> The short circuit current wouldn't be much greater > than rated current for any length of time, because > the source is the power supply, not the ac mains.
Typical brick-type power supplies will put out about twice rated current into a short-circuit. So, 10 A rated becomes 20 A short-circuit. Wire size is usually based on rated current. Supposedly, short-circuit current can only exist for a short period of time due to the overcurrent protection -- the short time for operation of the overcurrent device being less than that necessary to overheat the wire insulation. However, brick-type power supplies typically don't have overcurrent protection on the output. Without overcurrent protection, the safety professional must judge whether to size the wire for rated conditions or short-circuit conditions. Richard Nute Product Safety Consultant Vancouver, Washington, USA - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]>
