Metal DNO CutOuts

[AdrianUK]

I know most if not all, DNOs don't like working on metal cutouts and prefer to do a 'dig & cut' externally to isolate before replacing.

Is this also true of the bigger, industrial, cutouts?

A full power down is planned at work. WPD are booked to isolate at 08:00 Sat & re-energise at 12:00 on Sun while the main switch & busbars are replaced. However, the cutout is a 400A three phase metalclad Lucy cutout.... I wondering if the DNO guy is just gonna turn up, take one look at it, whistle through his teeth & walk away.....

 

[Iggifer]

Was reading this the other day. Interesting read.

 

[John D v2.0]

I know most if not all, DNOs don't like working on metal cutouts and prefer to do a 'dig & cut' externally to isolate before replacing.

Not true, UKPN have loads of manuals on how to do it available online.

Also by way of further evidence, we had a metal 3 phase cutout full of pitch a couple of years ago and they happily pulled the (rewirable) fuses, chopped the PILC cable off (while live), and terminated it into a new plastic cutout in just about the same place.

 

[JohnW2]

.... they happily pulled the (rewirable) fuses, chopped the PILC cable off (while live), and ....

Do I take it that you mean that they chopped the cores of the cable, separately, rather than the whole cable at once?!

Kind Regards, John

 

[bernardgreen]

they chopped the cores of the cable, separately

The chopper could be a ceramic blade moving very fast that slices all the cores in a clean cut without distorting the cable. Being non conducting ceramic it will not create a short between cores

 

[John D v2.0]

Do I take it that you mean that they chopped the cores of the cable, separately, rather than the whole cable at once?!

Correct, maybe chopped is not the best word!
I didn't watch like a hawk, but never did they have more than one core exposed at a time, and when exposed they wore glorified marigolds.

 

[Simon35]

The chopper could be a ceramic blade moving very fast that slices all the cores in a clean cut without distorting the cable. Being non conducting ceramic it will not create a short between cores

https://www.amazon.co.uk/Slice-Precision-Ceramic-Friendly-Cutting/dp/B00UX6BQW2

??

 

[JohnW2]

The chopper could be a ceramic blade moving very fast that slices all the cores in a clean cut without distorting the cable. Being non conducting ceramic it will not create a short between cores

Are you sure - that sounds a bit iffy?

Kind Regards, John

 

[JohnW2]

Correct, maybe chopped is not the best word! I didn't watch like a hawk, but never did they have more than one core exposed at a time, and when exposed they wore glorified marigolds.

That sounds reasonable, and what I would have expected. I'm not at all sure about what bernard has suggested.

Kind Regards, John

 

[bernardgreen]

Are you sure - that sounds a bit iffy?

It is iffy but sometimes iffy is necessary

Slow cutters for "dead" cables are fairly common but they do short the cable and this can be a big bang if the cable is Live.

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

which cuts slowly and if the cable is Live allows for the explosion to happen without putting the operator at risk

http://news.demesne.ie/how-to-cut-live-electrical-cables-safely

 

[JohnW2]

It is iffy but sometimes iffy is necessary

It's fair enough in a hole in the road, with everyone 'standing back', but I was surprised at the suggestion that it would be done within a building.

Kind Regards, John

 

[bernardgreen]

I cannot recall the name of the company that make the "no bang" lable cutters for live cables, google can't find them. But it does find a lot of cable cutters for cables like barrage balloon anchor cables. https://forum.cartridgecollectors.org/t/british-cable-cutter-ctg/22562

The principle is similar but the "blade" is non conductive.

 

[JohnW2]

The principle is similar but the "blade" is non conductive.

Fair enough, but I presume that, no matter how fast the cut (with an non-conductive blade), there can be no guarantee that some contact between conductors will never result.

Kind Regards, John

 

[John D v2.0]

If you cut twin and earth or some other flat conductor you would be ok, to some high level of certainly.

 

[JohnW2]

If you cut twin and earth or some other flat conductor you would be ok, to some high level of certainly.

Yes, if one cut T+E in the right plane (with a non-conductive blade), you'd be unlucky to have a problem, but that would not require any 'fancy' kit - side-cutters with a non-metallic blade ought to do the job.

However, we're presumably not talking about 'flat' cable, so it's a totally different kettle of fish!

In the final analysis, there is presumably never an absolute need to cut a live cable, it being done for matters of 'convenience'. I suppose the most 'inconvenient' would be in relation to a cable of unknown source and destination found in a hole in the road, the certain isolation of which might require depriving quite a lot of consumers of an electricity supply for a while.

Kind Regards, John