On Tue, 13 Dec 2011 15:24:31 +0100 "Frank Schuhmann" <f.schuhm...@t-online.de> wrote:
> >> At their website soekris is telling something about for what the boxes > >> are to > >> use: > >> 1. Small net services > >> 2. Small routers / servers / vpn / wlan > > > >I'm using my net5501 as a router. And as i said, WLAN crashes the machine. So > i'm using it in a way that is not expected??? > > What is with the wm (milliwatt) power of the WLAN card? Dont know. But these devices usually have less than 1W peak. > Too much, let the device turning quickly to hot? Definitly not. It's in a constant air stream. > >Err... I'm not sure i understand you correctly... > >But, if you really have a full lightning strike on your alix/soekris box and > have the case melting... then the molten metal is the least of your problems > as > anyone near the box will be already dead. > >Beside, that the iron sheet of the soekris box will melt as well. > > No aluminum cases in business installs please, in some or few cases this is > perhaps ok, but not usual. > Drilling a little hole at the back side of the soekris box to connect an > electric ground cable from the soekris box to the rack will prevent the > soekris > box from smelting, but not an aluminum case. Er.. get yourself a better phyiscs book. This wire will not protect anything from melting. The wire will evaporate long before the case even gets hot, due to much higher electrical resistance. The reason why metal cases are earthed is to prevent them from building up electrostatic charge and in case the device inside is faulty and has a mains short circuit to the case. And a little math to prove my point here: Assuming we have a light alu case of 100g weight, it will take about 54kJ or 54kWs to get the case to melting temperature (ie it is still hard). Any wire that conducts that much energy will be long evaporated before the case gets to that temperature. And mind you, it needs another 40kJ to melt the case. And even assuming you can melt the case just with an lightning strike and not fry everything around it, then there is still the aluminium oxide layer which will hold the molten aluminum together until it melts itself (at about 2000°C) > Several meters > to open a windows, to let the smoke out only was be done by a wet t-shirt over > the face. > The metal plated server cases were in one part, sure with electric fire marks > at > some places, but the both aluminum cases were looking like toasted bacon with > smelted cheese on the boards. > Nearly the whole device structure was totally damaged, the rack door windows > were spread out all over the room, ok it was a secure window only little but > very sharpen shards were going over the whole room. That rather sounds like the lightning strike caused a little fire that burned something inside the rack. And if you get that far and your automatic fire extinguisher doesn't properly work (given you have one), then it's not the fault of the case. > Nobody was working in this > room (only for server racks and too cold to work la long time in) If you made > other experiences, you are perhaps a lucky one. Not anymore lucky, then lucky enough to work at companies who value the security of their employees enough to have proper earth connections on everything and every cable comming from outside is passing trough a lightning arrestor. > For the metal case based hardware the insurance will pay but not for the > aluminum cases, ok later they were paying also for this because the electric > prevention installation was made false (not deep > enough inside the ground at the outside of the building!!! Perhaps in other > countries there are other laws and house or environment insurance and they are > paying even all, likes in the country you are acting and working. You live in germany, you've the same regulations as we do in switzerland. And that the lightning rod was not earthed properly is definitly a big issue and cannot be blamed on any alu case. And i doubt that the insurance company will not pay due to the use of aluminum cases. If it there would be a risk of melting of alu cases, then there would be a regulation for this. And i'm not aware of any. In the contrary, there are even lightning arrestors sold that use aluminium cases. How could they work if the case would melt at the smalest hit? http://www.radiolabs.com/products/antennas/accessories/lightning-protection.php Anyways.. i dont belive you that the case melted due to the lightning strike directly. Especially not if you are telling me that a steal case would not have melted. If this incidence is true, show us some pictures. > Trust me or not after this event, nobody 50 - 80 km around Hannover will tell > you it is a good choice to store a aluminum based case inside a business > network > environment for a very long time. I know a few sysadmins from the Hannover area. Nobody has heard of this incident. > Last but not least Attila let me tell you that my English is not very well > formed and is purely wide distances away from native speaking and if a word is > placed plain in a text some people may thinking > that I will kidding only them, at this point, no I don´t want to do so, but > with > my English I need mostly more than some few words to explain what I mean. And > I > think this is a tech list and no chat room. You can write to me in german if you want. But yes, we should stop this "discussion" here.... Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin _______________________________________________ Soekris-tech mailing list Soekris-tech@lists.soekris.com http://lists.soekris.com/mailman/listinfo/soekris-tech
