Power lines

[topnotchtree]

As a general rule, the bigger the insulators the more power. But there are always exceptions. Like doing emergency repairs the lineman will use available hardware on hand, not necessarily the proper stuff.

 

[NeTree]

While I have it in mind, alot of guys are under the impression that the black coating on some primary lines is insulation.

It's not.

It's only a weatherproofing, and is neither intended as an insulator, or to be relied upon as such.

FWIW!

 

[TheTreeSpyder]

Amen!

One more pic/collection along the Human Conductor topic; from the same source: US Dept. of Labor Corp's Urban Foresty Manual, by ACRT. When asked before about recomended books; i think we missed this book!

 

[Eagle1]

Now that is usefull stuff. Thanks

 

[Dobber]

safety in line clearing

if any of you are serious about knowing the hazards in working near energized conductors look up eusa safe practice guide and order the line clearing operations book. this is concidered the law in Ontario, you may find it very informative. unfortunatly you cant look up any rules on their web site (I guess safety is only a factor if they can make money off of the sale of books) otherwize PM me and I will look it up for you.

 

[highpoint-utd]

hm always wondered why in the us mains electric cables are overhead and not buried in the deck like here in the uk ?the only tree work carried out near live cable is on national grid pylons and national grid networks .

 

[Crofter]

Eye Opener

Something I found interesting at a safety course put on by Ontario Hydro was the fact that electrical lines can move up and down 5 or 10 feet over a short period of time due toad changes on the line. The difference in temperature due to load can change the tension that much. Where you had enough clearance in the morning could put you dangerously close later in the day. Over a certain voltage requires a continuous spotter.

Frank

 

[topnotchtree]

Underground wires are not always the best as most people think. Overhead wires run cooler,and when there is a problem it is usually easy to locate and fix.When underground wires have problems,and they do get their share of them, the faults are hard to find. And then hard to get to to fix! Besides, if all power lines were underground I would not have a job!

 

[NeTree]

That's why lines strung in the summer are deliberately left with some slack, so the line can contract in cold weather without breaking from too much tension.

The electrical resistance of the line converts power into heat. This is why energizing a line is called "heating it up" in linemans' slang.

How much the line will lengthen/shorten with varying load depends on alot of factors, such as length of span, conductor material, conductor diameter, ambient temperature and the actual load applied.

Lines will tend to lengthen with:
Higher ambient temps
Aluminum conductors
High electrical loads
Smaller diameter lines (which have a higher resistance)

...and shorten when the reverse is true.

 

[MasterBlaster]

DOYURDOODIE

Hey, this is a great thread ya'll.

Lets archive it properly by rating it.

Hmmmmm?