Clearance for 230V design

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#1
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Hi all,

Doing a AVR design that involves 230V. What is the required PCB signal width and clearance between signals to pass CE compliance?

Kind regards
Bjorn

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The high voltage from low voltage tracks clearance depends on the product type (consumer, automation, military, aerospace ....). It also depends on the altitude that product functions.

The track width depends on the current flow.

EDIT:
There is a standard that defines thing like that. Just google for it.

Michael.

User of:
IAR Embedded Workbench C/C++ Compiler
Altium Designer

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6mm or so IIRC, but if you open up a cheap switching phone charger or laptop power supply, they don't come even near that.

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Thanks for your replies.

icarus1 wrote:

There is a standard that defines thing like that. Just google for it.

I've done that, found several pages. The problem is that no Google page seem to agree with the other.

/Bjorn

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Well it depends on many things, eg :
* Does the apparaturs depend on Earthing (PE)?
* Does it include a fuse ? Sometimes you can decrease distances beyond a fuse but not in all cases.
* Application where it is used
* Are there user-accessable metal parts ?

IIRC for a product I designed 10 years ago it was described in the EN60335 (Check Semko if youre in Sweden). Some distances for 2 products I designed :
Product 1)
Powering from L,N and PE class I product
Distance between L and N 2mm
Distance between L/N and PE 3mm
Distance between L/N and user-accessable voltage 3mm

Product 2)
Powering from L and N, no PE, class II product
Distance between L and N 2mm
Distance between L/N and user-accessable voltage 8mm

(No guarantee on these values - they came from a rather far part of my memory)

Besides this there are much more things to take care of, it would be usefull to do a quick-scan on a device you are (going to) design. This quick-scan gives you probably a list of things you have to change or take care of.

If possible, buy an AC/DC power adapter than the regulations are much easier to follow.

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Dear Paddy,

Thank you for your extensive reply! I've already taken into account your last idea to buy a finished AD/DC power supply. But my power supply does not have a fuse, so the 230V goes into my PCB, through the fuse and the onwards to the power supply.

The only thing that is connected to PE is the power supply. The entire casing is plastic. So I'm somewhat confused if my product is Class I or II. Any wisedom to share regarding class?

Kind regards
Bjorn

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At least you can use multiple of 1 mil for your voltaje...
you need 230v clearance so use at leaset 23mil clearance.
and for your current you can use multipe of 1mil for 100 milliamps.
if you need 1A you should use at leaset 10mil track withd....

I love Digital
and you who involved in it!

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Quote:
So I'm somewhat confused if my product is Class I or II. Any wisedom to share regarding class?

IIRC it was something like :
Class 1 = Supplied from L, N and PE in which the safety depends of PE (e.g. desk-drilling machine)
Class 2 = Supplied from L, N and the protection of the device is not dependent of PE terminal (e.g. television - there is no PE on the powerplug) also called double isolated with a symbol of 2 squares in each other.

You say your enclosure is fully plastic, but I assume there are also user-accessable electric components like ON/OFF switch, display, keyboard, connectors and that kind of stuff ?

The Low-voltage directive gives you more information on this.

See http://www.intertek-etlsemko.com... for information on how to come to a certification.
(Semko is not the only company who does this AFAIK)

Once you know what standards you have to comply to, order the standards (costs money) and study them. They will provide you with the information you need. Be prepared that once you bought a standard, this could link to another standard which again costs you money.

If you want you can provide more information on your product (where it is used, description, schematics and chosen components etc) on this forum or PM.

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Paddy:
Powering from L and N, no PE, class II product
Distance between L and N 2mm
Distance between L/N and user-accessable voltage 8mm

It is not 3mm for classe II ?
Thierry

Thierry Pottier

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Hi Thierry,

I could be mistaking but as far as I know you need reinforced meaning 8mm clearance when using class 2 products. 3mm is only for class I

Disclaimer : I worked with this about 10 years ago so it could be my mind is leaving me

Patrick

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All this depends also on the CE directive that you want to apply. It is not the same EN61010 than EN61750 or others.

Respect to EN61010, if you use a plastic enclosure and there is no metallic part accessible, then you can use 6mm between AC mains related voltage and 'low voltage user side'. 3mm between AC tracks.

Be warned that AC, when rectified directly (like happens with wallmarts or phone chargers), can be accomplished with less creepage distance.

If you mill an slot of about 1.5mm width, then you can decrease those clearences to the half, since then the distance is considered to be 'direct view', and not over a surface. That distinction is important, since the pollution degree (the amound and quality of dust deposited on the electonics) allow for that.

A thorough reading (and re-reading, and reading it again) of the directive that you want to apply is in order.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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Guillem. Yes it make sens, I was working with plastic enclosure (classeII).
Thierry.

Thierry Pottier

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A well behaved 230v is one thing, so s couple mm is probably conservative.

 

Check: http://www.smps.us/pcbtracespacing.html for an idea of what clearance is appropriate.

 

If there is a chance of over voltage events, such as produced by shifting inductive loads, grid issues or atmospheric events, then that needs to be taken into account.  Many standard call for 2 - 20 kV tolerance of an external circuit.  If that is the case, then the clearances need to be against the peak voltage.

https://en.wikipedia.org/wiki/IE...

 

The PCB insulating material is also relevant.

Last Edited: Fri. Dec 29, 2017 - 05:01 PM
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Trivet wrote:
Check: ... for an idea of what clearance is appropriate.
http://www.smps.us/pcbtracespacing.html

 

"Dare to be naïve." - Buckminster Fuller

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I hope the OP is still alive after almost 8 years......cheeky maybe he just electrocuted the clients.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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js wrote:

I hope the OP is still alive after almost 8 years......cheeky maybe he just electrocuted the clients.

must have done lab tests..... and then CE might have been lucky.

but indeed wonder just like you why all of the sudden this reply is posted.

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why all of the sudden this reply is posted.

 

The issue of electrical protection in a circuit is still relevant, even a decade after the OP.

 

It appears that the OP was still posting 4 years later, so presumably survived the design and test process.

The original response was - weak.  Raising the issue might stimulate a more complete response.

 

To be more clear, I have seen a lot of designs that ran 220 VAC traces about 10 micron from processor logic.

Simple trace clearance is one aspect of the issue.  Protecting from voltage surges is also important.

 

Perhaps it is not well understood that the previous posts are a repository of knowledge, not simply responding to an individual request.

Refining the answer over time would seem to continue and hopefully refine the legacy of the OP.

 

There were suggestions that 23 mil, 1.5, 2 -3 mm would be sufficient, but no explanation for where these come from was provided.

 

To me it would seem prudent to provide protection to a 2Kv surge in something that would connect to the grid.

 

One could speculate that the OP was planning to design something that would attach to grid power.

Protecting against the power of a local lightening strike would likely be beyond the reasonable limits of the design.
But a design that would attract energy surges would be imprudent.

 

Given a lightning strike can generate 100 million volts, it would seem that the trick is not to deal with the lightening, but rather to avoid being the best path to ground.

Designing the critical high voltage to 220 volt rules is likely to be insufficient.

 

As mentioned previously, standard ESD testing for 2 - 20 kV is common for most electronics that have exposed circuitry.

Designing to the higher standards would seem prudent.

 

Allowing a one inch trace gap would be prudent for these higher voltages.
However, looking at the design, avoiding the least path might be the standard.
The OP was seeking CE certification, but did not specify the environment or standards to be met.

The dialog might focus on the balance between sufficiency and good design.

Last Edited: Fri. Dec 29, 2017 - 05:08 PM