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Message-ID: <4FBE8401.8010401@laserlinc.com>
Date: Thu, 24 May 2012 14:54:57 -0400
From: Joshua Lansford <Joshua DOT Lansford AT laserlinc DOT com>
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To: geda-user AT delorie DOT com
Subject: Re: [geda-user] Chassis ground vs Circuit ground
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Reply-To: geda-user AT delorie DOT com

Wow.  We've been going though CE certification on our products for some 
time now.  Never even considered that different certifications could 
conflict.  Oh and yes.  We have had the circuits blown in one of our 
gauges because someone arc welded a bracket or something to it.  We told 
them that that was probably not a good idea. :-p {... hmmm if I arc weld 
my computer to my desk, no one will take it ... and the data will be 
safe... permanently :-) }
~Joshua

On 05/24/2012 11:34 AM, Bob Paddock wrote:
> On Thu, May 24, 2012 at 10:45 AM, Joshua Lansford
> <Joshua DOT Lansford AT laserlinc DOT com>  wrote:
>> Hello.
>>    I have an Ethernet Jack with a separate chassis ground.  The grounds
>> connect by zero ohm resistors beside the jack.  Supposedly this keeps noise
>> from following the cable onto board.  I saw somewhere not connect chassis
>> and  together on the board but though the enclosure.  The card with plated
>> edges slides into a metal extrusion.  Should both edges be chassis ground or
>> should one be circuit ground?   This supposedly keeps a DC difference from
>> developing but dissipates noise.  What are your opinions about how to deal
>> with chassis ground vs circuit ground?
> This is one of those areas that there is no right answer.
> The requirements vary by country and even the industry within the country.
> That is why the zero ohm resistor is there, so it can go either way
> depending on where it is being sent.
>
> Electrically I'd prefer to not have signal ground be chassis ground.
> Chassis ground is a good place to hook up the negative side of your
> Arc Welder (really, I've seen that).  Regulations say they have to be
> connected because my five volt logic might be a shock hazard (compared
> to the Arc Welder?)...
>
> For an example: In Coal Mines in Australia any green colored wire must
> go to Earth Ground.
> So we had to replace our rainbow colored ribbon cables with gray ones
> in our system.
>
>