Yep, high power lines can be dangerous

[woody]

Yesterday in Amsterdam a (power) company dug up and damaged a grid cable that was still carrying power. This lead to an overload in another cable, elsewhere in the city. That cable (or more likely a weld) exploded spectacularly as shown on this security camera footage:

https://nos.nl/video/2221492

Two people had to be treated in hospital for minor burns. Still, they were lucky, as was the pedestrian that passed over the already lifting paving.

[Ampera]

Video doesn't appear to load for me, Chrome on NT 2016, everything most recent.

However, water is wet.

[IanB]

That's a pretty spectacular explosion. And I don't think it needs to be a grid cable to do that either. In that location it's more likely to be a regular buried medium voltage distribution cable.

[T3sl4co1l]

Yikes, literally hell opening up!

Tim

[Brumby]

Quite a flame from nowhere!

[ucanel]

Video doesn't appear to load for me, Chrome on NT 2016, everything most recent.

However, water is wet.

Same issue unless without using proxy,
so I found the same video on youtube:

[raptor1956]

Some years ago a couple of Verizon workers, who were on strike at that time, decided to cut a trunk line but instead cut into a 13KV line.  The guys died almost instantly and the woman, his girlfriend, died after being burned by plasma.  So, be careful what you cut into...


Brian

[Brumby]

I once knew a guy who worked for our local electricity supplier.  Came in to work one morning to find an unusual bit of activity ... three copper thieves picked the wrong cable.

[jordanp123]

We had a copper thief come in and steal some copper from one of our substations several years back. 69KV-12.47KV, it was a Delta-Wye connection and they cut the Wye connection neutral, along with almost every ground bond we had. This station served residential loads so a unbalanced connection was the norm. We later came to call this guy "Houdini" as we found no *ahem* lost members, and after calling around to the local hospitals no one who came in with severe burns. Only thing we found was bolt cutters that you would buy at the local hardware store with huge burn holes in the mouth.

[Galenbo]

That doesn't look at all like the 400V and 11KV electric fires I saw.
There's no copper spitting, the velocity and fire distribution is different.

Looks more like a mid-pressure gas fire.

[Beamin]

Yesterday in Amsterdam a (power) company dug up and damaged a grid cable that was still carrying power. This lead to an overload in another cable, elsewhere in the city. That cable (or more likely a weld) exploded spectacularly as shown on this security camera footage:

https://nos.nl/video/2221492

Two people had to be treated in hospital for minor burns. Still, they were lucky, as was the pedestrian that passed over the already lifting paving.

It says I need "adventures in social media cookies" to watch the video? 

[Beamin]

That doesn't look at all like the 400V and 11KV electric fires I saw.
There's no copper spitting, the velocity and fire distribution is different.

Looks more like a mid-pressure gas fire.

I thought the same thing because it was so orange. Maybe it vaporized the rubber and flashed over when it hit air. The first smoke is white like unburned vapor.

[mikeselectricstuff]

That doesn't look at all like the 400V and 11KV electric fires I saw.
There's no copper spitting, the velocity and fire distribution is different.

Looks more like a mid-pressure gas fire.

Oil insulated cable ?

[G7PSK]

Even a 240 volt power line can do a lot of damage. They were laying a new water pipe outside my mother in laws house to a new house next door and the contractor managed to cut the 240 volt power line with an JCB. The arc cut a big chunk out of the bucket asa well as lifting the bround all the way back to a pole 30 feet away.

[Lord of nothing]

30 feet away.

even in the UK the have the Metric System.  Maybe you heard about? 

Thats why I try to wear flame Resistant Cloth! You never know when someone do a stupid thing! 

[IanB]

30 feet away.

even in the UK the have the Metric System.  Maybe you heard about? 

Thats why I try to wear flame Resistant Cloth! You never know when someone do a stupid thing! 

Sorry, but 30 feet is a metric. So it's definitely part of a metric system.

[Jeroen3]

That doesn't look at all like the 400V and 11KV electric fires I saw.
There's no copper spitting, the velocity and fire distribution is different.

Looks more like a mid-pressure gas fire.

Oil insulated cable ?

I read somewhere it was some type of sleeve that occasionally fails this spectacularly. It should have been replaced ages ago though.
But I do not know if this source was reliable, since I cannot find it anymore.

