[Mike S]

IMHO you should use the snap bushings or other protective device wherever a wire, tube or hose passes through a piece of sheet metal. Anything that can vibrate, or move around and damage itself or the part it is penetrating.

For larger holes, use caterpillar grommet.

Rubber grommets can be used also.

Snap bushings are cheap, and you can get them in assortments from Stein Also, you can order them from ACS.

 

[az_gila]

And when the strip grommet is really critical and must stay in place, use the Mil Spec stuff with gripping metal teeth...

http://www.aircraftspruce.com/catalog/appages/grommetedging.php