# Any electrical power Dopers here? What is this on the power pole? **URL:** \ **Category:** Factual Questions\ **Created:** [April 11, 2024, 12:32am UTC](https://boards.straightdope.com/t/any-electrical-power-dopers-here-what-is-this-on-the-power-pole/1000123 "2024-04-11T00:32:02Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [April 11, 2024, 12:32am UTC](https://boards.straightdope.com/t/any-electrical-power-dopers-here-what-is-this-on-the-power-pole/1000123/1 "2024-04-11T00:32:02Z")
About every eight poles, there was one that had this arrangement of wires- one connected to each power leg, then an insulator, then all connected to (ground?): [[Album] imgur.com ![](https://i.imgur.com/DzSpdwH.jpeg?fb "imgur.com") ](https://imgur.com/a/oZuxZWU) ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [April 11, 2024, 1:28am UTC](https://boards.straightdope.com/t/any-electrical-power-dopers-here-what-is-this-on-the-power-pole/1000123/2 "2024-04-11T01:28:02Z")
Could it be a common lightning arrestor? > **[Lightning arrester](https://en.wikipedia.org/wiki/Lightning_arrester)** > > A lightning arrester (alternative spelling lightning arrestor) (also called lightning isolator) is a device, essentially an air gap between an electric wire and ground, used on electric power transmission and telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a ground terminal. When a lightning surge (or switching surge, which is very similar) travels along the powe... Can’t quite make them out from your photo… ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [April 11, 2024, 1:30am UTC](https://boards.straightdope.com/t/any-electrical-power-dopers-here-what-is-this-on-the-power-pole/1000123/3 "2024-04-11T01:30:46Z")
I think that’s possible. Sorry about the photo, we were zooming down the highway… ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [April 11, 2024, 1:17pm UTC](https://boards.straightdope.com/t/any-electrical-power-dopers-here-what-is-this-on-the-power-pole/1000123/4 "2024-04-11T13:17:54Z")
> [@DPRK](#): > > Could it be a common lightning arrestor? I’ve never seen that, but it seems like a logical setup when there isn’t a static line running above all the other conductors. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [April 11, 2024, 2:22pm UTC](https://boards.straightdope.com/t/any-electrical-power-dopers-here-what-is-this-on-the-power-pole/1000123/5 "2024-04-11T14:22:57Z")
Basically for lightning protection. Seems the term of art is _line surge arrestor_. They can protect from other faults, but lightning is the main problem. They can be complicated - internally containing a MOV to adsorb energy, and an external spark gap to let serious overvoltages get to ground. And also, in the event they fail as a short circuit, a small explosive charge that disconnects the ground connection. Not sure if the smaller one have all of this. They appear on the really big transmission lines as well, and really need to behave safely. The key idea seems to prevent lightning induced surges from getting far enough that they trip out the system. Lightning can lead to saturation of transformers, which doesn’t play nice with their operation. There is a lot of protection in the grids to avoid damage. But you similarly want to try to avoid the problem in the first place, so surge arrestors. ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [April 11, 2024, 3:41pm UTC](https://boards.straightdope.com/t/any-electrical-power-dopers-here-what-is-this-on-the-power-pole/1000123/6 "2024-04-11T15:41:05Z")
> [@Francis\_Vaughan](#): > > Seems the term of art is _line surge arrestor_. Excellent. The very last photo on [this page](http://www.arresterworks.com/resources/photo.php) appears to be basically the same thing, though wired slightly differently.