[SML] Electrical Wire thru Pulleys

[Stuart Wheaton]

On 9/15/2014 12:19 PM, mburris via Stagecraft wrote:
> Oh wise and powerful list:
>
> An upcoming production of Our Town needs a few electrified replica
> oil lanterns to fly in from the grid of a spot rigged house.  I have
> been asked repeatedly about the possibility of running the electrical
> wire thru a pulley while the same wire suspends the lantern gag.
>
> Am I overreacting by remaining staunchly opposed to this approach?
> Is there a cable suitable to the task?  The lanterns will be 12 volt
> pulling maybe up to ten watts.
>
> Loving the new server.
>


I think you have the ideal answer, but if the fixture was quite 
lightweight, and the blocks were insulated (think Harken type sailboat 
rigging) I'd be willing to accept it if there was no other solution.  I 
would prefer to use a separate lifting rope, and ideally the suspension 
cable would be fiber rather than metal.  Can you let the power cable 
swag? If not, I would consider putting the electrical on a separate 
plastic pulley so it doesn't tangle. I would be most concerned with a 
metal lifting cable that might pinch the power wire against the pulley. 
  If you used a jacketed wire like SO, on regular inspections you would 
be able to see potential damage before it got through to the conductors. 
  If the electrical cable does run through a pulley, make the pulley as 
big as possible to reduce the bending in the wire.

Stuart