One day in the mid '60s a mobile microwave link was being set up on top of a remote hill. The gang, as always, went out in plenty of time and having had no difficulty in proving the link took the mast back down and went to the pub in the van. After lunch they went back to the site and found a very heavy mist had come down, anyway they parked the vehicle and the apprentice amongst them elevated the mast by standing alongside the van and operating a lever that controlled the hydraulic mast. The mast went up and came into contact with a High Voltage overhead line hidden in the mist. The apprentice was killed instantly.
The van had been parked in a slightly different spot than before their lunch.
On Sun, 04 Jun 2006 16:50:22 +0100 someone who may be Derek ^ wrote this:-
How slightly different was slightly different? A few metres?
Did they not spot the line before going to the pub?
Did they not hear the electricity leaking across the insulators in the mist? This tends to be rather noisy, especially in remote areas with few other noises?
Transmission lines go over some ridges and along others, they tend to go round hills.
If the procedure is the same where you are as in Dorset, getting permission is simply a matter of filling in a couple of sheets of paper from the local council and waiting for a couple of weeks.
As others have said, switching off the supply seems like over-kill. I recently had some builders on the roof, within 10-15 feet of a similar overhead supply and the electricity board came out and put bright yellow plastic sheathing on the cable.
That, plus removing the overhead to my house and connecting up the replacement underground supply (which I'd installed) cost me ~ £2,000 but that included the cost of the armoured cable and a generator for the day (so my neighbour could continue work)
On Sun, 04 Jun 2006 19:48:01 GMT someone who may be John Anderton wrote this:-
People at work need to take reasonable precautions for their own and other people's safety. The tree people are presumably not trained in electrical safety, so sleeving the lines is a sensible precaution. As well as touching the lines directly they may make contact with a tool or ladder.
Is the tree close enough to the line that the possibility of a branch striking the line and bringing it down on somebody below is worth guarding against? If so then that would be a reason for isolating the line, as per the original posting. Disconnecting the conductors would only be necessary if they would be struck.
Those trained in electrical safety could approach such a line much more closely while it is energised and even work on it live. Indeed it is possible to work on 400,000V lines live, if one knows what one is doing and has taken the appropriate precautions. However, this is not something for tree surgeons.
Note for the stupid - don't try this yourself. Being electrocuted is not a pleasant way to die and it usually takes longer then people think. At the low voltages of house type wiring it is not a matter of dying instantly in a shower of sparks as in films.
Who knows? In the fog they could even have turned into the wrong field.
Maybe not, or they forgot about it. Or see above.
May not have been that high KV.
Except an OB vehicle with its engine running not to mention a generator.
Well then. Hill? Ridge?
They sure learnt their geography lesson the hard way.
My original post contains a clue as to why their perception of risk might not have been as sharp as one might have expected.
After leaving the Corporation I ran a private TV Studio with it's own OB vehicle. After a short while I made it a rule never to rig in the morning and then go to a pub for lunch, for a recording in the afternoon, which would have been appropriate for the geographical area we covered. IME something always went wrong, not nec. related to the pub lunch, could be a bad videotape or a power cut, but whatever something always seemed to go wrong.
Could be I'd been sensitised to it.
However by way of satisfying myself I made a posting on uk.tech.broadcast to see if anybody could recall the incident. I left the BBC in 1972 after 3 years with them and the incident was historic even then, though most older engineers could recall the persons involved on first name terms.
It turns out nobody so far has any recollection of this incident, but surprisingly similar (some actually practically identical) accidents with radio masts have continued to happen with depressing frequency, including one on the railway.
Others involved guying the mast to the Land-Rover, then driving away in it. Or driving up the M6 with the mast extended and bringing down the power lines across the Motorway on a Bank Holiday Saturday. :-))
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