I think you need to worry more about spark producing equipment (open brush type motors, ferrous metal blades contacting ferrous metal housings, etc.) than static electricity. Normally humidity has to be real low to produce static sparks. Your fan equipment should be rated spark proof and the motor should be fully enclosed (TEFC - Totally Enclosed Fan Cooled) at a minimum. As far as discharging the vent, vertically would be the best. Get it up where the breeze will dissipate it.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.