Brian - Aside from current carrying capacity of copper, the presence of solder is a concern.
CSA/UL 60950-1 have requirements to test against for such constructions. These requirements are based on CSA 22.2 No. 0.4 (Limited Short-Circuit Test). Test fault current simulation is based on branch circuit protection sizes and input current rating, with the compliance criteria including successfully opening the branch circuit protection without degradation of the earthing circuit impedance beyond a small percentage. I have performed around six to ten of these tests at the 200 A level. In each case, the circuit breaker I used opened in less than half a cycle. I have experienced no noncompliances. In fact, the earthing impedance _improved_ after the fault condition was imposed. I do not recall the copper weights or trace widths for these products, but they were rated for less than 4.9 A at 240 V. The next higher step in assumed fault current is 1,000 A. Regards, Peter L. Tarver, PE [email protected] > From: Brian Kunde > Sent: Monday, February 05, 2007 6:49 AM > > There was an article in one of the many trade magazines we get a few > years back about running PE or Safety Earth ground traces on a PCB and > how they needed to be designed so not to get damaged during a short or > overcurrent situation. I can't find this article so if anyone help me > out I appreciated it. > > We are using a "Distribution Card" to power AC sub assemblies in our > product. So we want the PE traces in this distribution card to handle > the fault current without damage. The sub assemblies have a fault > current in the 5 to 10 amp range depending on the assembly. > > Our CAD guys just want a current value for the PE so they can > plug into > their computer and it will make the trace width wide enough to handle > the current. So is X2 the fault current enough? I thought the > article I > mentioned above recommended X3 or X4. > > Appreciate any recommendations. > > The Other Brian. > CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. _____________________________________________________________________________ Scanned by Sanmina-SCI eShield _______ _____________________________________________________________________ - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
