OT: Big boys power cable jointing - or not?
N_Cook
Local power cut last week , the errant joint was laid by the trench so I had
to nose.
http://diverse.4mg.com/power_cable1.jpg
I laid a foot ruler laid over for scale. A few hundred houses affected but I
assume this cable only supplied a few dozen, then the linesmen isolated the
area transformer to fix the break , or do they work live? .
Two cable ends marked by "O" . Tar infill not obviously burnt, just what
seems to be an inadequate crimp had partly melted off the left hand end. I
somehow expected something like a phosphorous cauldron like they use for
welding railway line - not a crimp.
And certainly not an open crimp as showing the flute betwen the "o"s in this
closeup
http://diverse.4mg.com/power_cable2.jpg
Orange is probably clay pipe surround, along with lead sheet inside that and
then tar. Remaining cables showed no damage so no shorts.
The end of the cable is cut clean across the wire strands and no sign of any
brazing or the like. Wire strops and marine hawsers use a closed ring crimp
hydraulically compressed on. How much of a bang would such 1 inch diameter
cable failure make a couple of feet underground?
Michael Kennedy
"N_Cook" <div...@tcp.co.uk> wrote in message
news:igulrq$2rd$2...@news.eternal-september.org...
Wow thats completely different than what I have ever seen in the USA. I have
never encountered clay pipe or tar before.. Well aside from tar like
substance inside of the waterproofing housing for crimps..
Baron
About 20 years ago I was working on a factory site, when there was a
muffled pop and the lights went out, the factory grinding to a halt.
Out in the yard was a transformer and switch gear inside a brick
enclosure. No obvious signs of damage. The electricity board
engineers showed up and started to inspect the area.
Suddenly without any warning one of the engineers had one leg disappear
up to his knee through the tarmac. The surface had collapsed under his
weight into a cavity right where the cable had blown out. It took
several days to fix.
They put in a new transformer and feed cable. They used a hydraulic
crimping machine to make the joints in the cables, then potted the
whole lot in epoxy resin. I still have a new unused resin pack that I
was given from that repair. Must be well out of date by now... ;-)
--
Best Regards:
Baron.