OT orientation with JTM45 chassis ?

[jaysg]

I'm putting parts down on a weber JTM45 chassis. The OT is oriented so that the primary and secondary wires go through grommets facing forward and rear (perpendicular to the controls). I can't find a reference for whether the primary wires through the rear side grommet, or secondary wires through the rear side grommet. I imagine it's better one way than the other, but I can't logic it out -- longer wire runs for high voltage vs. high current.