Re: B2 Failure 09/04

[Simon Lister <listers@es.co.nz>]

You will also see traction crews around Wellington working on live overhead.  They have
special wooden ladders mounted on flanged wheels.  In this case the ladder provides
most of the insulation.  There is little or no risk to the staff provided of course you
don't put your spanner down on the metal gantry while holding the traction wire in the
other hand!

To this sort of work at the extreme, try watching linemen do live line work on the
220kV transmission line - they have special suits and tools.

Matthew Geier wrote:

> In article <3721601F.1662@REMOVEiprolink.co.nz>,
> David McLoughlin  <davemcl@REMOVEiprolink.co.nz> wrote:
> >Chris Sinnema wrote:
> >>
> >> The overhead is never de-energised when repair work is done. There is no need as
> >> the tramway workers are fully insulated, it is quite safe to touch the overhead,
> >> just dont try it though when it comes down, sparks fly everywhere.
> >
> >
> >I have watched on various occasions the tower-wagon crews working on the
> >trolleybus overhead in Wellington. Like Melbourne's tram overhead crews,
> >they also work on live wires.
>
> >touched both wires at once, they would cause a huge BOOM ??   But this
> >doesn't seem to happen. They work quite happily seemingly touching both
> >wires at once, and standing up right in the centre of the two wires at
> >times.
> >
> >Can anyone explain how they get away with it? It is a mystery to me, as
> >our ordinary electricity grid linesmen sometimes, sadly, get
> >electrocuted by touching ordinary power lines, yet the trolleybus
> >linesmen seem to touch the trolleybus wires with impunity.
>
>  A matter of voltage mainly. 600V DC is relatively easy to stop. Having
> decent footware, a good set of overalls and gloves would be enough.
>
>  You often find local supply authority workers making connections live
> on the 240/415 distribution system as well. (Taking great care...:-)
>
>  If those trolley bus guys grabed a wire in each BARE hand, I dare
> say they would not get the opportunity to try it again.
>
>  Tramway guys get it a little easier, they only have one wire up there.
> (As long as they don't grab the 'earth' side of a cross stay with one
> hand and the 'live' side with the other.).
>
>  I think you will find in both cases they pay particular attention to
> the insulating qualities of their footware.
>
>