It's not a silly question at all! Wiring trough end covers can be a little fiddly, and it's better to ask than to force something and potentially damage it.Here's a breakdown of how to install both types of end covers you described, along with tips

Understanding the Difference
Screw Flange Accessible from Outside (Concave)

The end cover has a flange that extends outward from the trough. The screw holes are located on this flange, making them easily accessible with a screwdriver from the outside of the trough. The cover will have a slight recess or "bowl" shape.

Screws Hidden Inside (End Flush)

The end cover sits flush with the end of the trough. The screw holes are located inside the trough itself. The cover fits inside the trough.

General Steps for Both Types1. Preparation is Key



Turn off the power

Ensure all power is disconnected to the wiring within the trough. This is absolutely critical for safety.

Clean the Trough End

Wipe down the end of the trough where the end cover will be installed. Remove any dirt, debris, or sharp edges that might interfere with a tight fit.

Check the Hardware

Make sure you have the correct screws for the end cover. Typically, these are self-tapping screws designed to thread into the metal of the trough. If it's a cover you've used before, and you want to take it off and install it again, it's recommended that you replace the screws.

Inspect the Cover

Check the end cover for any damage, dents, or warping that could prevent a proper seal.

Installing Concave End Covers (Screws Accessible from Outside)1. Position the Cover

Align the end cover with the end of the trough. The concave side of the cover should face outward.2.

Align Screw Holes

Make sure the screw holes in the cover flange line up with the pre-drilled (or marked) holes on the trough.3.

Start with One Screw (Lightly)

Insert one screw into a corner hole and tighten it just enough to hold the cover in place. Don't overtighten yet.4.

Align and Insert the Remaining Screws

Insert the remaining screws into their holes.5.

Tighten in a Star Pattern (or Cross Pattern)

Tighten the screws gradually in a star pattern (or a cross pattern) to ensure even pressure and a secure seal. This helps prevent warping or gaps. Don't overtighten. The goal is a snug fit, not stripping the screws.6.

Final Check

Once all screws are tightened, visually inspect the perimeter of the cover to ensure it's sitting flush and there are no obvious gaps.

Installing Flush End Covers (Screws Hidden Inside)1. Position the Cover

Place the end cover inside the trough.2.

Align Screw Holes

Line up the screw holes on the inside of the cover with the pre-drilled or marked holes on the inside of the trough walls. This can sometimes require a bit of maneuvering.3.

Start with One Screw (Lightly)

Insert one screw into a corner hole from the outside of the trough and through the cover and into the trough wall. Tighten it just enough to hold the cover in place. Again, don't overtighten yet.4.

Align and Insert the Remaining Screws

Insert the remaining screws into their respective holes.5.

Tighten in a Star Pattern (or Cross Pattern)

Tighten the screws gradually in a star pattern to ensure even pressure and a secure fit.6.

Final Check

Check that the cover sits flush with the edge of the trough. There should be no gaps.

Important Tips for Both Types



Pilot Holes (If Necessary)

If the trough doesn't have pre-drilled holes, you might need to drill pilot holes. Use a drill bit slightly smaller than the diameter of the screws. This makes screwing much easier and prevents damage to the trough.

Screwdriver/Drill

Use a screwdriver or drill with the correct bit size to avoid stripping the screw heads. A cordless drill with adjustable torque is helpful to prevent overtightening.

Torque

Don't overtighten the screws. Overtightening can strip the screw heads, damage the trough, or warp the end cover. Tighten until snug.

Gasket (If Applicable)

Some end covers have a gasket to provide a watertight seal. Ensure the gasket is clean and properly seated before installing the cover. Replace if damaged.

Grounding

If required, ensure proper grounding continuity is maintained after installing the end cover. This might involve using a grounding screw and wire.

Troubleshooting Screws Won't Go In



Misalignment

Make sure the screw holes are properly aligned.

Pilot Holes

If no pilot holes, drill them.

Stripped Threads

If the threads are stripped, try a slightly larger screw or tap the hole to create new threads.

Cover Won't Sit Flush



Debris

Check for debris between the cover and the trough.

Warping

The cover or trough might be warped. Try gently bending it back into shape. A small gap can sometimes be sealed with silicone caulk.*

Gasket Issues: If there's a gasket, make sure it's properly seated and not damaged.By following these steps and tips, you should be able to install your wiring trough end covers correctly and securely. Remember to always prioritize safety by disconnecting power before working on electrical components. Flag for review