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Our electricity grid is connected to France, Holland and Ireland. Great big fat juicy cables under the sea, and they are all HVDC (High Voltage Direct current).

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John accepts my humour,,the last 4 years i've tried to take the Mick,,and he's completly ignored me,,bless him,,he probably thinks the same about me going on about 'customer service'          this is

I just plug it in and if it goes bang or doesn't work, I go into the garden and shout "David!" He's my next door neighbour and an electrician! 

We didn't use fuses on underground HV circuits Brew, circuit breakers, mostly vacuum interrupters or "air" type breakers charged with inert gas like Sulphur Hexafloride. All circuits had heavy sensiti

As of 01:40 (today) France is supplying just over 8%. Holland just over 4% and Ireland just over 0,5% of the total load on the UK grid.

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Not so bad in contracting Dave, theory goes out the window to practice and rules, in mining, the equipment is complicated and you need the theory, and rules were Acts of Parliament. We had sensitive earth leakage years before you contracting lot had ever heard of it, plus all sorts only used in mining equipment. AND Voltages??? Shoot! 11Kv, 6.6Kv, 3.3Kv, 1.1Kv, 550v, 240V, 110v,15vac,12Vdc,24Vac, then surface 66Kv at the switch yard. 11Kv scared the bejasus out of me, when I was a leading hand, I always took one of my electricians with me if I had a job on anything fed with 11Kv, and it was check, check and check again on isolation, and then the big screwdriver test.

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Jill, I had a miner call me once, he said his machine went bang, and lots of smoke was coming out the control chamber, when I opened the door, all there was were bits of what once were parts, thick soot all around the walls of the chamber and lots of smoke.

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Depends where and what the gas is, methane has no smell, no taste, but by God it makes a mess when it reaches 5% in the air....Then there is Blackdamp, knocks you out for good if there's enough of it!  (lack of oxygen, usually a mix of nitrogen and CO2) then there's whitedamp, CO, deadlier than anything.

I think I'll stay with electricity..

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The only nasty bit was stripping everything out, washing the chamber out with solvent, and getting the carbon out of our hands at the end of the shift.

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So not as nasty as cleaning after someone tried to steal the bus-bars from Cotgrave Primary - whilst it was still alive at 33kV.

It didn't go well for them.

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Automatic execution eh Brew?  Just for a bit of copper.  I would never cheer anybody's death, but they sure asked for it.

 

I'm with John NBL. I'd much rather work around electricity than gas.  Gas can go with such an 'Orrible boom just from a tiny spark.

 

You are right John, Theory is not so critical in contracting.  We are mostly working with a limited range of voltages.  The code is pretty straight forward.  Motors of various types come with all the info on the rating plate.  Main concerns tend to be grounding and public safety.  It was starting to get more interesting with programmable logic, rather than relay logic in industrial, but that was about the time I retired from the trade.

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They put the smell in our methane just the same as they did with towns gas and as I have never worked in a mine I would meet white and black damp. CO can be nasty but is very rarely met on the surface, I have only been affected once when I was a young apprentice, but the fitter realised what was happening and got me on oxygen sharpish.

 

Did hear a story once about a gas company overseas who decided to make their methane smell pleasant, a bit like air freshener trouble was no one reported gas escapes, soon changed when things started to go bang.

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You'd think not using a pleasant scented smell would be common sense, but I guess that died a few years ago.  You can almost imagine it.  What's that you're wearing, darlin'.?  Evening in Paris.  Lovely, have a cigarette.  The pieces might land in Paris.

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Brew, your 33Kv reminds me when I was made up to leading hand lecko at one of the pits I worked at. Engineer was walking me around everything, giving me keys and a safety walk through, as I'd be involved with a lot more being in charge. Last visit was the colliery switchyard, gave me the keys and we entered the control room, with all it's tap changing gear, then out into the fenced yard. John, he said, if you come out here for ANY reason, STAY in the marked pathways, DO NOT, under any circumstances stray from them with power on, there's 66Kv on almost everything out here, and it can jump quite a distance.

First and only time I went in there, I hate high voltage, it's so unpredictable.

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In some ways HV is safer than LV. The protection breakers for HV are very sensitive and really fast. LV on the other hand has quite coarse protection via fuses and will carry quite a large overload for a long time before they let go.

The safe approach distance for 132kV is around 5m and for 66 its 4. If the hair on your arms and the nape of your neck start to rise you might want to get the hell outa Dodge pretty pronto regardless of how far away you are.

Protection is all academic if like those unfortunates you're on the supply side and not the load.

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Those HV breakers seem to work quickly around here.  When we have one of our frequent lightning storms the power is on and off like crazy.  I end up unplugging the 'frig, freezer, and air conditioner, because it is really hard on the compressors.  They go off and then try to restart under pressure, so the thermal trip goes off.  By the time they come on the power is blinking again.  I've never lived in such a bad place for this problem.  You might as well flip the main breaker off and wait it out.

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True enough NB. I've seen all sorts in my time. Everything from nails, kitchen foil, bell wire and even a broken portable radio aerial.