[IanB]

We have to think how many megawatts one of those distribution cables can deliver in a fault condition before the circuit is interrupted. If the fault current is hundreds (thousands?) of amps at tens of kilovolts that's a lot of energy to be dissipated. If it vaporizes the copper and the surrounding insulation that will produce a high pressure, flammable vapor cloud that has to go somewhere. At such voltages there is practically no resistance to limit the current.

[Ampera]

30 feet away.

even in the UK the have the Metric System.  Maybe you heard about? 

Thats why I try to wear flame Resistant Cloth! You never know when someone do a stupid thing! 

Sorry, but 30 feet is a metric. So it's definitely part of a metric system.

I'm sorry Europangeans, it's 10 yards, and yards are identical in every way shape and form (except for where they're not) to meters, or metres, or meaters.

[T3sl4co1l]

I'm sorry Europangeans, it's 10 yards, and yards are identical in every way shape and form (except for where they're not) to meters, or metres, or meaters.

I prefer meateaters.

Tim

[Lord of nothing]

30 feet away.

even in the UK the have the Metric System.  Maybe you heard about? 

Thats why I try to wear flame Resistant Cloth! You never know when someone do a stupid thing! 

Sorry, but 30 feet is a metric. So it's definitely part of a metric system.

I'm sorry Europangeans, it's 10 yards, and yards are identical in every way shape and form (except for where they're not) to meters, or metres, or meaters.

Wikipedia say: 1 yard = 3 feet = 36 inches = 0,9144 Meter

[The Soulman]

30 feet away.

even in the UK the have the Metric System.  Maybe you heard about? 

Thats why I try to wear flame Resistant Cloth! You never know when someone do a stupid thing! 

Sorry, but 30 feet is a metric. So it's definitely part of a metric system.

I'm sorry Europangeans, it's 10 yards, and yards are identical in every way shape and form (except for where they're not) to meters, or metres, or meaters.

Nope, one yard equals three feet equals 91,44 centimeters, the hard part is to actually convert that to meters by dividing by 100.
So 91,44/100=0,9144 meters.
I understand this metric stuff is way to advanced for people on the other side of the lake. 

[IanB]

Wikipedia say: 1 yard = 3 feet = 36 inches = 0,9144 Meter

Well, there you are then. You are comparing a nice round number of "1" with a complicated decimal of "0.9144". It's obvious which one is neater and more convenient to work with 

[Ampera]

What you guys forget is I'm smart enough to operate in both systems, while all y'all are too stupid to use our intricate and complicated units.

Love from the US!

[Marco]

What you guys forget is I'm smart enough to operate in both systems, while all y'all are too stupid to use our intricate and complicated units.

You're only human ... genius level IQ people have screwed up due to imperial/metric/nautical/statute conversions.

Wish post WW2 US military dominance hadn't screwed us over with your nautical miles and knot bullshit.

[Ampera]

What you guys forget is I'm smart enough to operate in both systems, while all y'all are too stupid to use our intricate and complicated units.

You're only human ... genius level IQ people have screwed up due to imperial/metric/nautical/statute conversions.

Wish post WW2 US military dominance hadn't screwed us over with your nautical miles and knot bullshit.

You could have at least given us the good pyrex, not let some idiots make this blue tinted tempered glass stupidity.

Units are units. Truth be told, the US doesn't use our customary units too much anymore. Our roads, cakes, and cars are measured in US customary, with the most technical application being construction. Pretty much everything else is SI.

[Vtile]

30 feet away.

even in the UK the have the Metric System.  Maybe you heard about? 

Thats why I try to wear flame Resistant Cloth! You never know when someone do a stupid thing! 

Sorry, but 30 feet is a metric. So it's definitely part of a metric system.

I'm sorry Europangeans, it's 10 yards, and yards are identical in every way shape and form (except for where they're not) to meters, or metres, or meaters.

Nope, one yard equals three feet equals 91,44 centimeters, the hard part is to actually convert that to meters by dividing by 100.
So 91,44/100=0,9144 meters.
I understand this metric stuff is way to advanced for people on the other side of the lake. 

since when? Meter is the base unit and the US customary units are now defined from SI base units. So the correct is:
yard (yd) .............................................................. meter (m) .................................................... 9.144 E?01
Source: Guide for the
Use of the International
System of Units (SI)
 NIST https://physics.nist.gov/cuu/pdf/sp811.pdf

 

[Galenbo]

That doesn't look at all like the 400V and 11KV electric fires I saw.
There's no copper spitting, the velocity and fire distribution is different.

