| Forum Home | ||||
| Press F1 | ||||
| Thread ID: 26411 | 2002-10-26 21:10:00 | Underground Phone Cables | Danger (287) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 93310 | 2002-10-27 01:11:00 | Godfather, Can i ask your opinion on this? What about those of us on Cable modems? All my services come in underground. I have 2 telstra phone lines, but that is for speech. I do not connect any resident computer to any phone line and get my internet connectivity through a cable modem. The cables in my street are entirely underground for both power and phone, but telstras cables in ajoining streets are above ground for the moment, hanging just under the power cables. From what i can work out, the power for my house is coming of one of the transformers that runs part of the Jade Stadium complex, and none of the ajoining streets overhead stuff is connected to the said transformer (i could be wrong). I have noticed that Telstra hang their cables on a 16mm2(?) guy wire that is earthed every 2nd pole with a 6mm2 earth wire and earth stake. How safe am i from lightning damage? |
Clueless (181) | ||
| 93311 | 2002-10-27 01:18:00 | simaler risk to those with modems. cable surge protectors are advailable (as are tv aerial, lan etc) | tweak'e (174) | ||
| 93312 | 2002-10-27 01:24:00 | So if i get the hell surge through the cable, obviously first in line is telstras cable modem, but what are the chances of hell spikes finding their way past this device, and through the cat5 to the first of my computers? | Clueless (181) | ||
| 93313 | 2002-10-27 01:24:00 | Good point Clueless. One would need to see the internal circuitry of the cable modem (and any ADSL modem for that matter) to see whats connected to what. A close lightning strike (and as I type this I hear sounds on the radio indicating the cold front over your area has lightning) would I suspect be no different to a phone circuit. ADSL technically could connect wia a very small capacitance given its frequency, as could cable. But how they would connect is another matter. And how you could protect the system is unknown, unless we see the circuit. The catenary will indeed be earthed on cable, but this is no guarantee however as EPR could raise that dramatically If there is a major fault or a strike, remember to stand on one leg, so you dont act as a potential divider! What we need is something from H2G2 (HitchHikers Guide to the Galaxy) where impending doom can be sensed and a reaction take place just before it actually happens (panic sensitive glasses) |
godfather (25) | ||
| 93314 | 2002-10-27 01:38:00 | I was told by the Telstra rep, (who is/was very much a saleman, and has a bright future with DSE) that part of how the cable network works is that there is a fibre optic cable that is hung/buried around the streets and there is a wee "tapping" at every other house where the coax cable was connected. To the best of my knowledge fibre optic cables are not the greatest conducters of electricity, even freak stuff like lightning... Of course this could be a lot of sales talk.. the only part of what he said which i beleive to be true was "free connection" (as opposed to telecons $240 charge to move 2 numbers from exsiting lines at one street entrance where the relevant building was being demolished, to exsisting dead lines at my other street entrance where the building has remained.) BTW.. the sky has fell we have been lightning, thundered, rained and hailed upon, and i'm inside on the computer.. what a lovely day it started as. |
Clueless (181) | ||
| 93315 | 2002-10-27 02:02:00 | Fibre optic is of course a good insulator - but you cannot "just connect a coax to it" as the salesman would like to think. There are many types of fibre optic cables, and many have an armouring sheath (metallic) around them which is a wonderful conductor..... What we need is a fibre optic isolated I/O for the PC, so no outside circuits are terminated there (or do we, how many PCs have you had fried due to power, lightning?) |
godfather (25) | ||
| 93316 | 2002-10-27 02:16:00 | Dyan (my better½) lost one about a year ago, due to lightning strike . This is in Cobden Greymouth . She had unplugged it from the mains, but left the modem connected to the phone line . It fried the modem and motherboard, so the machine was a rightoff . The insurance claim was such that the unit was replaced with a beast that was 4 times everything, 10 times HDD space, and had a complimentry scanner and printer . . . . So she wasn't too worried . My sons and his mother lost the modem through lightning strike on the phone line . This one was seriously rural being Seddinville also on the West coast . Me personally . . . I haven't lost anything (yet) . I kind of feel a little bit protected by looking out the front of my house and seeing 4 HUGE lightning rods that double as the lighting towers of Jade . If anything got hit around here, i figure it would be them, and that would leave the communications/power infrastructure alone . This does have me questioning the wisdom of hanging cat 5 between buildings etc . |
Clueless (181) | ||
| 93317 | 2002-10-27 02:23:00 | In both the cases above the phone lines were overhead for 100mtres or so between local underground cable and effected dwelling. In the Seddinville case the cental cable was only buried through the township itself, and the feed to Seddinvile from the Mokinui exchange was overhead and around the side of hills |
Clueless (181) | ||
| 93318 | 2002-10-27 02:58:00 | i doubt they would have fibre down the street. fibre optic cable is exspencise. most likely down the street would be coax but there would be nodes where a number of the streets are connected to the backbone. the backbone could well be fibre optics. i've had a case of lightening thats gone down the phone lines and back through the lan card. |
tweak'e (174) | ||
| 93319 | 2002-10-27 03:08:00 | I often wonder though: If a lighting strike made it through 1Km of air [not a bad insulator], then a piddly little protector/diverter in your house ain't going to make a lot of difference to several millions of volts. However such protection will help to stop any induced voltages caused by the lightning. I suspect that most damage is caused by such events [induced voltages] rather than the lightning strike itself. If one gets a direct strike [rather rare ] on your house or cable going to your house then no amount of surge protection is going to help. Extremely High Voltages does some wierd things so nothing is a given in the form of protection. In other words, it is statisically highly probable that a lightning strike will choose a lightning rod/high structure rather than my humble abode, but not impossible. 42 |
~42~ (2034) | ||
| 1 2 3 4 | |||||