The internet is a momemtary style fad. A di-electric withstand rating of 1500V will suffice only for Class I construction, where all devices have a reliable ground bound, and for 120V mains, and all wiring connections internal to structure.
There are other issues to consider for external wiring connections and/or for Class II construction and/or for various OV categories. Also, NFPA70 has much to say on this type of wiring. FWIW, my mot surfboard cable modem is rated 4kV, but not all models are... From: [email protected] [mailto:[email protected]]On Behalf Of Goedderz, Jim Sent: Friday, September 11, 2009 10:15 AM To: [email protected] Subject: Additional electrical requirements - isolation Forum, Thank you for your (pending) inputs. Internet connectivity seems to be all the rage lately, and there is a not so obvious question that I would like to get feedback on. Consider an IEEE802.3af compatible camera accessed by going to its IP address. Perhaps a "Nanny cam" of sorts. The intended use is to have a camera in each room of your home, so you use a switching device (router) that is powered by an external brick and also provide some power injection for the rooms where you need a bit more than what POE can provide. The brick is 48Vdc and is a Listed ITE power supply with LPS out. So far, it seems pretty straight forward. The camera is Listed as ITE to be powered by a certified limited power source and that will provide the 1500V isolation from the mains called for in IEEE802.3af. Now consider that the system in your home is connected by Ethernet to the WWW so that you can check in from work. The Ethernet connection comes into your home on a DSL, cable, satellite system or some kind of router which would meet the 1500V isolation requirement. Are the Additional Electrical Specifications, Isolation, para 33.4 of IEEE802.3af (1500Vdc hipot) satisfied by the input power connection and the router. It wouldn't seem necessary that the cameras themselves need to provide 1500Vdc isolation from their Ethernet connection to SELV. Bottom line, would the system as described be considered compliant with IEEE802.3af? Would the camera be considered compliant with IEEE802.3af? Thanks again. Jim Goedderz Sr. Principal Engineer Product Safety Engineer Tyco Safety Products/Sensormatic [email protected] - 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://www.ieeecommunities.org/emc-pstc 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]>
