# What are the Black Lumpy Things on power lines? **URL:** \ **Category:** Factual Questions\ **Created:** [November 4, 2002, 2:35am UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168 "2002-11-04T02:35:31Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![minor7flat5](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/minor7flat5/32/258_2.png) [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)\ **Post date:** [November 4, 2002, 2:35am UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/1 "2002-11-04T02:35:31Z")
Here’s a [picture](http://www.lbstone.com/photos/view.php?photo=power_lines-800.jpg)… The thing I am curious about is the long fat block in the lower-left side of the image. I see these all over the place, usually a third of the way between two poles. Unfortunately, I wasn’t able to come up with a useful Google query for the things. I have always thought that they are some sort of ugly fat splice, but they seem too big and numerous for that. What are they? What is their purpose? ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [November 4, 2002, 2:52am UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/2 "2002-11-04T02:52:52Z")
Well, those are not power lines. They are most likely telephone lines. The black lumpy thing is a splice/junction box. The reason that they are large like that is to make room for the connection of many little wires inside that large cable. ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [November 4, 2002, 2:35pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/3 "2002-11-04T14:35:08Z")
Unless I’m mistaken, that’s a fuse. It’s to isolate shorts in the event of a downed line, cutting off the damaged part from the rest of the grid. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [November 4, 2002, 2:38pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/4 "2002-11-04T14:38:11Z")
> [@](#): > > \*Originally posted by AndrewL \* > \*\*Unless I’m mistaken, that’s a fuse. It’s to isolate shorts in the event of a downed line, cutting off the damaged part from the rest of the grid. \*\* You are mistaken, because those are not power wires on the lower wrungs of the utility pole. Looking at the picture, the top most lines are power, the middle lines are cable (TV and possibly internet) and the bottom lines are phone service. ---
**Author:** ![SoulFrost](https://avatars.discourse-cdn.com/v4/letter/s/f07891/32.png) [@SoulFrost](https://boards.straightdope.com/u/SoulFrost)\ **Post date:** [November 4, 2002, 4:45pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/5 "2002-11-04T16:45:34Z")
The company I used to work for was interested only in the power-grid equipment on the poles. However, those black lumpy thingees were described to me as cable-TV boosters. Not really our job to worry about them, so that description may be inaccurate. Those _are_ on the cable lines, though, and not the power lines. A power line fuse should be easy to spot on any pole that has a transformer (or other equipment) on it. They normally appear as fairly thin gray rods with a series of raised sections… similar to a lightning arrester. I just re-read what I wrote-- and I see why you opted for a picture. Kinda hard to describe these things. -David ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [November 4, 2002, 4:45pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/6 "2002-11-04T16:45:39Z")
Yeah, where the poles are shared, the power’s at the top while the second and third tires are telephone and cable. In St. Louis the phone’s in the middle and cable’s on the bottom. My initial thought reading the post title was that the black thing’s were birds! ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [November 4, 2002, 5:31pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/7 "2002-11-04T17:31:38Z")
Same thing as the white lumps in spider webs. Means they caught a squirrel. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [November 4, 2002, 10:05pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/8 "2002-11-04T22:05:32Z")
I agree with scotth - it’s a splice box. The fairly fat cable contains a bunch of phone lines, each is a twisted pair of copper wires. This point was where they had to join the cable on the left with the cable on the right, and the lumpy thing is a bunch of splices, sealed up. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 4, 2002, 11:19pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/9 "2002-11-04T23:19:36Z")
In addition to the splice, there also needs to be a clamp system to physically hold the two bits of cable together against the stress of the lines weight. ---
**Author:** ![minor7flat5](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/minor7flat5/32/258_2.png) [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)\ **Post date:** [November 5, 2002, 2:04am UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/10 "2002-11-05T02:04:16Z")
> [@](#): > > \*Originally posted by GaryM \* > **Yeah, where the poles are shared, the power’s at the top while the second and third tires are telephone and cable.** Thanks for the info, **scotth** and **GaryM**. Armed with this newly-gained knowledge, I will pay special attention to the black lumpy things on my way to work. That photo doesn’t appear exactly like the ones I had in mind, but it was the first picture I found on the net. If I see one that is a better example, I’ll post a photo of it for your analysis. > [@](#): > > _Originally posted by Squink_ > **In addition to the splice, there also needs to be a clamp system to physically hold the two bits of cable together against the stress of the lines weight.** That’s kind of what I had in mind. I’m going to look and see if I can spot these in the top wires. Does anyone in the business have a link they could offer to a supplier of such splice boxes? I am interested in seeing the inside of one of those things. ---
**Author:** ![UncleBeer](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)\ **Post date:** [November 7, 2002, 6:22pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/11 "2002-11-07T18:22:38Z")
That’s not a splice box. Splice box is a term reserved for enclosures inside which fiber optic conductors are, well, spliced. That box is on a telephone company (telco) conductor and is technically called a “polemounted twisted-pair cross-connection cabinet.” Here’s a picure of the [inside of one](http://www.marconi.com/media/RFP-0117.pdf) in pdf format. The pole you’ve given us the photo of has, on top, low-voltage secondary power. Immediately below that is a coaxial CATV conductor. On this cable on the right side of the pole, the device you see is a two-port tap, the device from which CATV service to the home “drops.” Below this is something rather interesting - another CATV conductor, but one that is belongs to a two-cable (A&B) system; these are rapidly being phased out in the U.S. On this wire, on the left side of the pole is and old unused four-port tap. Immediately above this thing is what appears to be two two-port replacement taps for the old four-port. It’s also possible that those two devices are “line extenders”, or distribution amplifiers. They sometimes use the same enclosures as taps. Finally, we come down to the telco plant and the box you are concerned with, explained above. Also interesting to note on this pole are the spikes for climbing it. They are rarely used anymore (but this appears to be a quite old pole); spikes have gone by the wayside and bucket trucks are used in their stead. Another thing the spikes tell us, is that the pole is most likely owned by the telephone company. Power companies have removed these spikes from an all but a vanishingly small percentage of the poles they own. My credentials: I’m an Outside Plant Engineer for this consulting company - [www.teamsigma.com](http://www.teamsigma.com) ---
**Author:** ![UncleBeer](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)\ **Post date:** [November 7, 2002, 6:30pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/12 "2002-11-07T18:30:41Z")
Oh yeah, the clamps. Those will be difficult to spot since they’re integral to the cabinet. Another thing to note for the layman. Conductors, of any type, are not merely strung between poles. A steel, or perhaps stainless steel, strand is used and serves as the load-bearing member of the assembly. The actual conductors are then lashed to the strand. You can see this up close to the pole, especially on the power and topmost CATV wires, where they diverge from the strand. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [November 7, 2002, 8:48pm UTC](https://boards.straightdope.com/t/what-are-the-black-lumpy-things-on-power-lines/135168/13 "2002-11-07T20:48:42Z")
Unc, you sure about that? The PDF you provided us of the pole-mounted cabinet looks _much_ larger than the lumpy thing in the picture. Also, the lumpy thing in the picture isn’t pole mounted, is it?