Overhead Power Lines Dangerous To Life and Property

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kwired

Electron manager
Location
NE Nebraska
Hopefully being the key word..

you know where an additional circuit is going to be needed or where potential housing developments or industrial will be in 10 or 20 years?
That has to be dealt with even when everything is overhead.

I have buried spare service raceways before on commercial/industrial and have pulled conductors through them at times when more service capacity became needed. That may be a little trickier for utilities to determine where they may need to do similar with a MV distribution system though.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
That has to be dealt with even when everything is overhead.

I have buried spare service raceways before on commercial/industrial and have pulled conductors through them at times when more service capacity became needed. That may be a little trickier for utilities to determine where they may need to do similar with a MV distribution system though.
Yes, but with overhead adding conductors or another circuit the cost is nothing compared to UG
 

kwired

Electron manager
Location
NE Nebraska
Yes, but with overhead adding conductors or another circuit the cost is nothing compared to UG
True, but a spare raceway where you know someday you might need it saves excavation expenses or even demolition/and replacement of pavement, landscaping, etc. Like I said this maybe not so easy to know were to do so with general MV distribution as it is for service runs to individual customers though.

Once you have added enough load and need to bring a new transmission line and sub station to an area you are sort of starting from scratch with the transmission line anyway, which I don't think there are many places that bury transmission level lines anyway. I only know of one such place near me and that is only about a one mile stretch of line because it is next to an airport. It starts at a sub station and runs past where air port needs the above ground clearances then is overhead beyond that.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Yes, but with overhead adding conductors or another circuit the cost is nothing compared to UG
For UG, the only way to add capacity is re-trench, add additional raceways in a duct bank for future installation, or over-size raceways to pull larger conductors in the future. I'm guessing re-trenching is the most expensive option, but I have no idea what the additional challenges might be for other options. Looking to learn things.
 

kwired

Electron manager
Location
NE Nebraska
For UG, the only way to add capacity is re-trench, add additional raceways in a duct bank for future installation, or over-size raceways to pull larger conductors in the future. I'm guessing re-trenching is the most expensive option, but I have no idea what the additional challenges might be for other options. Looking to learn things.
I could see a spare or oversized raceway in strategic locations in primarily residential/light commercial neighborhoods would allow to increase capacity to select spots where you can then divide it up accordingly. But should some larger industrial loading come along you very well bringing new or updated ability somewhere near the location regardless.
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
What are the ranges for what's considered MV, distribution, and transmission. I am clueless. If I had to guess my guesses are

7.2kv to 26kv ???? For MV


Transmission - 250k +?????

Help me out
 

kwired

Electron manager
Location
NE Nebraska
What are the ranges for what's considered MV, distribution, and transmission. I am clueless. If I had to guess my guesses are

7.2kv to 26kv ???? For MV


Transmission - 250k +?????

Help me out
local distribution is typically in the MV ranges. Don't know what the industry calls the ceiling for this but about 15k or less is pretty common.

Some "transmission lines" are only about 35k, but that may be considered more the upper end of local distribution in some cases.
 

kwired

Electron manager
Location
NE Nebraska
What do they call over 230 kV? We have a transmission line at 345 kV here in Michigan.
Ludricous voltage? :cool:

Newer 345kV line running to a new sub feeding a pretty large region of the state that was previously somewhat undersupplied for today's needs. that sub is only a few miles from where I live. Has nothing but 115 kV lines leaving it that were all re-routed to the new sub.
 

paulengr

Senior Member
For UG, the only way to add capacity is re-trench, add additional raceways in a duct bank for future installation, or over-size raceways to pull larger conductors in the future. I'm guessing re-trenching is the most expensive option, but I have no idea what the additional challenges might be for other options. Looking to learn things.

How do you do voltage class upgrades such as 13.5 kV to 35.4 or 69? Sometimes line upgrades are easy but with UG you get to redo it all.
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
What do they call over 230 kV? We have a transmission line at 345 kV here in Michigan.
We have a couple of major ones running thru here of 750kv just to send power to NYC, and a 500kv. Not sure of the process that is happening but you can walk under it on humid days and hear it buzzing. I've seen Maintenance crews here riding a gondola along the wires inspecting the cables, definitely not something I'd want to do. I assume though if you were to ground out on that much you'd never know it, you're gone almost instantly. Also seen these insane guys:
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
We have a couple of major ones running thru here of 750kv just to send power to NYC, and a 500kv. Not sure of the process that is happening but you can walk under it on humid days and hear it buzzing. I've seen Maintenance crews here riding a gondola along the wires inspecting the cables, definitely not something I'd want to do. I assume though if you were to ground out on that much you'd never know it, you're gone almost instantly. Also seen these insane guys:
His brother is probably one of those freaks who climbs 500 foot radio towers to change the bulb for the warning light.
 

paulengr

Senior Member
We have a couple of major ones running thru here of 750kv just to send power to NYC, and a 500kv. Not sure of the process that is happening but you can walk under it on humid days and hear it buzzing. I've seen Maintenance crews here riding a gondola along the wires inspecting the cables, definitely not something I'd want to do. I assume though if you were to ground out on that much you'd never know it, you're gone almost instantly. Also seen these insane guys:

That’s bare hands live line work.

You wear a chain mail (metal) suit. When the helicopter gets close you ground it to the line then just attach a chair and climb from one to the other. Or use an insulated platform/man lift from the ground insulated for the voltage. Very useful for 115 kV or higher but starting to be popular even down to 69 kV.

Like a bird on a wire, the “bare hands” (not technically true) worker is the same voltage as the cable. From that position the ground is dangerous to a degree. But with the chain mail none of it would go through them.

There are concerns about health effects but so far no long term issues have occurred.
 

kwired

Electron manager
Location
NE Nebraska
We have a couple of major ones running thru here of 750kv just to send power to NYC, and a 500kv. Not sure of the process that is happening but you can walk under it on humid days and hear it buzzing. I've seen Maintenance crews here riding a gondola along the wires inspecting the cables, definitely not something I'd want to do. I assume though if you were to ground out on that much you'd never know it, you're gone almost instantly. Also seen these insane guys:
What are these guys doing other than maybe getting a close look at what condition the conductor may be in?

Would think you don't get too close to the towers that could put potential across you. Might get close enough to insulators to see some things that may need attention soon, but you probably not getting close enough to touch them.

I think such line inspections is switching over to being done via drones in many places.
 

retirede

Senior Member
Location
Illinois
I saw where PG&E just announced that they plan to convert 10,000 miles of transmission line to underground, primarily to mitigate fire risk. The cost is estimated to be “in the tens of billions.”
To put that in perspective, that’s only about 10% of their above-ground system. They will convert about 70 miles this year. The article I read was lacking specifics about how they will get the resources (manpower and financial) to accomplish this.
 

kwired

Electron manager
Location
NE Nebraska
I saw where PG&E just announced that they plan to convert 10,000 miles of transmission line to underground, primarily to mitigate fire risk. The cost is estimated to be “in the tens of billions.”
To put that in perspective, that’s only about 10% of their above-ground system. They will convert about 70 miles this year. The article I read was lacking specifics about how they will get the resources (manpower and financial) to accomplish this.
How about better maintenance of what is there, as well as better maintaining of combustible debris on the right of ways for those lines so that when sparks do fall from equipment there is lesser chance of starting a fire?

Fires is a natural thing out there, but man has tried to stop them and allows a large accumulation of tinder to develop so when a fire does occur it is a big fire.
 
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