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Comment by jmspring | Hacker News Reader

The pole numbering also helps in things like the work PG&E has to do checking for trees and other obstacles posing a risk to transmission lines. The report indicating where the work needs to be done (for instance to cut down a tree) uses the pole number as a point of reference.

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Not just utility related reporting uses the pole numbers.

My father was the volunteer emergency service coordinator (and power station operator) in the tiny town where we grew up. his use of road names + power poles ids + direction & distance was frequently complimented by the accident investigators when they came to look at shit (and later the court cases for some)

Remote areas with 10s of KMs of power line and 0 other features :|

Yes, I am intimately familiar with this as this was also part of the services that I was involved in delivering. One of the deliverables for utility clients we provided was every "fall in" or "drop in" line violation for high power transmission lines, including their "between" location in relation to adjacent poles on the corridor.

I could talk about this subject for hours so let me know if you have any other questions.

What's a typical range of amperage for a distribution line?

Most distribution transformers have a maximum rating of 200kVA. So depending on their voltage you can calculate the max amps by (200kVA / voltage). Minimum amps is a bit harder to calculate but I would make a best guess of 20% of the max 200kVA.

You can read a bit more about the calculations here[0]

[0] https://yorkcentraltechtalk.wordpress.com/2012/06/27/transfo...

Edit: noted that 200kVA is the maximum rating, not default rating.

Do the distribution transformers have "winter" ratings like the local center tapped step down transformers that feed houses? Around here it is pretty clear that Georgia Power doesn't pay much attention to the name plate ratings, winter or otherwise, when sizing and determining the number of homes per xformer.

Distribution transformers are not usually thought of as having a winter rating. On the other hand, distributions lines definitely do. Sometimes work on lines can only be done during the winter, because the load has to be shifted to lines that can only handle the increased temporary load during the winter.

There is a science and an art to sizing residential xfmrs. Generally is depends on the square footage, number of bedrooms and type of fuel used to condition the house.

Probably where GP is running into problem(like most electrical utilities) is that the use of electricity per square foot keeps going up.(caused by the increase of electrical devices in the home) So while the xfmr might have been sized correctly when installed 20-40 years ago, it is no longer sufficient. This causes problems.

Source: I was a distribution engineer for 7 years.

Thanks for the info. Day job has me using the NEC frequently, and occasionally the NESC.

But I never thought about pole xformer sizing until this house. Our 35kVA (summer) faceplate xformer services nine homes. Even though it browns, it keeps on working. They've got a lot of margin, it seems

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