Using FR4 with 240V AC Mains

Yes.

As far as I remember, UL specifies 8mm distance between tracks on the same side. If the 8mm are not achievable, then you can mill a through-groove out of the material.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Hi Rene,

Thanks for the reply.

That's going to be a problem. several of the components don't have that sort of spacing. I've seen a lot of equipment such as TVs etc where that hasn't been done.

Do you have any idea where I can get the UL spec?

-Mike

Thanks.

-Mike

If you're in Australia ( as it seems ) you'll actually want the IEC spec. UL is for the USA only.

It's 6mm IIRC between live parts and *secondary* parts btw. You don't need 6mm between live and neutral.

Graham

Hi Graham,

That makes sense. I purchased AS/NZS 3820:1998 that appeared to be what I want but it was a waste of time. This just lists safety issues that are common sense.

Do you know which standard I need, or how I can find it?

Also, this device may end up being used in the USA so I do need to find the UL spec as well.

-Mike

The 2 IEC safety standards I'm familiar with are IEC 60065 ( consumer audio, video and the like ) and IEC 60950 ( IT equipment ). UL's UL 1950 is now very similar to IEC 60950 btw.

You'll need to consider EMC issues from the compliance aspect too of course.

Graham

Thanks. Plugging those numbers into Google gave me some good links.

I have a bit of experience with EMC. I'm concerned about the trace length of the ground from the junction of C3 and C4 and was hoping someone with experience with mains would know if it is worth a prototype or I need to do the layout again.

Anyway, I'll get the specs and see what I need to change for safety and go from there.

-Mike

I'd keep all the mains filtering close to the inlet personally.

C3 and C4 should be *Y* types ( not X ) btw.

Graham

I don't want to change the size of the PCB or position of the IEC sockets if I can help it. If it's ok to run actives over neutrals and earths anywhere then I have more options.

Ah, yes. Copy & Paste error. :-)

-Mike

As others have responded there is no problem in running 240V (presume that is 339V) between top and bottom layers of (1.6mm) FR4. However looking at your layout there are serious safety problems if this is to be a commercial product for sale in Europe - dunno offhand aout the USA. There is a 'regulation' called the Low Voltage Directive (LVD) which demands that products be electrically 'safe'. The keywords you are looking for are and need to understand to start with include 'creepage and clearance', 'basic', 'reinforced', and 'supplementary insulation', and 'proof tracking index'.

As it is your design would be considered unsafe.

Can you point to the bit you consider unsafe ?

I didn't spot anything iffy on a casual glance.

Graham

Thanks for your reply. I'll do some searching on the keywords you mentioned. Can you offer any suggestions as to where the problems lie or how to fix them?

-Mike

Which *bit* do I consider unsafe?

By a cursory glance

1.live to neutral creepage & clearances in many places

2.phase (live and/or neutral) to earth creepage & clearances almost everywhere

3.X2 caps connected between phase (live and/or neutral) and earth (I cannot read the circuit diag well enough to see their value but can make out they are X2 rated)

I do of course assume that phase to phase to earth integrity is not to be enhanced (slotting/routing, potting, conformal whatever for wherever). Even were this so (and it came up to spec.) the X2 caps would open the door to prosecution if there was a problem and at the least a total product recall if no bodily harm had resulted.

Is this for europe or the USA or wherever?

What distance do you reckon is required then ?

Previously covered. They should indeed be Y types. Not a pcb layout issue though.

Graham

At this stage it's for Australia. However, there is a chance we could sell in the US and a small chance of sale in Europe.

This is the first time I have done mains design and would like to do it right anyway.

I have not found any specific information so far using the keywords you gave me, but I'm still following the links.

The LVD documents I downloaded only talk about documentation requirements.

-Mike

LVD is simply the 'law'. The standards required will be the IEC ones ( actually ENs in Europe but they are essentially the same thing ).

E.g. I refer to BSEN 60065 ( the 'British Standard' ) for products I design - equivalent to IEC 60065.

In Australia you have your own standards but again these are derived from IEC.

Only the USA is different ( as ever ) but even here the more recent UL standards have adopted most of what's in the the IEC equivalent.

Graham

Yes the caps have been previously covered.

Basic insulation for 230V mains is a minimum 2.5mm creepage, 2.0mm clearance but you must fully understand what is meant by 'basic insulation' . 'Basic insulation' here does not mean the 'minimum acceptable insulation'

Best to start with EN60950