132kV Power Supply - safety issue

Don,

the pylons you describe carry 400kV not 132kV. You are quite safe when it is raining you will not become part of a circuit to earth. 400kv can not strike beyond 3.2 metres.

I walk under 400kV cables everyday a lot closer than the pylons as I work on a power station.

400kV - phew - glad I thought they were only 132kV.

Also glad to know that even in a downpour, 3.2m or more is safe. I shall enjoy tomorrow's walk, no matter how loud any power cables are humming.

Many thanks.

Cheers

Don

One thing that is fun to try is to see if you can feel the induced voltage in the ground from the HV lines. Go with a friend, stand about 1.5m apart under the lines, midway between two towers (barefeet is likely best). Reach out and touch your friend's ear. Often you can feel/hear an AC buzzing/vibration. Spooky. Try standing both across and in line with the direction of the wires. Doesn't need fog or rain as it is induction, not transmission that is putting the voltage into the ground.

quote:

Go with a friend, stand about 1.5m apart under the lines, midway between two towers (barefeet is likely best). Reach out and touch your friend's ear.

Winky,

You could get Sectiond under the Mental Health Act in the UK for less than this!!

Cheers

Don

quote:

Originally posted by Don Atkinson:

quote:

Go with a friend, stand about 1.5m apart under the lines, midway between two towers (barefeet is likely best). Reach out and touch your friend's ear.

Winky,

You could get Sectiond under the Mental Health Act in the UK for less than this!!

Cheers

Don

Well yes, there is that...

I have a 400kv pylon line that crosses one of my walks (horrible blots on the landscape)
It has the usual 3 phases per side but each of the phase lines has 4 cables, so I guess it is carrying a bit of power.
The pylon close to the path has one insulator that is always buzzing, sounds like its arching across something. Its the same in duct dry summer or in the 200yd fogs of the last few days. Been that way for at least 5 years so I guess its OK & nothing to worry about

The thing I notice is that the local & quite large rook & crow population who nest & perch all over the nearby trees & hedgerows keep well clear of the trees around the pylon.

quote:

The thing I notice is that the local & quite large rook & crow population who nest & perch all over the nearby trees & hedgerows keep well clear of the trees around the pylon.

Looks like they can measure 3.2m to within a gnat's whisker...

Cheers

Don

quote:

Originally posted by Mike-B:
I have a 400kv pylon line that crosses one of my walks (horrible blots on the landscape)
.

Yes. When I lived in Bristol, I was often dismayed by the intrusion of HV power-lines into the landscape. They seemed incredibly frequent in that area. Not sure why.

quote:

I have a 400kv pylon line that crosses one of my walks (horrible blots on the landscape)

I agree with both yourself and Winky but....

and here is my dilema,

When I am flying from (say) Kamloops to Penticton, or from Vernon to Nelson, those tracks across the landscape made by powerlines, make very good visual navigation features!!

But in truth, they are an eyesore. I have a vague recollection that equivalent capacity underground transmission cables could be ten times as expensive to provide. (perhaps 10x is a bit of an exageration?)

Cheers

Don

quote:

Originally posted by Don Atkinson:

quote:

I have a 400kv pylon line that crosses one of my walks (horrible blots on the landscape)

I agree with both yourself and Winky but....

and here is my dilema,

When I am flying from (say) Kamloops to Penticton, or from Vernon to Nelson, those tracks across the landscape made by powerlines, make very good visual navigation features!!

But in truth, they are an eyesore. I have a vague recollection that equivalent capacity underground transmission cables could be ten times as expensive to provide. (perhaps 10x is a bit of an exageration?)

Cheers

Don

Yep, an eyesore. They are ugly slashes across the BC wilderness as well as the Cotswolds. But they serve a purpose. It is one of the many compromises that we, as a society are prepared to accept for our lifestyle, toys, convenience and well-being. As we become materially wealthier, and/or change our values, we may one-day think it worth the cost of removing them.

quote:

Yep, an eyesore. They are ugly slashes across the BC wilderness as well as the Cotswolds. But they serve a purpose.

An alternative would mean actually digging a large trench across BC or the Cotswolds etc, at least until they can start to beam the power to our houses.

quote:

Originally posted by BigH47:

quote:

Yep, an eyesore. They are ugly slashes across the BC wilderness as well as the Cotswolds. But they serve a purpose.

An alternative would mean actually digging a large trench across BC or the Cotswolds etc, at least until they can start to beam the power to our houses.

Yeah, but they'd fill it back in. It would be effectively invisible across farmland, but I imagine that they would keep the trees cleared from above it in BC forests. The clearing would remain, but the pylons and wires would be gone (from sight).

The choices that we as a society could make would be to live more simply. Reduce our electricity consumption to the point where these things would not continue to breed, or perhaps even take some down. We could also choose to reduce our population, thus removing the need for so many of these things.

It is worth noting that the current system of pylons and cables cutting straight across the landscape is absolutely the cheapest option available. We have chosen not to spend one extra cent on making these things less visually and environmentally offensive.

I'm with you, I'm not advocating pylons, it's been the go to solution, and I don't see it changing any time soon.

It would be interesting to see the relative costs of trenching vs pylons over a 40 or so year period including maintenance costs.

Unfortunately long term projects are funded with short term financials.

Perhaps Iron Cobra could provide some indicative costs?

The cost of overhead transmission is only a part of the whole electricity generation/transmission system. So I guess life-cycle capital costs and operating costs for the complete system needs to be taken into account when looking at the differential cost of O/H v Underground transmission.

Cheers

Don

As I started this ... sorry ... some facts

I just dug out some of my old reference books & scurfed the interwebbything on the pro/con of overhead vs underground with 400kv & 270kv EHV

Quote(s) (edited down to reduce word count)
For reliability, cost, construction impacts and land use, overhead lines are preferable to underground cables.
Underground cable offer benefits only in terms of reduced visual impact
Underground can significantly impact sensitive and protected ecological & archaeological areas, they additionally restrict the use of land in the long term.

Using modern cable techniques it costs approximately 12 to 17 times as much to install a 400kV underground cable -vs- an equivalent overhead line.

Major element of cost differential is the cable itself.
These voltages need special insulation & underground cables have traditionally used high pressure fluid (oil)
The use of fluid filled cable is diminishing and XLPE cables are now being introduced (cross linked polyethylene)

Additionally underground EHV cables must be buried in tunnels, not filled in trenches
132kV and below XLPE cable can be buried directly in the ground.
275kV & 400kV XLPE cable must be carried in tunnels but this is subject to ongoing review

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