I think you are expecting too much from the cart. The ANSI/ESD S20.20 recommend that the resistance to ground from the surface of the moble equipment be less than 1 billion ohms. Are you working with some extrordinary components? To transform the cart into a grounded workstation you would need to connect it to ground with a wire/resistor of appropriate value. Remember dirt and dust prevent good contact with the floor, which is probably greater than 1 Meg Ohm. > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Kane, Joseph > Sent: Tuesday, December 03, 2002 2:29 PM > To: [log in to unmask] > Subject: [TN] ESD-Protective Carts > > > Our stockroom is looking for some carts that are > ESD-protective and ground through the conductive floor > underneath. In other words, we want the cart to be grounded > while moving, so we can transport sensitive parts from the > stock location to the point of use. > > Basic practice says that ESD-sensitive material must be kept > in protective packaging or at a static-protective > workstation. These carts must be considered portable > workstations, so we'd want the surface of the cart to meet > the same grounding criteria as a static mat sitting on a > table. Of course, we'd lay out specific routes to minimize > exposure to fields. > > We've bought some carts that claimed to ground through the > wheels, but they failed test. We tried some metal carts, and > hung chains underneath to drag on the floor, still no good > (not enough contact > pressure?) And even if either of these concepts works now, > what happens after the cart rolls around for a while and the > wheel, or the chain link, or the grounding strap inevitably > picks up a layer of insulating dirt and dust? > > If anyone is using grounded carts successfully, could you > please let me know make and model, how you test and how > often, and how you handle the buildup of insulating dust? > > Joe Kane > BAE SYSTEMS Controls > Johnson City, NY > > --------------------------------------------------- > Technet Mail List provided as a free service by IPC using > LISTSERV 1.8e To unsubscribe, send a message to > [log in to unmask] with following text in the BODY (NOT the > subject field): SIGNOFF Technet To temporarily halt or > (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE > mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest Search the archives of > previous posts at: http://listserv.ipc.org/archives Please > visit IPC web site http://www.ipc.org/html/forum.htm for > additional information, or contact Keach Sasamori at > [log in to unmask] or 847-509-9700 ext.5315 > ----------------------------------------------------- > --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------