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So how do the DNO cut service cables whilst still being live? Always wondered, never had the opportunity to watch over ones shoulder! 
How do the DNO cut live service cables?
- Thread starter flyingsparks
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I'm referring more to cutting using a metal blade and not shorting cores together!?
Yes, it's an interesting question, and I haven't got a clue as to the answer - so look forward to learning. I suppose that it might be possible (these days, but not in days of old) to use a non-conductive (e.g. ceramic) blade, but one imagines that there would still be a pretty high chance of the cores shorting if one just chopped through all of them in one fell swoop.
Could it is perhaps be more of a 'delicate surgical procedure', carefully cutting each of the cores separately (rather than a 'brute force chop')?
Kind Regards, John
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I remember coming accross some internal DNO documents on the web which described the procedure in excruciating detail.
IIRC it was something along the lines of
remove the outer sheath down to the earthed metal layer, depending on the cable, apply a bridge cable to join together the earthed metal layer (not nessacery with "waveform" cable as the earthed metal layer can be cut loose and pulled away from the rest of the cable without breaking it). remove the earthed metal layer, cover any earthed metalwork with an insulating sleeve and then finally deal with the cores.
IIRC it was something along the lines of
remove the outer sheath down to the earthed metal layer, depending on the cable, apply a bridge cable to join together the earthed metal layer (not nessacery with "waveform" cable as the earthed metal layer can be cut loose and pulled away from the rest of the cable without breaking it). remove the earthed metal layer, cover any earthed metalwork with an insulating sleeve and then finally deal with the cores.
If that's the case (and if they then 'deal with the cores' one at a time) I suppose that corresponds pretty closely to the 'delicate surgical procedure' that I hypothesised. Where's westie?
Kind Regards, John
Well having watched a DNO engineer set-up his tools and then proceed to connect in a new three phase supply, I would agree with the sentiment of it having a similarity to a surgeon getting ready to perform an operation.
They dissect the cable. They won't cut through a cable live, through multiple cores/sheath at the same time!
Extremely carefully
I read somewhere in the dim past about a cutter that used an explosive charge to drive a ceramic cutting blade through live cable.
I read somewhere in the dim past about a cutter that used an explosive charge to drive a ceramic cutting blade through live cable.
Apart from the sterile field.
I could tell you but then I'd have to ....
Busy at the mo, I'll tell you tonight, but an eaelier poster had it about right
Busy at the mo, I'll tell you tonight, but an eaelier poster had it about right
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So I am, but I think we've probably got the general idea - careful dissection through the outer sheath etc., following be even more careful chopping (and making safe of ends) of the cores, one at a time.I'm waiting!
Kind Regards, John
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