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<p.blo...@dreki.de> 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 -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Etiquette is for those with no breeding; fashion for those with no taste. ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
