# Why Don't the Phone Lines Go Down? **URL:** \ **Category:** Factual Questions\ **Created:** [September 12, 2011, 3:55pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064 "2011-09-12T15:55:02Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [September 12, 2011, 3:55pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/1 "2011-09-12T15:55:02Z")
Whenever there’s a major storm you hear of - and sometimes experience - power lines going down all over the place. But I don’t recall hearing about - and certainly have never experienced - phone lines going down in a storm. Which is not to say it never happens - I have no doubt that it does. But it seems to be a lot less common than power lines going down, and I was wondering if there’s a reason for this. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [September 12, 2011, 4:01pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/2 "2011-09-12T16:01:26Z")
the phone company has huge amounts of batteries and generators to power the landline phone system when the electrical grid goes down. if the phone lines are elevated then a storm that takes down power poles would take down these as well. if the phone lines are buried then they are more protected. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [September 12, 2011, 4:09pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/3 "2011-09-12T16:09:28Z")
> [@Fotheringay-Phipps](#): > > Whenever there’s a major storm you hear of - and sometimes experience - power lines going down all over the place. But I don’t recall hearing about - and certainly have never experienced - phone lines going down in a storm. > > Which is not to say it never happens - I have no doubt that it does. But it seems to be a lot less common than power lines going down, and I was wondering if there’s a reason for this. Certainly in horror movies (pre-cell phone), the phone lines were always going down in storms 🙂 But yeah, the phone company supplies their own power. So it’s less common for phones to go out unless the line break is directly between you and the local phone switch. ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [September 12, 2011, 4:12pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/4 "2011-09-12T16:12:19Z")
I don’t understand these answers. I wasn’t asking why the power lines going down doesn’t automatically makes the phones stop working. I was asking why the phone lines don’t go down as frequently as the power lines. Both the phone company and the power company produce their own power and send it through the streets to individual homes. Why does the chain tend to get broken in one case much more than the other? ---
**Author:** ![Jas09](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@Jas09](https://boards.straightdope.com/u/Jas09)\ **Post date:** [September 12, 2011, 4:14pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/5 "2011-09-12T16:14:28Z")
Also aren’t telephone wires on poles insulated, unlike power lines. So power lines falling to the ground will cut out power, but telephone wires falling to the ground (if they don’t physically break) will not cause a loss of service. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [September 12, 2011, 4:17pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/6 "2011-09-12T16:17:35Z")
In my back yard, the power lines are at the top of the pole, maybe 40 feet up. The phone lines are much lower, maybe 20 feet. So the higher lines will be exposed more. A couple years ago, a utility pole in the neighbor’s yard decided to shift on its foundation. The top swung about three feet off vertical, and the power lines actually snapped. We lost power for 8 hours while they had to drive in a new pole and repair and rehang the lines. But the pole didn’t swing nearly as far where the phone lines were attached, and there was enough slack to keep them from breaking. Plus, you’ll hear more about power lines because it’s unlikely stepping on a downed phone line will kill you. ---
**Author:** ![Jas09](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@Jas09](https://boards.straightdope.com/u/Jas09)\ **Post date:** [September 12, 2011, 4:20pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/7 "2011-09-12T16:20:43Z")
Lots of interesting facts and diagrams about utility poles here: [UTILITY POLES](http://annsgarden.com/poles/poles.htm) It illustrates **kunilou** ’s point about how less exposed communication lines are than power lines. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [September 12, 2011, 4:21pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/8 "2011-09-12T16:21:33Z")
I’ll give you a possible factor and a data point. About a week ago, my power was out for about a day when a neighbor’s tree fell on the power line. The phone line did not go out, and if I go out in my back yard, and look at the utility poles, I can observe that the phone lines are placed much lower on the pole than the power lines. In this situation, a falling tree is far more likely to take out the power line than the phone line, and this arrangement is common practice: [http://annsgarden.com/poles/poles.htm](http://annsgarden.com/poles/poles.htm) Add to this, that a lot of phone wires ARE underground. ETA: Hmmm. Lovely triple simulpost. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [September 12, 2011, 4:32pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/9 "2011-09-12T16:32:00Z")
Phone lines are insulated. Power lines aren’t. If a tree branch blows against a phone line, not much happens as long as the branch doesn’t physically damage the line. If a tree branch blows against a power line, it shorts out the line and the power goes out. Also, phone line wires go from your home to the nearest CO, which usually isn’t all that far away. From there, you have multiple branches out to the rest of the world. If a falling tree limb knocks out one trunk cable, the CO just uses a different one to route the calls through. If the CO gets busy and runs out of circuits in and out you might get a busy signal, but most of the time your call will still go through. Your power lines typically run for much longer distances, and if the power company loses a main transmission line, huge areas may end up without power. The phone company’s lines are naturally redundant because they need to branch out and communicate all over the place anyway. Power lines are only redundant to the point that the power company feels they need them to be. ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [September 12, 2011, 4:38pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/10 "2011-09-12T16:38:31Z")
Basically, the telephone companies have, over the last hundred years, put an amazing amount of time, money, and sweat into hardening their systems and providing multiple redundancies. In some cases, the work they have done has opened or broadened entire mathematical and engineering disciplines. Up time is their stock in trade. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [September 12, 2011, 4:48pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/11 "2011-09-12T16:48:27Z")
