Cable thief burned

[dennis]

You can induce volts through many things without any current flowing through them.

[Broadland Wanderer]

And it was a 50/50 chance that he got 6.3kV to earth or 11kv between phases.

[Tim Watts]

On Thursday 21 February 2013 23:12 Andrew Gabriel wrote in uk.d-i-y:

My dad was in the burns unit back in the 60's with another LEB engineer. This man had taken an 11kV voltage reading at an isolatable test point in a substation (bare metal probes, HV meter).

He forgot to throw the test point isolator before grabbing both probes with both hands.

The theory was that the arc had flashed over his skin, hand to hand largely not going through him. Needless to say he was a bit fried...

[Onetap]

He is a reformed man and has a job with a local bus company. He's a conductor.

[polygonum]

Thought you were going to say he had joined the police...

.... there is a joke there if you look for it.

[dennis]

Only if its the poleish police.

[polygonum]

Only ordinary coppers.

[dennis]

If you are cutting through a multicore cable you would be unlikely to touch two cores. If its a single core cable you would be unlikely to touch another phase at the same time so 11kV is to earth is more likely.

[Broadland Wanderer]

Except 11kV is Phase to Phase. 6.3kV phase to earth

[docholliday93]

Some time ago I was doing an installation in Gibraltar (fibre optics, not e lectrical). Just before I arrived they'd had an accident in the dockyard. A jointer had prepared an 11kV cable for jointing - isolation, earthing, and he'd marked the point to cut with tape. He'd then gone away and left the cutting to hi s assistant, who proceeded to take his hacksaw and attack the *other* 11kv cable which was running parallel to the one with the marker on. He was very lucky and survived, with burns where the metal had been vaporised and ejec ted from the cut. I think he lost all the hair on his head. They never fou nd the hacksaw blade...

[whisky-dave]

No the volts were across him :-)

Which obviuosly caused a rasin of the currant.

[Onetap]

Lots. It was a phase he was going through, but now he'll be able to resist temptation.

[Man at B&Q]

In completely the wrong direction, unless you know the "accident" left him infertile.

MBQ

[polygonum]

And I thought we'd moved away from Red for Live!

(Perhaps he'd have appreciated becoming a smurf...)

[Tim Watts]

On Friday 22 February 2013 13:23 [e-mail] wrote in uk.d-i-y:

In a similar vein my dad was supervising a jointer connecting streetlamps. This was central London, Paddington IIRC.

Anyway, they were working to maps and they both knew there was an HV and an LV cable next to each other. They looked the same, being lead-paper. No bright red sheath to give it away.

Anyway, dad went to get a sandwich and the jointer should have stopped work and done the same, but for some reason decided to carry on and get another joint in.

Dad got back and the jointer said "I've just peeled the lead serving from the cable and my fingers are tingling on the paper..." Bearing in mind he is kneeling on a rubber mat too.

Everything dropped, maps examined. The next joint was after a driveway and the cables had crossed reversing positions.

HV off, HV jointer sent for...

[Andrew Gabriel]

The 11kV cables I've seen (single or multicore) all have an earthed shield. Often it's very thin (much thinner than SWA armour), and it can't be steel on single core cable (has to be non-magnetic), but it's just there to guarantee an earth fault if the cable is cut, to trip out the upstream earth leakage breakers. That will probably reduce the chance of a direct electrocution, but it's perfect fuel to form the arc-flash plasma, which is basically a bomb going off in your face.

If you're still holding the cut end when the recloser operates (or it's laying on you or on the ground near you), then you would likely be electrocuted. He may be lucky if the arc flash blow him clear of the cable end, or the fault current whipped the cable away from him.

[Broadland Wanderer]

Some valid comments.

I wasn't disagreeing with you, but being lazy and not making myself clear. Yes, it was probably the flashover that got him, but there was a 50/50 chan ce that it was 6.3kV to earth rather than '11kV' as so often reported in th e media.

Your comments also put me in mind of an instance where fairly long lengths of lv s/c cables had been laid in steel pipes installed by a builder. I can 't remember the full detail, but I think it was a supply from a transformer , probably 500 or 800kVA, into a factory. Hysteresis currents in the pipes melted the insulation on the cables, to catastrophic effect.

[ARW]

What with, Coulomb's law?

[dennis]

Oh well, I must learn to proof read.

[ARW]