I see this setup all over my neighborhood and am curious about one of the components. The houses on the outer edge of the neighborhood seem to get their electricity by tapping into one of the phases of the power line that's set up right behind the backyards.

I can identify the insulators that keep the conducting line secure and the safety fuse/switch, but the conductor then goes into and out of a vertical cylindrical component just before it's sheathed in insulation and goes into the ground. What could this be?

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    \$\begingroup\$ I would say that is most likely a spark gap for overvoltage/lightning protection \$\endgroup\$
    – KristoferA
    Commented Feb 26, 2023 at 5:20

2 Answers 2


That is a surge arrester applied in shunt to the cable connection. It serves to limit voltage surges that may come in from the overhead line so that they go to ground at the pole rather than going on to the cable and possibly damaging the cable insulation.

This application is called a "riser pole arrester", and information about this application of surge arresters can be found here, with many more resources to learn all about arresters as they are applied in the power system available from ArresterWorks.


This would be a lightning surge, arrester made of an array of zinc oxide discs with insulation on the outside. These limit the current to protect the grid. It looks like there is a signal wire out of the top which would be a reactance current sense divider to something like 1000 to 1 ratio going to down the pole cable with an insulated feed to some type of data collection device on the pole for monitoring lightning strikes on the grid.

The top 1 of 4 wires attracts most of the lightning directly to earth while this arrestor is for next wire down which is the top of 3 phase grid wires only. Thus this has dual lightning protection and there may be more details not shown.


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