Power lines also run as much higher voltages than telephone lines do. Power outages are frequently caused not by downed wires but by a temporary short circuit — a tree branch touching two lines, say, or some kind of physical impact causing two poorly-insulated wires in a junction box or transformer to start conducting. When this happens, safety devices (fuses, more or less) cut the affected section off from the grid, and the power crews have to come out and reset things. The phone lines, on the other hand, don’t have positive and negative wires widely separated — as noted in the above link, all the lines are in the same strand, and the lower voltages present mean that (all other things being equal) the same jolt is much less likely to cause a short in the phone line. ---
**Author:** ![suranyi](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@suranyi](https://boards.straightdope.com/u/suranyi)\ **Post date:** [September 12, 2011, 4:49pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/12 "2011-09-12T16:49:47Z")
My phone line went down after the Loma Prieta earthquake of 1989. So they aren’t immune to every natural disaster. ---
**Author:** ![Tom\_Tildrum](https://avatars.discourse-cdn.com/v4/letter/t/e95f7d/32.png) [@Tom\_Tildrum](https://boards.straightdope.com/u/Tom_Tildrum)\ **Post date:** [September 12, 2011, 4:57pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/13 "2011-09-12T16:57:08Z")
Why are phone lines insulated but not power lines? ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [September 12, 2011, 5:02pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/14 "2011-09-12T17:02:47Z")
> [@Tom\_Tildrum](#): > > Why are phone lines insulated but not power lines? Phone lines contain bundles of small wires that all need to be insulated from each other. Power lines are just one big wire. ---
**Author:** ![Jas09](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@Jas09](https://boards.straightdope.com/u/Jas09)\ **Post date:** [September 12, 2011, 5:04pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/15 "2011-09-12T17:04:18Z")
> [@Tom\_Tildrum](#): > > Why are phone lines insulated but not power lines? I believe at the voltages present in high- and medium-tension power lines the insulation required would be unwieldy and very pricey. Communications lines require it to function properly, and are often bundles of independent wires (some twisted-pairs, some coax, some fibre). ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [September 12, 2011, 5:07pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/16 "2011-09-12T17:07:05Z")
> [@Fotheringay-Phipps](#): > > I don’t understand these answers. I wasn’t asking why the power lines going down doesn’t automatically makes the phones stop working. I was asking why the phone lines don’t go down as frequently as the power lines. who says they don’t? electrical power outages make the news more because so much critical stuff depends on it (food safety, medical equipment, and the like.) A phone outage isn’t likely to be as immediately critical especially with so many people having cell phones now. ---
**Author:** ![Muffin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muffin/32/4341_2.png) [@Muffin](https://boards.straightdope.com/u/Muffin)\ **Post date:** [September 12, 2011, 5:09pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/17 "2011-09-12T17:09:20Z")
My phone/internet goes out more frequently than my power. It goes out on its own, and it also goes out when the power goes out. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [September 12, 2011, 5:10pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/18 "2011-09-12T17:10:51Z")
I wonder if phone outages happen more often than we realize. If the power goes out even for just a few seconds, I’d notice immediately. But if the phone goes out for a few hours, there’s a good chance I wouldn’t notice. ---
**Author:** ![BubbaDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bubbadog/32/333_2.png) [@BubbaDog](https://boards.straightdope.com/u/BubbaDog)\ **Post date:** [September 12, 2011, 5:11pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/19 "2011-09-12T17:11:24Z")
> [@Tom\_Tildrum](#): > > Why are phone lines insulated but not power lines? [A recent thread on this.](http://boards.straightdope.com/sdmb/showthread.php?t=622628) ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [September 12, 2011, 5:11pm UTC](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064/20 "2011-09-12T17:11:39Z")
You basic stantard POTS (Plain Old Telephone System) is a pair of wires that run from the nearest substation building to your house. One wire, just for you - if that wire is not interupted (cut or grounded) then your phone will keep running. Odds are, too, in a larger urban area, the trunk lines between the substations are now fibre buried undergrund, so if your neighbourhood line is not down, the phone system stays up. If one trunk line dies, well, the phone system like the internet is often configured with multiple paths and flexible routing for problem recovery. The phone cable provides enough voltage and current to power a basic touch-tone phone. The central substation has battery-backup to support this during blackouts. Phone lines, being a collection of dozens of tiny thin cables, are usually strung with a strong wire messenger cable to hold the load and tension. Not sure about power, but I doubt tying a big power line to a separate bare metal cable is ever a good idea. Power, OTOH, is sort of like the water distribution system - one big feeder cable feeds an area, where it is then dropped down to 220V (whatever) at a transofrmer, and each house in the area is fed with a tap from from that same wire. SO any interruption anywhere in the system stops feeding the whole area, just like a broken watermain could mean no pressure for the whole neighbourhood. Of course, large distribution points are fed by high voltage lines from multiple sources, but in a difficult time, if one or more feeds goes down, it may overload the other feeds. Since they will be breaker-protected from excessive load, area blackouts are often triggered by an event that then causes cascading failures through the distribution system. Your phone either works or does not (or is very noisy, but works). The electricity system has to handle anything from a tiny load to a city full of simultaneous cooking and air conditioning. What might be acceptable load in normal times could be overload if everyone fires up a big load at once. The electrical system is more vulnerable. (Jerry Pournelle about 15 years ago described an incident where someone a few blocks away hit a power pole; this caused a 6000V line to drop onto the regular 220V distribution line, causing light bulbs to explode, electronics to fry, and general appliance failure for several blocks around. He was impressed that the UPS units protected some of his computer equipment from this “event”.) [Next page](https://boards.straightdope.com/t/why-dont-the-phone-lines-go-down/596064.md?page=2)