Looks more like a mid-pressure gas fire.

Oil insulated cable ?

Never heard of that, never saw that, thanks for the remark, I'll look it up.

Here in Belgium power lines and gas often are close to eatchother, it can still be a short-circuit that induced a gas fire.
In the netherlands they speculate about an earth/fase short.

https://www.circuitsonline.net/forum/view/140314

[Iwanushka]

That doesn't look at all like the 400V and 11KV electric fires I saw.
There's no copper spitting, the velocity and fire distribution is different.

Looks more like a mid-pressure gas fire.

Oil insulated cable ?

Never heard of that, never saw that, thanks for the remark, I'll look it up.

Here in Belgium power lines and gas often are close to eatchother, it can still be a short-circuit that induced a gas fire.
In the netherlands they speculate about an earth/fase short.

https://www.circuitsonline.net/forum/view/140314

Good old cables had paper, oil and lead "shielding"

[jmelson]

[Truth be told, the US doesn't use our customary units too much anymore. Our roads, cakes, and cars are measured in US customary, with the most technical application being construction. Pretty much everything else is SI.

HUH?  CARS?  Everything on our cars has been metric for 30 years, EXCEPT the wheel lug nuts and the oil drain plug.  (And, I think a bunch of makers are coming over on those items, too.)

Jon

[Brumby]

While off-topic, following on from the units discussion ... the ones that get me have nothing to do with the metric system.  It's the US/imperial gallon and ton.

At least with the metric system, there is only one definition of anything.

[Ampera]

[Truth be told, the US doesn't use our customary units too much anymore. Our roads, cakes, and cars are measured in US customary, with the most technical application being construction. Pretty much everything else is SI.

HUH?  CARS?  Everything on our cars has been metric for 30 years, EXCEPT the wheel lug nuts and the oil drain plug.  (And, I think a bunch of makers are coming over on those items, too.)

Jon

I mean the use of cars, not the construction. Probably should have said gas pumps instead, but roads, speeds, and almost anything outside of servicing is customary. Makes sense, though, since the automotive industry is a heavily internationalized one.

[Beamin]

30 feet away.

even in the UK the have the Metric System.  Maybe you heard about? 

Thats why I try to wear flame Resistant Cloth! You never know when someone do a stupid thing! 

Sorry, but 30 feet is a metric. So it's definitely part of a metric system.

I'm sorry Europangeans, it's 10 yards, and yards are identical in every way shape and form (except for where they're not) to meters, or metres, or meaters.

Nope, one yard equals three feet equals 91,44 centimeters, the hard part is to actually convert that to meters by dividing by 100.
So 91,44/100=0,9144 meters.
I understand this metric stuff is way to advanced for people on the other side of the lake. 

Have you not seen American TV documentaries? Everything is measured in football. The wire was 1/10 of a football field long. The circumference of the earth is 300000 football field around. The speed of light in an inflated football is 78236817624 football fields per second. Your wifi runs at 2.4 pico half times per second.

[Lord of nothing]

  the same here in Austria the say often the Size is X from an Soccer Field.   

[Gromitt]

the same here in Austria the say often the Size is X from an Soccer Field.   

I think you mean 'real football field'   

[Lord of nothing]

sure. I just hate the "sport". 

[Ampera]

I've never seen a game of US football, also known as rugby for wimps.

I've never seen a game of rugby either.

I don't usually watch sports, but I do like a good baseball or soccer match, especially if it's live. I watched the 2016 Cubs world series game 7, and that was a game to never forget. It's almost as if the planet itself was doing all it could to make the situation more epic.

[Zucca]

Why not the fuse but the buried cable?
As I understood you invest money in a fuse to save the expensive cable and the effort do dig it up in case something goes wrong, in this case that line had no protection.

Am I wrong?

[IanB]

Why not the fuse but the buried cable?
As I understood you invest money in a fuse to save the expensive cable and the effort do dig it up in case something goes wrong, in this case that line had no protection.

Am I wrong?

Most likely the cable had some protective devices. However, it must be remembered that such a cable is designed to deliver large amounts of power from point A to point B. The cable is therefore also able to deliver large amounts of power into a fault. The protective devices cannot necessarily tell the difference between a normal load and a fault situation.

