Catenary guide

I cut a block of wood such that when placed in a low sided wagon, the top of the block is at the nominal height for the overhead catenary. The Sommerfeldt recommended height is 69mm above the rail.

I then made two lines across the top of the block to indicate the limits between which the catenary should be. The lines should be 6mm from center.

This technique made it fairly simple to determine the correct height and positioning of the masts.