On 10/4/2011 1:31 PM, gene heskett wrote: > On Tuesday, October 04, 2011 01:04:56 PM Dave did opine: > > >> On 10/4/2011 11:23 AM, gene heskett wrote: >> >>> On Tuesday, October 04, 2011 10:55:18 AM Peter Blodow did opine: >>> >>>> andy pugh schrieb: >>>> >>>>> On 4 October 2011 07:31, Peter Blodow<[email protected]> wrote: >>>>> >>>>>> I hoped Jim Coleman would be the one looking like an idiot.... but >>>>>> couldn't someone explain to a poor non-US citizen what kind of >>>>>> animals RCD and GFCI are? >>>>>> >>>>> Does "Fehlerstromschutzschalter" make any more sense? >>>>> >>>>> http://de.wikipedia.org/wiki/Fehlerstromschutzschalter >>>>> >>>> Thanks, Andy, of course I know these. I have experienced a lot of >>>> unnecessary trouble caused by this safety switch during my time as a >>>> facility manager as well as at home (freezer connected to the same >>>> line as the kitchen appliances, protected by such a goody, us being >>>> on holidays, and a lightning striking nearby)... >>>> >>> A Hint Peter. I have, scattered about my premises, a dozen or more of >>> those 3 foot long plugin extension strips with 6 to 8 sockets, a cheap >>> circuit breaker and surge absorbtion (65+ Joules) built in. 20 years >>> ago I used to lose a modem every time mother nature put on a show. >>> So I first went through this room and made sure all the wiring was >>> tight, and properly phased. Then I bought one super deluxe version >>> of this gizmo, plugged it into the duplex behind this desk and hung >>> it on the wall about 4 feet from me. It has connections for cable tv >>> and telephone too, so all circuits are protected by the devices 5500 >>> Joule surge absorber. Except for the X10 stuff and the overhead >>> lights, everything else in this room is plugged into this as a >>> central, common point. If lightning does strike, then the whole >>> rooms electrical stuff "bounces" in unison. >>> >>> Now I do not have cable anymore, so I have only the 8 or 9 channels I >>> can get from a roof mounted, rotating antenna, which is itself >>> grounded from its base and all 4 guy wires. There is a telco type >>> lightning arrestor connected by 2 feet of 8 gage to a ground rod, as >>> is the coax from the antenna. With lightning arresters on the rotor >>> cable as well as the coax, I saw evidence of a strike on the antenna >>> the wind took down last June 24th, but it didn't get past the >>> grounding and the arrestors. >>> >>> But its been 15 years since I've had any lightning damages, including >>> seeing the pole with my transformer on it take a good hit at least >>> once. >>> >>> The rest of the house is similarly equipt with these surge arresting >>> circuit expansion strips too as I've made sure any wiring expansions >>> or such that I have done are so equipt. >>> >>> I sleep better when the weather gets ugly. I seem to have the damages >>> under control. Extra expense over about 20 years might be $150. >>> >>> Cheers, Gene >>> >> I was having the same problem years ago - lightning strikes on the power >> lines taking out equipment. >> I found a Square D surge suppressor that mounts directly in the power >> subpanel that powers my computers. It installs just like a circuit >> breaker. Ever since I did that installation I have had zero failures >> due to lightning storms. Before the surge suppressor I was losing >> computers and electronic equipment on a regular basis during lightning >> storms. I think the suppressor was about $75 on sale. >> >> Dave >> >> > I also thought along those lines Dave, but then I reconsidered because of > the impedance that the long runs from the electrical service also represent > a rather effective antenna for the EMP the lightning strike introduces to > the system, and based on that, elected to let each individual tree of the > distribution be its own 'common point'. So there is one tree here in the > coyote's den, another pair on the kitchen counters, and one behind the > entertainment center, so no one individual device is more than the length > of its power cord from the common, can't go above about 165 volts peak away > from its neighbors that it may have an audio or video cable connected to as > long as the varistor devices themselves survive. > > When one has spent most of his working life in broadcast, the RF end of it, > and its dependence on the length of the wire involved tends to effect ones > thinking. That 6 to 8 foot run from the electrical entrance service box to > the ground rods that are supposed to be connected there, can in fact be a > several thousand ohm resistance, at the rise and fall times of a lightning > strike which is normally said to be in the nanosecond range when the strike > is close. In my mind it made more sense that everything interconnected in > a given room should bounce in unison, tied together by the conduction of > the varistor in that rooms surge absorber, so that while the whole room > might bounce 100 kilovolts from ground, it is all in unison with no > interdevice surge exceeding maybe 200 volts. It is the interdevice > voltages that blows stuff, but as long as there is air enough to prevent a > direct jump to ground or whatever is handy, and I have a basement under me > so a true ground is about 10 feet away, there has been no local discharge, > except maybe to me. I have felt the field once or twice, but so far have > not been 'doorknob' zapped by my proximity. Probably lucky, but... > > FWIW, I woke up this morning and realized that I had now completed 77 trips > of this planet around its star. > > Someone said another year older& wiser and I replied that the wiser part > was debatable. ;-) > > Am I still the official oldest fart here?, I've forgotten. That too, goes > with the years. :( > > Cheers, Gene >
Happy Birthday Gene! Dave ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
