, and for some classes of equipment it can be much
more, like 6mm or 8mm.
>

  What about voltage clearances for inner-layer traces on a multilayer
board? Same layer and between layers?
  

See e.g. the IPC 2221 standard, clearance chapter 6.3 and table 6.1,
at https://www-eng.lbl.gov/~shuman/NEXT/CURRENT_DESIGN/TP/MATERIALS/IPC-2221A(L).pdf
or see e.g. https://philipmcgaw.com/creepage-and-clearance/
There are also a lot of EU and UK standards that have detailed descriptions (and are mandatory for anything sold in the EU).
Even hobby magazines carried tables for some time, but removed them for juridical reasons...
Arie