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From: piglet <erichpwagner@hotmail.com>
Newsgroups: sci.electronics.design
Subject: Re: Minimum clearance for 230V AC.
Date: Thu, 3 Oct 2024 13:16:21 -0000 (UTC)
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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.
> 
> 
> 

I’d also want to consider if the pcb tracks are naked or covered with
solder mask or conformal coating .

-- 
piglet