Michael Loftis wrote: [dd]
> >> The root cause is almost always bad grounding in one building or > >> another. In a couple cases we discovered that ants and termites had > >> colonized around the grounding rod. In another we discovered the > > > > Our electricians say that the grounding is correct, all grounding > > circuits on the site are interconnected and that they measure the > > parameters annually. I am not the person to expose them to be lying > > (if they really are), I lack such qualification. > > Have you checked to see how much potential difference is at one end or > the other? Yes, I have just had it checked at my request. > (Disconnect equipment from one end, and measure voltage > between the various RJ45 pins and ground, should be 0.00) We have checked between the switch ground and the RJ45 pins of the disconnected incoming cables, it's zero. > And how much > current is flowing? (set meter in mA and do same) Zero. > Worse your issue > could be entirely intermittent too. Yes, you're dealing with > gremlins. Just because the individual buildings are OK doesn't mean > they're OK with respect to eachother. You can have grounding > potential differences in different floors of the same building or > different areas of the same building. > > And all of this is assuming it's grounding potential > differences....not something like your bundle of Cat5 runs right by a > big industrial refrigerator, or a sodium light or something like that > which is inductively coupling to your Cat5 run. There is some industrial equipment in the vicinity. That's why we had installed Ethernet protection (which proved ineffective this time). -- Victor Sudakov, VAS4-RIPE, VAS47-RIPN sip:[email protected] _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
