Steve Wright wrote: > Vik Olliver wrote: > >> >> I'm still puzzled as to why people are worried about voltage >> differentials on Ethernet. It's a floating signal with 2KV of line >> isolation. Can anyone actually come up with a definitive reference as to >> why this is not sufficient for strapping two home networks together? >> I've designed Ethernet cards, installed numerous cross-phase >> installations and never, ever had a problem. >> > > Nope. Just go work for someone in the generation industry for a while > and find out the hard way, or get your ear burnt off by some senior > technician wailing on about how dangerous this is. Yes, these are the same people who worked out that the Titanic would never sink. Having work with a metro ethernet provider for many years, it turns out that the way the Taiwanese electronics industry avoids returns it to make products practically indestructible. So strange kamaguza ethernet hubs/switches/rj45 things do indeed have excellent isolation, on every input/output. The danger with running long cables is not the long cable per-se, but standing current, and "supposedly" connecting two residences together that are supplied on different phases of 240v. High current flows through cables arising out of differing earth potentials of the two locations, and/or standing current due to phase differences. Standing current is avoided because of the isolation transformers. The two phase thing seems to be not a problem due to isolated supplies (the funny little plug pack thing) and also the isolation transformers itself. The other major reason for "THE IDEA" that you should not do this was that (just supposing that the two houses were connected in such a manner that there was a 50V earth differential, and large standing current) was the equipment within each location was EXPENSIVE. This has been completely blown away by FREE 10Mb hubs, which is what I would venture most readers of this list are using, where "FREE" was because the 10Mb things were replace with 100Mb switches in the organisation, so the 10Mb hub was worthless. So the consequences of failure/destruction of a 10Mb hub are..... ?????? (at least $50 @DSE) 2c worth, from someone who has run 10Mb ethernet down the street, onto a power pole (10Mb hub on pole) and another 100 yards down to a colleague. Been running quite happily for just over two years. (no don't ask, perfectly legal, done by a licensed carrier). Wire is good. GigE UTP is good (you don't have to share it with anyone). WiFI and ADSL are OK today, but they are just the modern modem equivalents, just a two year stop on the way to your personal colour... I venture there will be 8 port fibre Gig switches at the $79.95 price within the next 12 months, at which point all of this goes away.... Roger > > Geeks have no idea of the consequences of running a wire this long, and > I could go <OT> here and lecture for hours on the stupidity of said long > wire, but I won't. > > A wireless card is only $115, and if that is not fast enough, then put > some fibre in. DON'T run a long wire. (ever wondered why you should > stand clear of the telephone on the wall during a storm?) > > > /sw > > ------------------------------------------------------------------- > To remove yourself from this list, email nzlug-request@linux.net.nz > with "unsubscribe" in the body of the message. > -- \_ Roger De Salis rdesalis@fx.net.nz </' FX Networks +64 25 481 452 /) Wellington, New Zealand roger@desalis.gen.nz (/ ` Bentley win Le Mans! - What next, English win cricket in Aus? ------------------------------------------------------------------- To remove yourself from this list, email nzlug-request@linux.net.nz with "unsubscribe" in the body of the message.
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