overhead power lines

[airbrake2000]

hi there can anyone help does anybody know the legal height that overhead power cablesshould be above a navagiable waterway for 11000 volts. also is the height from the top of the tide or from when the tide is out any info would be greatly appreciated.

thanks

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[Benbow]

Charts show height above mean high water springs, ie the actual clearance is almost always greater than that shown.

Don't know if there is a legal limit - in the Menai straits the clearance of a set of power lines is only 22m.

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[floatything]

Four years ago I canoed down a local river to the sea. Lovely. Then I came to a bend in the river and as I turned I was lucky enough to notice a thin wire stretched across the river at a height of 30cm (1'). It was an electric fence - passing from one bank to the other - but fear not - skillful paddler as I am I managed to duck under it without shock. Finally get round the bend - looking back at the wire I just avoided and "WHAM"- - - - the buggers had led the wire back over the river just round the bend! great conducter is water you know :-(





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[snowleopard]

there are two across the tamar, 21m and 17m

bit of a b****** when your air draft is 19m.

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[Bergman]

About a month ago the exhaust dropped off my Toyota.

Whats that to do with power cables I hear you say, but wait.

I crawled about underneath to do a temporary "get you home" fix and every time I touched the body I got a shock.

Eventually did a string a wire job and got out from under and noticed I had stopped directly under some power lines 440kV I think. About half a mile further on these lines cross a navigable river. One wonders at the effect on a high mast when passing underneath.

Dunno how sensitivey stuff like GPS would get on either.

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[Benbow]

Going up Kyle Rhea in poor viz 1 day I was alarmed to see 2 intense radar returns stationary in the narrowest part of the channel. It finally dawned on me that they were directly below a set of power lines. There was nothing there as we passed so I assume it was some kind of RF generated by the cables that looked like a return to the radar.

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[William_H]

I doubt there is a legal minimum. Many years back I had a cat with about 10.5 metre mast height. Was motoring in upper reaches of Swan River and contacted 12kv power line. In fairness I had just passed under a bridge with about 3 metre clearance and pulled the mast up again as it was unstable dangling all over the stern. Yes the effect was alarming until it melted through the forstay and dropped the mast clear. Instruments were vaporised and much burnt wood between the forstay and the water line. not to mention blacking out the neighbourhood. Not recommended as a sport fortunately no one was hurt except pride shattered. NB for the man who saw the wires on radar. This was obviously a strong return of the upper side lobes. The beam is not exactly tight in angle and will transmit and receive to a diminishing degree above below and to either side of the intended main beam. A strong return will show up but not indicate that it is off the radar beam centre. Regards will

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[brianhumber]

No legal limit but safe heights are marked on Charts for MHWS. This is ok where shipping has traditionally used the waterway such as Tamar and Meini straits but a sod on other rivers.

My main gripe on this subject here in NW Europe is that YBW magazine articles and pilot books never include this info, such as the cables going to Pontrieux, up to Redon on the Villiane, etc.



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[cliff]

Seems there are not any but <A target="_blank" HREF=http://www.hse.gov.uk/pubns/ais8.pdf> here </A> makes interesting reading (OK it is about farmers but the principle is the same - ain't it?)

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