Wiring trough installation

[solarken]

This might seem silly to ask, but how do you install the end covers on nema 1 wiring trough, with the screw flange and screws accessible from the outside (concave) or with the screws hidden inside (end flush with the trough material)?

 

[tom baker]

I put the heads out. I installed a lot of Hoffman NEMA 1 wireway. I used my own fasteners. truss head Phillips or Sq drive machine screws and keps nuts. A keps nut has a built in star washer, use your driver bit on the machine screw.
The nut and just a bit of the machine screw are on the inside in a corner where a wire is not likely to contact.