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It's crazy.  When I was contracting I went to a day care centre where an  'electrician'. Had told the lady he'd installed a  100 amp service for her and charged big bucks too.  She had to call an inspector because of kids safety.  The inspector found he had wrapped the existing fuses with tinfoil.  That's where I came in because the inspector had given her my name as one of the contractors they knew.  I wouldn't touch it with a ten foot pole as the whole place needed re-wiring.  I saw the inspector a few weeks later and asked him who took the job.  He just said. "Be glad you didn't.  There's a lawsuit going on over that.  The guy that got it priced low to get it then tried to charge her more."  Some jobs just ain't worth it.

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We didn't use fuses on underground HV circuits Brew, circuit breakers, mostly vacuum interrupters or "air" type breakers charged with inert gas like Sulphur Hexafloride. All circuits had heavy sensitive protection due to the atmosphere being a hazard, ie chance of methane or worse coal dust. It's been found coal dust can be ignited by a cable blow out. A fault has to be isolated as quickly as possible, usually half a cycle or faster.

The 11Kv breakers feeding the underground workings were very large trucks house the OCB's, The only time I saw them trip was during lightning storms that took out the remote diode protecting the main ventilation fan. NSW law required power to be tripped should the main fan trip.

I got a call one night, one of my lads had been burned, he'd got a planned maintenance exam on the sec side of a transformer, 1.1Kv end. Note, we were forbidden to expose live conductors to the air by law, not rules, but law. Although a standard enclosure in a none hazardous zone, it was still law.

I had to follow the book, fence the area off, make an inspection, collect evidence for a full report, make sure nothing was disturbed, other than lock off the circuit breaker and danger tag it. I spent about a couple of hours on the sight with a district Deputy, who also had to write his accident report.

I filed my report in triplicate, just facts, no judgements or how I thought the accident occurred, that was up to the District Inspector of Mines and my boss, the Elec Engineer in Charge.

But, several new rules came out of the accident from the Engineer approved by the Inspector.

That accident still makes me cringe, had it been on the 11Kv side, the laddie would have gone out the pit in a body bag. His megger was still there where he'd dropped it, both crocodile clips melted, plenty of molten metal burns around where he'd tried to clip on to a live leg.

I was a "stickler" for safety, I never saw this accident coming, but as my boss said, "it's never going to happen again" and I did my best to instill it in the men who I was in charge of.

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HV ocb's don't like cleaning fluid either, to this day I say this couldn't have happened to me, as I'd a few more years experience. One Christmas shutdown, one of the surface 11Kv CB's was set for an annual examination, which included an oil change, sadly, somewhere along the line, a 55gallon transformer oil drum had been had been used to store a water based cleaning fluid in and stored with other drums in the oil store. From the reports, when they took it out of the stores to use it, both the shift elec engineer and the elec had doubts about it. Have doubts DON'T USE IT!! No1 rule!! Changed the oil, finished the exam, time to push the truck back in, engineer was below the platform where the breakers were installed and was helping to line the pins up by sight. It never made contact fully before the "oil" vaporised, covering the elec engineer on super heated fluid, the elec was seriously injured too.

The force of the explosion blew the large roller door out, all the windows blew out.

The elc engineer died of severe burning to 90% of his body, on his way by helicopter to the burns unit.

Outcome was, ALL oils had to be marked by a colour code, ie hydraulic, transformer, gear etc with a different colour. All barrels containing transformer oil were tagged with a test sheet, tested and signed by the Elec Eng in charge.

We heard the colour scheme for oils was adopted world wide, result of that tragic accident, so now there is a universal colour code for all oil drums.

 

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We stopped using SF6 (Sulphur hexafluoride), it's not environmentally friendly to say the least.

 

I spent 19 hours down a Gypsum mine trying to locate a HV fault. Turns out mine map was missing a whole tunnel section, wooho did that set the cat among the pigeons with mine inspectorate.

 

Rule No 1, never ever use oil in an OCB that is not from a clearly labelled and SEALED drum. Not sure if they were a universal colour, our drums were mid blue  

 

Winding an OCB up to live contacts is not something I would ever authorise.

 

It's sad that accidents like this happen but I'd guess that majority were human error, not following the correct procedure and the permit to work. Yes it's a pain the proverbial to do so, but they are carefully thought out and there for very good reasons.

 

Every engineer I know has a tranche of horror stories. Some cock-ups are laughable but some get people killed.

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Flippin Heck Ayeup and you would sooner stay with Leccy.

 

I only know of man killed working with gas and that was his own fault.

 

Back in the early 60s I was on Ruddington Lane opposite Landmere Lane, the heavy gang was in the process of installing a new 12" main into Ruddington.

 

We were purging a length of recently installed main ready to go live, a new guy was in the grip watching the gauges when he decided to light a fag. He had seen old hands do it but what he hadn't noticed was them get out the grip, walk upwind and light the fag, returning to the grip to smoke it.

 

A glowing fag end won't ignite gas but the white heat of a match will, result Kaboom, one of the gauges hit him under the chin and damn near took his head off. There was hell to pay but as an apprentice I was well out of it, I do know the inquest verdict was misadventure.

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