[Zucca]

The protective devices cannot necessarily tell the difference between a normal load and a fault situation.

well in my eyes that protective device is not well designed and it is not doing his job.

[jmelson]

The protective devices cannot necessarily tell the difference between a normal load and a fault situation.

well in my eyes that protective device is not well designed and it is not doing his job.

Low voltage systems (up to 480 V or so) will tend to weld to a dead short, and blow the fuse promptly.  High voltage systems (and really, here, the power systems pros will call this medium voltage, 4000 - 14000 V) tend to arc and not weld to a dead short.  We had a feeder at work right out of the transformer short out.  All the lights on campus went out, and there was this huge arc burning underground toward the transformer.  They had to wait for a guy from the electric utility to come out in a truck to turn off the HV into the transformer.  Then, they just cut off the wires to the failed feeder with a hacksaw and turned it back on.  We had 4 parallel feeders that were connected together at each end (transformer and switchgear).  Due to induced currents in the conduit, they have to run all 3 phases plus neutral in each conduit, so the induced current nulls out.

Jon

[SeanB]

Well, the blast is typical of an old paper insulated cable failing, probably due to water ingress from a corroded lead sheath on a joint, or the cast iron sheath corroded a pinhole. They can and do excavate themselves in the half second or so it takes for the MV circuit breaker to trip out, as those are designed to have a slight delay so they do not trip out when you power on a cold load after either a power failure or after it has tripped out due to a fault. Cable and switchgear is designed to survive the heating longer than it takes to trip out again, to isolate the fault, not to limit arc damage.

I have seen them dig a hole in the road 6m deep, as that is how deep the join was when the 33kV line failed early one morning. road was closed, seeing as there was no more lane either way, and the pavements were somewhat damaged as well by the blast.

Funny thing is 11kV cabling is a lot faster on protection, the guy with the pickaxe from Digotel (the colloquial name for the fibre layers, who are capable of finding every water pipe, cable and phone line in the road it seems) just had a wake up call, and a 1cm bite in the tip of the pick axe he put through the joint.

[mikeselectricstuff]

The protective devices cannot necessarily tell the difference between a normal load and a fault situation.

well in my eyes that protective device is not well designed and it is not doing his job.

So how do you tell the difference between, say, a resistive load drawing 50kW and a resistive fault ( due to carbonised burnt stuff) drawing 50kW?

[T3sl4co1l]

So how do you tell the difference between, say, a resistive load drawing 50kW and a resistive fault ( due to carbonised burnt stuff) drawing 50kW?

There are arc fault detectors, which monitor for the high frequency, noisy content generated by the latter.  I don't know how widespread their deployment is, though.

Tim

[mikeselectricstuff]

So how do you tell the difference between, say, a resistive load drawing 50kW and a resistive fault ( due to carbonised burnt stuff) drawing 50kW?

There are arc fault detectors, which monitor for the high frequency, noisy content generated by the latter.  I don't know how widespread their deployment is, though.

Tim

High voltage arcs are detectable fairly easily due to the HF content from the sparks, but I'd expect that at lower voltages a "cable on fire" type fault looks more like a resistive load, as the resistive path means you're not going to get much sparking after the initial failure.

[Zucca]

So how do you tell the difference between, say, a resistive load drawing 50kW and a resistive fault ( due to carbonised burnt stuff) drawing 50kW?

You can't, the same will happen in an apartment if the failure will drawn 14,9A with a 15A protection thing.

[Beamin]

Why not the fuse but the buried cable?
As I understood you invest money in a fuse to save the expensive cable and the effort do dig it up in case something goes wrong, in this case that line had no protection.

Am I wrong?

There is a lot more to it then that. But say that was the solution; a lot of privately owned companies would rather gamble taking the risk; pay for damage and law suits then pay for upfront costs. A corporation only exists 3 months at a time. Quarter to quarter. For example many companies know that raising the minimum wage would in the mid to long term equal higher profits: they have mathematicians and actuaries that are paid a lot of money to figure this out they are way too smart not to know this. But that would mean a 100% chance of losing profits this quarter for a 90% chance of more profit in 6 months to a year. No company wants to front the cost because of the way a corporation is obligated to its shareholders that can leave in seconds due to the stock market. Crazy.

Also I realized if something has an obvious answer but no one is doing it most of the time it's because I don't know all the details.