Re: [CAD_CAM_EDM_DRO] Re:More on Re: Insulating D-shell from chassis?

To all;

Floating an metalic shell of any type at an external panel box
transisiton is bad practice for two reasons. One it is a safety
hazard if wire of a high potential come into contact with the shell.
Most likely you will run afoul of the law somewhere doing this.
Having ungrounded metalic parts on a panel box is just inviting
problems. The second issue is electircal noise as opposed to ground
loops. You do not want the shell radiating emmissions.

Clearly plastic connectors are just that plastic and in most cases non
conductive. A non conductive shell will not have the problems that a
metalic shell will have. It should be noted though that many of the
plastic shells do have their threads grounded for cable attachment so
you can still have ground loop issues with them.

It should also be noted that once you isolate a shell like has been
described you also end up with the issue of keeping that isolation
intact. Not an easy task on metal working machines.

Thanks
Dave


ballendo wrote:

>Don,
>
>Why do you say that? What is wrong with floating the shell of the
>dsub? We routinely isolate low level signals (and grounds) in
>multiple cabinets industrially in this fashion. As Randy said, what
>about the fully plastic dsub connectors? Are these also a bypass?
>
>I am truly curious as to what you feel is wrong about this solution
>(I call it a fix). What electrical or safety "rule(s)" does it break,
>or bend?
>
>Thank you in advance,
>
>Ballendo
>
>--- In CAD_CAM_EDM_DRO@yahoogroups.com, Don Rogers <Don@C...> wrote:
>
>
>>Back when I was in computer development, there were two answers to
>>
>>
>a known problem. The first was a 'bypass, or a way to get around the
>problem" the second was "Fix".
>
>
>>I'm sure the floating the DB25 shell is a bypass, not a Fix.
>>
>>Don
>>
>>