Metal DNO CutOuts

[bernardgreen]

never an absolute need to cut a live cable,

Depends on what is absolute. It was "absolutely" necessary to disconnect the supply to a building in danger of imminent collapse while not affecting supply to other buildings supplied by the same main distribution feeder from the substation. As I recall it the service cable was exposed and the cutter with a time delay fitted to it. People then left the area.

 

[JohnW2]

Depends on what is absolute. It was "absolutely" necessary to disconnect the supply to a building in danger of imminent collapse while not affecting supply to other buildings supplied by the same main distribution feeder from the substation.

That was my point about (even underlined) "absolute". In the final analysis, one could shut down the entire grid if necessary - so it is always a matter of 'convenience' that results in a decision to cut a live cable (and it would certainly be very 'inconvenient' to have to arrange off-grid supplies for, say, life-supporting loads).

Kind Regards, John

 

[securespark]

I watched a food production programme earlier where sandwiches were cut sonically.
Wonder if they could do that to cables?

 

[Screech20]

There are no procedures in the DSR’s to cut a live cable in one hit. All cores shall be cut individually.

 

[JohnW2]

There are no procedures in the DSR’s to cut a live cable in one hit. All cores shall be cut individually.

That's what I would have expected, as a general rule.

However, as I have hinted, I imagine that one exception might have to be that of an 'unknown' (unknown source and destination) cable which is 'probably live' which has been found in a hole in a road. One presumably cannot safely dissect out the individual cores, so probably has no choice but to assume that it is live but nevertheless chop it 'in one hit' (whilst 'standing back' ) ... or is there some other possible approach in that situation? To 'de-power' an entire area would seem a bit excessive.

Kind Regards, John

 

[John D v2.0]

One presumably cannot safely dissect out the individual cores,

Why not? I'm pretty sure I could with some t&e if I had the right rubber gloves, the dno must do it every day.

 

[JohnW2]

Why not? I'm pretty sure I could with some t&e if I had the right rubber gloves, the dno must do it every day.

Maybe, but if it is an 'unknown' (large) cable, of unknown construction, in an unknown state of repair/disrepair, and quite possibly with metal 'coverings' (!) etc., I'm not so sure that I would want to be the person trying to do it, no matter how much PPE I had.

As you say, it would be very straightforward with T+E. Indeed, I have on plenty of occasions 'broken into' (not live) T+E in such a manner that nothing untoward would have happened if the cores had been live. However, even with something of the size/structure of T+E, if I thought that there was a risk that the insulation of the cores might crumble the moment I started disturbing them, I wouldn't dream of attempting it 'live' - and, of course, there is a big difference between a diddy bit of T+E and something of the size and rigidity of a drainpipe at the bottom of a hole in a road! Apart from anything else, with not the slightest hope of any 'slack', there would be no real hope of 'separating the cores' - even if they had been exposed, one would presumably have to try to cut through one core whist it was essentially in contact with others.

Kind Regards, John.

 

[Iggifer]

That’s why they have special tools, plastic bladed knives, wedges to press in between the cores, insulated hacksaws etc

They work live every day on all kinds of cable so they can usually identify what cable type, size and condition just by looking at it.

The only cables they don’t work live on are HV for obvious reasons.

 

[JohnW2]

That’s why they have special tools, plastic bladed knives, wedges to press in between the cores, insulated hacksaws etc ... They work live every day on all kinds of cable so they can usually identify what cable type, size and condition just by looking at it.

Fair enough - so when (if ever) do they use the 'spiking' kit (such as eric kindly illustrated recently)?

Kind Regards, John

 

[Iggifer]

HV. As they aren’t allowed to work on HV live they have to isolate the supply and lock it off (standard procedure ofc) but then they have to verify it’s dead by spiking the cable.

If all has gone to plan, nothing bad happens! If they’ve locked off the wrong circuit - there’s a rather significant bang and nobody gets hurt

 

[ban-all-sheds]

http://katalog.klauke.com/en/assg-battery-powered-safety-tool/

Cool.

Although I think I'd prefer to be more than 10m away from a 60kV bang, let alone a 110kV one.

 

[ban-all-sheds]

I watched a food production programme earlier where sandwiches were cut sonically.

Do cheese ones make a distinctive sound?

 

[mwatsonxx]

What a joke this place has become, its all the usual guessing and wildly ridiculous speculation. None of you have a clue about live cable working, the circumstances when its allowed and when its not allowed. The procedure of "spiking" is only reluctantly carried on unidentifiable cables, and the idea that it would be done inside a building is laughable.

And as to that hydraulic toy cable cutter, you would be better off using a chocolate pick axe.

 

[John D v2.0]

None of you have a clue about live cable working

I'm pretty sure I do. I quoted directly from my own experience of my own dno working live while I was in the same room as them.

 

[bernardgreen]

you would be better off using a chocolate pick axe.

Perfectly safe, provided the shaft of the axe is insulated..